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tcj_27 1986-11

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1. A Tutor Program for Forth Writing a Forth Tutor in Forth by Bill Kibler Over the past few months I have been working on tutor programs and produced one for a computer class using BASIC The program just presented menus and then checked for keyboard input Next it jumped to a given line and ran the code The code in this case was text statements and took forever to en ter As far as program statements I used both X GOTO and IF THEN statements My overall feelings about the program was that it involved too much work for too little output Needing to do another tutor program and also wanting to do something in Forth I decided to try a tutor program using F83 F83 is the most current version of the FORTH 83 standard and is available both commercially and in public domain F83 has several extra features and is quite an improvement over previous versions of Forth People who have used other ver sions of Forth find F83 to be a real challenge to learn same words new meanings People who have not used Forth previously are usually lost im mediately after the prompt I figured I needed a tutor and help program that would be available after the prompt Af ter I started writing the program I was amazed at how easy and how fast I was able to write the mechanics of the program I spent about two days thinking about how I wanted information moved and displayed and then about on
2. 487 Cedarville 96104 112213 3 ALL Commercial rights reserved 113113 113113 Y OCC 3 IEEE IE TP ST TTT Cee ere Tee CIO EIE IE AE EXE EIE IGI EE GN SCR 1 TUTOR BLK LOAD BLOCK AND START OF TUTOR PROGRAM bdk 120186 variables and display routines VARIABLE ETUTOR END DISPLAYING TUTOR SCREENS VARIABLE STUTOR BEGINING SCREEN OF CURRENT GROUP VARIABLE NTUTOR NEXT TUTOR SCREEN OF GROUP gt L K OUP 36 IF 1 ETUTOR THEN CHECK FOR DISPLAY DISPLAY SCREEN OF TEXT 1 ENOUGH L SCR 1 DO 5 SPACES DUP BLOCK C L C L TUCK PAD SWAP CMOVE PAD SWAP gt TYPE WITHOUT THE TYPE 0 200 DUP L K EMIT 1 LOOP DROP TYPE WITH L K CR KEY LEAVE LOOP SCR 2 TUTOR BLK go get screens of information gotutor tutor bdk 120186 WTPRT 20 SPACES USE SPACE BAR FOR NEXT SCREEN ESCCHK DUP 27 IF 1 ETUTOR 52 THEN SET ESC FLAG WAIT WIPRT 13 EMIT PRINT THEN CR WITHOUT LF BEGIN KEY ESCCHK 32 UNTIL LOOP TIL SPACE KEY GOTUTOR DISPLAYS SCREEN ON STACK THEN WAITS DUP SCR 15 SPACES SCR CR
3. which means the disk TYPE TABLE As if all the different possible parameter values weren t enough to deal with we now have to deal with the physical characteristics of the disk drive and a few small details about how the alien format designer reads and writes his disks In the default type table make note of the byte containing the value 0E6H The value E6 describes the physical Kaypro disk format Each bit in the disk type table has a meaning as depicted in the listing s chart Bit seven defines whether the disk is single or double density Bit six defines the number of sides the disk has which also defines the number of heads the drive will have The Computer Journal Issue 27 Bit five defines how the sector numbers are organized Some formats consider both sides of the disk as a single surface Sector numbers are numbered with the first sector on side one of the disk continuing on the other side Other formats consider each side of the disk as different with sector numbers defined as side one sector one side two sector one Bit four defines the track count which refers to the way the disk is read In some formats the disks are read down one side of the disk and back up the other side The alternative is to read the disk down one side return switch side and read down the disk again The bit structure this far contains some obvious and some not so obvious information That information
4. Engineering Professional Software EN mation on what you are doing and share your developments with others Feedback Control The article on Feedback Control Systems by BV Engineering is a good example of both engineering software and a very important subject for any type of control system Feedback control can be applied o numeric machining robotics tem perature control and even magazine publishing To keep TCJ steering down the right path we need to know what the readers want and how we are deviating from the path We have renamed the the readers letter column FEEDBACK to better describe its purpose which is for the readers to ask questions respond with answers talk about what s hap pening in the computer field and most importantly where TCJ should be going Take time to write or to post a message onour BBS Computer Parts In the previous issue I mentioned that the power supply burned out in one of our Morrow S 100 systems I was concerned about finding a replacement since Morrow is out of business but I located Silicon Valley Surplus 4401 Oakport St Oakland CA 94601 phone 415 261 4662 who obtained much of Morrow s parts inventory A replacement supply was only 25 and in addition I bought a spare DJDMA disk controller board complete with the latest ROM for only 45 The people I talked to there were very pleasant helpful and knowledgeable 2200 Business Way Suite 207 Rive
5. voc eerrwo Loa PR Tau TE 18127 1600 7 SAnP 96 1 BLADE INTURRUPTER 8 TO GET PULSE EVERY 06 iNCH Of TRAVEL 1 Ahon FOUR BOLTS HOLD 12 GEAR TO 4 IN TIRE WICH TURNS f FREE ON AXLE 9 all fe a cops of 15 dey trial esreement Tex amp friesht extre Sead check or edd 1 20 fer COD Price me Price mey differ Whil supplies last Mo POs terms er credit cards 12 Sincon Vaney Surpius 415 261 4506 CLOSED 4401 OAKPORT OAKLAND Ca 94601 2 7 EQUIPMENT CASE SIMULATED LEATHER FINISH 10 INCH BY 12 INCH BY 4 INCH RUGGED ABS PLASTIC WITH CHROME PLATED LATCHES USE IT FOR A CAMERA CASE TOOL OR PORTABLE EQUIPMENT CASE GREAT WAY TO CARRY THOSE BOOKS AND SOFTWARE TO AND FROM WORK 29 PRECISION X Y TABLE a TWO GLOBE DC GEARMOTORS DC GEARMOTER 14 VOLT TO 12 VOLT DC OPERATION 50 TO 1 GEAR REDUCTION A PAIR OF THESE WILL MOVE A 500 LB ROBOT 64K DRAMS 75 EACH 699 FOR A PKG OF 8 SOLD IN PKG OF 6 OR 9 ONLY NEW CHIPS TESTED BY US AND EACH ONE GUARANTIED TO WORK 83 EA IF YOU BUY OR LESS SALE THIS MONTH ONLY 6116 40 82C51 199 74LS393 60 6502 199 74LS245 50 FDC 765 299 4517 40 80C86 329 CALL OUR MODEM CATALOG 415 261 4513 411 fe a coms 17101 esreemeat D n EE A A Sup ia lest Ko Pus Terms or credit SucorVaney m iliconWalley urplus On Gem 415 261 4506 Hee 10813 413
6. AF SPC Space COUT and print it DISKPRAM COM lt H E L P gt CR LF LF Syntax CR LF AO DISKPRAM cr CR LF AO DISKPRAM d CR LF AO0 DISKPRAM 1 or CR LF DPB and SKEW table for defalt drive Tables for selected drive Displays thls message DEFS CR LF This program is designed to provide the user with DISKPRAM show in Listing 2 is a DEFB 001 public domain 001 which is designed to DEFB CR LF that is able to display the DPB and SKEW table of a provide us with the basic information we DEFB CP M B OEFB CR LF 2 2 system This information can be used as the will require What is needed is to run DEFB decimal DISKPRAM on the alien system and oe CR LF ae for a program such as ESET COM written for the make a record of the parameters listed DEFB CR LF system With ESET the AMPRO s E drive may be used The values returned by this tool may be DEFB read installed in the disk DPB The disk OEFB CR LF and write allen 5 diskette formats CR LF LF type byte information will generally be NRECS OEFS 2 known Those portions of the type byte NPRINT DEFS 1 data which are not known be deter pee mined by some experimentation with the LAST DEFS 2 available parameters The menu driven i public domain utility 5 may STACK EQU be used to temporarily redefine the E P disk parameters Th
7. you own Turbo Pascal you should own TurboPower Programmers Utilities that s ail there is lo it Bruce Webster BYTE Magazine TurboPower Utilities offers nine powerful pro grams Program Structure Analyzer Execulion Timer Execution Profiler Pretty Printer Command Repeater Pattern Replacer Difference Finder File Finder and Super Directory The TurboPower Utilities package includes three 0500 disks reference card and manual 95 with Source code 55 executable only ORDER DIRECT TODAY MC VISA Call Toll Free 7 days a week 800 538 8157 x830 US 800 672 3470 x830 CA a Limited Time Offer Buy two or more TurboPower products and save 15 a Satisfaction Guaranteed or your money back within 30 days For Brochures Dealer or other Information PO COD call or write 3109 Scotts Valley Dr 122 L o Scotts Valley CA 95066 X 408 438 8608 M F 9AM 5PM PST The above TurboPower products require Turbo Pascal 3 0 standard 8087 or BCD and PC DOS 2 X or 3 X and run on the IBM PC XT AT and compatibles The Art of Source Code Generation Disassembling Z 80 Software by Clark A Calkins C C Software Introduction What is source code generation all about Well I consider this as the process of creating usable program source code in some language that is equivalent to an initial executable program By usable I mean that the source code has been suf ficiently documented or commented such tha
8. 2 3 130000E 3 We are now ready to perform an assesment of the stability of the loop with respect to changing gains and have a choice of three levels of resolution in choosing gain steps The LOCIPRO program can be directed to choose low or high resolution steps with the gain steps automatically selected by the program The user can also specify the number of steps manually For this example LOCIPRO was directed to compute a root locus for 70 gain steps for the stable platform problem The gain K was 15 specified to vary between 500 and 4000 The results are shown plotted in thes plane of figure 5 Jncompensated Root Locus E x gt c c Figure 5 Root Locus for Uncompensated Stable Platform A number of different things can be seen from the data presented in figure 5 It is immediately obvious that the system is unstable for all values of gain in the range of 500 to 4000 There are two poles in the right half plane for all values of gain These right half plane poles start at about 27 300i for a gain of 500 and migrate to 200 600i for a gain of 4000 There is also a pole which starts at 400 0i at a gain of 500 and migrates to 750 0i at a gain of 4000 Since this third pole lies entirely in the left half plane it does not worry us as far as stability is concerned This system might be stable for loop gains below 500 but we would lose the benefit of accuracy at lower loop
9. 45 And more are in the works The Computer Journal Issue 27 x1 p BD Software Inc maker of the original CP M 80 C Language Development System knows Time i precious So the compilation linkage and execution speeds of 805 are the fastest available even especially on floppy based systems Just ask any user With 15 000 packages 5010 since 1979 there are ots of users New Ed Ream s RED text editor has been integrated into the package making 805 truly complete self contained C development System Powerful original features CDB symbolic source level debugger fully customizable library and run time package for convenient ROM ing of code XMODEM compatible telecommunications package and other sample applications National C User s Group provides direct access to the wealth of public domain software written BDS including text editors and formatters BBS s assemblers C compliers games 816 much more Complete package price 150 All soft sectored disk formats plus Apple CP M available off the shelf Shipping free by UPS within USA for prepaid orders Canada 5 Other 25 VISA MC COD rush orders accepted DSofiware linc BD Software Inc 0 Box 2368 Cambridge 02238 617 576 3828 7 13 Feedback Control System Analysis Using Root Locus Analysis and Feedback Loop Compensation by Bert van den Berg B
10. FFFFh OFFFFh 32k 8000h 08000h JFFFh 32k 00008 48000h CALENDAR CLOCK 69 xix 53 0W WIT DA H Fite TE STAMPING Works with any Z 80 based computer Currently being used in Ampro Kaypro 2 45 10 Morrow Northstar Osborne Xerox Zorba and many other computers Piggybacks in Z80 socket Uses National MM58167 clock chip as featured in May 82 Byte Battery backup keeps time with CPU power off Optional software is available for file date stamping screen time displays etc Specify computer type when ordering Packages available Fully assembled and tested 99 Complete kit 69 Bare board and software 29 UPS ground shipping 3 MASTERCARD VISA PERSONAL CHECKS MONEY ORDERS C O D s ACCEPTED N Y STATE RESIDENTS ADD 8 SALES TAX KENMORE COMPUTER TECHNOLOGIES P O Box 635 Kenmore New York 14217 716 577 0617 The Computer Journal 18846 27 In Listing 2 you will see a portion of the BIOS that I am running on a 64180 equipped machine It shows a RAM disk driver and serves as a good example of some actual 64180 code that utilizes the memory past 64k The memory on my system a TRS 80 Model 4 with a XLR8er processor replacement board has a 64k block of memory starting at 0000h and then another 256k starting at 40000h You will notice a new instruction OUTO and it along with several other I O instructions with the 0 added are nothing more than the stan
11. Perhaps the only shortcoming of ZCPR3 is that itis not a complete replacement for CP M This is what the Z System does The Z System contains ZCPR3 and an additional module ZRDOS and is a complete replacement for CP M ZRDOS adds even more utility programs and has the nice feature of no need to warm boot C after changing a disk Hard disk users can take advantage of ZRDOS archive status file handling to make incremental backup fast and easy Because ZRDOS is written to take full advantage of the Z80 it executes faster than ordinary CP M and can improve your system s performance up to 10 INSTALLING ZCPR3 2 SYSTEM Echelon offers ZCPR3 Z System in many different torms For 44 you get the complete Source code to ZCPR3 and the installation files However this takes some experience with assembly language programming to get running as you must perform the installation yourself For users who are not qualifieo in assembly language programming Echeion offers our auto install products Z Com is our 100 complete Z System which even a monkey can install because it installs itself Z Com includes many interesting utility programs like UNERASE MENU VFILER and much more Echelon also offers bootable disks for some CP M computers which require absolutely no installation and are capable of reconfiguration to change ZCPR3 s memory requirements At present only Kaypro computers have this Option available BOOKS
12. graf term do pixel move draw int clip code if page wasn t the first U reset if page inreg h ah 5 select display page inreg h al page inc86 Ux10 inreg Gout reg Listing 2 Graphics Primitives SE SSS I I EE I ETT 4 end of graf term graph c graphics primitives for the IBM PC do pixel does a pixel Copyright C 1986 Donald Howes All Rights Reserved description turns the given pixel to the specified color provided that the copyright notice is included in all copies void do pixel x y color int x y color Note most of these functions use PC Video ROM BIOS calls to operate and are specific the IBM PC and close compatibles set the new color using intB6 X X X OX X This program may be copied for personal non commercial use only x FOR ICTR RRR III TTI TOTTORI KIO A TOIT RIOT IIT IIT II IIR I IOI TTI III IIT IA KIT KKK inreg h ah Uxc inreg h al color inreg X CX X inreg Xx dx int86 UxlU Sinreg 6outreg end of do pixel J include graph h graf init initializes the screen description sets the screen to 640x350 mode and initializes variables Also saves previous para
13. s fault the other was more serious and was my doing First for the easy one Art was kind enough to add information at the end of the column on how to contact me but the Z Node he listed there was not mine It was the Lillipute Z Node in Chicago which is the official ZSIG remote access system its phone number is 312 649 1730 Messages left for me there will get to me but I will get them sooner if they are left for me on my own node in Boston at 617 965 7259 I can also be reached on my voice phone at 617 965 3552 please don t mix the two numbers up especially if you are calling in the middle of the night Finding me at home is not always easy and your chances will be best if you call between 10 p m and just after 11 p m Boston time of course If you would rather write the address is Jay Sage 1435 Centre Street Newton Centre MA 02159 Now for the error I made In the discussion of the flow con trol package FCP and the transient IF COM I said that one can force use of the transient program by including a DU or DIR prefix or even just a colon in front of the IF This is not true I thought I had verified the statement experimentally but my experiment was flawed and the conclusion incorrect A colon does force the command processor to skip commands in the resident command package RCP and in the CPR itself and to proceed with a search for a COM file but all the FCP resident commands are intercepted no matter whether
14. 54 20 20 TLX 13709 USA SPAIN XENIOS INFORMATICA 593 0899 CONTACT AMPRO COMPUTERS INC TLX 50364 AUSTRALIA ASP TEL 415 969 0930 TELEX 4940302 pa rU T MAKER T Maker Co COMPUTERS INCORPORATED Ay 67 East Evetyn Ave Mountain View 94041 415 962 0230 TELEX 4940302 280 9 Zilog inc 9 Digital Research ZCPRI amp ZRDOS we of the enlightened New Wave of Eight Bit System Designs will tell it like it is and refer to this parameter as records per track Each RECORD we will determine to consist of 128 bytes of user data The DOS doesn t know anything bout sectors and tracks nor their size This is the realm of the BIOS where only those with at least a brown wizard s robe with gold stars might travel However the BIOS demands to speak in the terminology of sec tors and tracks so the DOS must fake it Knowing the number of standard RECORDS per track it can do some fancy math calculations and tell the BIOS what it needs to know to return a specific record from the disk s surface This is not as easy as one would suspect as records are laid down anywhere there is space seldom one after the other The Disk Parameter Block In actual application the parameters we have just discussed are returned to us in a fifteen byte data structure called the Disk Parameter Block which we will refer to as the DPB from here on The ad
15. We sometimes joke around the office that we are really in the business of publishing not selling software We have books Lots of books We have to have lots of books considering how powerful our software is and the large quantity of different packages we Offer Here are our best sellers ZCPR3 The Manual This is the bible for the ZCPR3 user An exhaustive technical reference bound softcover 350 pages Contains descriptions of each ZCPR3 utility program a detailed discussion about the innards of ZCPR3 and a full installation manual for those doing their own installation You could order it from B Dalton but why Get it from us ORDER FORM Payment to be made by Cash 885 N San Antonio Road Los Altos CA 94022 USA Check 415 948 3820 order line and tech support NAME ADDRESS TELEPHONE L REQUESTING LITERATURE 28 DISK FORMAT Money Order D UPSCOD D Mastercard Visa L Exp Date California residents add 7 sales tax Add 4 00 shipping handling Z sets you free The Z System User s Guide For those who are not technically inclined This is an excellent tutorial style manual filled with examples of how to use the power of ZCPR3 Z System most effectively written by two highly experienced Z users One user is a lawyer the other a writer this proves that anyone can use Z and benefit from it ZCPR3 The Libraries The extensive documentation for the libraries of ZCPR3 SYSLIB Z3
16. Wilson devised this nifty scheme for automatically loading the named directory register NDR with the names associated with user areas on a floppy diskette To give a user area a name one simply puts a usually zero length file in that user area with a name of the form When LDSK is run specifying the drive to be loaded it scans the disk for files of this type strips the leading hyphen and creates an entry in the NDR associating the name with that user number on the drive As I wrote in the last column I still have a lot of floppy only systems and I love LD SK Haven t you at times wished that you could take some program that only works on a single file and magically make it work with an ambiguous file reference Well Steve Cohen did so out of his programmer s hat he pulled the wildcard shell W to do it It just shows again that the only real limitation with the Z System is one s imagination Here are some examples of how W can be used Bob Freed wrote a quick little program called PCPCK that checks a file for proper transmission over Telenet s PC Pursuit packet network certain character sequences cause problems The trouble is PCPCK only works on a single file and it is no fun to run it manually on every file one is about to send somewhere But along comes W and all I have to do is en ter W PCPCK and away we go Or suppose you are just lazy and hate typing exact names of files Just put a W
17. case not so we are buying our second wrapping machine from another com pany because the first company s sof tware people and support engineers were unorganized and too tight with their sof tware This unit used a G amp L controller but they couldn t program it properly so we went with a company that was open and using a multibus system running multiple CPUs The first company s poor manament structure cost them two wrapping machine at over 300 000 each So when people talk to me about how im portant support is I say very Trying to pull all this together and con clude this column is not an easy task Art s editorial last issue got me thinking of what type of products to use and how the industry has gone hardware crazy I pointed out how support is important and keeping in mind the basic functions you hope to achieve with your system I have many systems at home and work to play with but still find my old CP M systems running Wordstar to be the best Why because they are easy to use and simple to run I can learn all the insides without too much problem and do all my own work without spending a lifetime of study For me SIMPLE is still the best Things to keep in mind are your objec tives costs support and your skills level Programs that do ten times more than you need may do what you want so poorly that a simpler and cheaper product would be more appropriate which is why I like WordStar Har dware systems tha
18. example is a file I O routine that sets a flag based on the conten ts of register A The instruction that sets the flag is either an INC A or A Prior to calling the routine this instruc tion is modified to provide the desired function Since these dif fer by only a single bit 3C and 3D hex respectively a clever programmer could have code such as The Computer Journal Issue 27 COMPUTERS NCORPCRATEO AUTHORIZED DEALER BEARuc oes SAVE 10 on AMPRO ALL AMPRO PRODUCTS READY FOR IMMEDIATE SHIPMENT SOME EXAMPLES OP nga avaliable MODEL DESCRIPTION REG PRICE DISCOUNT PRICE 18 1 Little Board SBC 249 00 224 10 Lite Board PLUS SBC 289 00 260 10 Little Boara 186 SBC 495 00 445 50 Proto Board 179 00 161 10 Video RAM Emulator 195 00 175 50 STD Bus SCS Board 119 00 107 10 CPIM System wi2 Drives 995 00 895 50 PC DOS System w 2 Drives 1295 00 1165 50 Expandabie PC DOS System 1395 00 1255 50 Please ada 3 00 8 00 on systems for UPS shipping amp handling residents add appropriate sales tax Some reatnctions appty to credit and large quan tity orders for informabon Allow 2 3 weeks for 122A 222 or 321 systems CHECKS PO s CALL NOW CALL COLLECT 415 376 0125 BEAR ELECTRONICS P O Box 61 Moraga CA 94556 e Z Best Sellers 280 Turbo Modula 2 1 disk 69 95 The best high level language development system for your 280 compatible computer Created by Borland Inte
19. the disk size in bytes may be determined by DSM 1 doubled BSH 7 times The maximum number of directory entries the DIREC TORY NUMBER 1 contains the maximum number of direc tory entries plus one contained upon the concerned disk This is a word sized parameter and indicates that the DOS is able to support up to 256 directory entries This large number of direc tory entries is generally found oniy in hard disk systems The ALV or INITIAL ALLOCATION VECTOR is a word sized parameter which the DOS maintains for each active disk This word is a string of DSM 1 bits in length in which each bit refers to an allocation block If the bit is high a logical 1 then the block is in use Each byte in the initial ALV may be used to build a full sized allocation vector for the concerned disk with these bytes becoming the leader bytes for the vector Some number of the ALV bits will be set high to permanently reserve the directory area of the disk Next on the list is the CKS word which is the DIRECTORY CHECK SIZE parameter This word sized parameter is used by the DOS to see if the disk on the concerned drive has been changed by the user since the last warm boot If the disk is determined to have been changed it is assigned read only status and we are given the all too familiar error message when we try to write to it If the CKS word is a zero value this disk has been changed testing will not be done This is
20. 68010 68020 Primer by Kelly Bootle and Fowler The Waite Group Howard W Sams The 68000 Principles and Programming by Leo Scanlon Howard W Sams 68000 Assembly Language Techniques for Building Programs by Donald Krantz and James Stanley Addison Wesley Publishing Company 68000 Assembly Language Programming by Lance Leven thal Doug Hawkins Gerry Kane and William D Cramer Osborne McGraw Hill The 68000 Microprocessor Architecture Software and Inter facing Techniques by W Triebel and A Singh Prentice Hall 68000 Microprocessor Handbook by William Cramer AVM Systems Gerry Kane Osborne McGraw Hill 68000 User s Manual by J Carr Prentice Hall MC68020 32 bit Microprocessor User s Manual by Motorola Prentice Hall Basic Microprocessors and the 68000 by Ron Bishop amp the Motorola Semiconductor Group Hayden Books Dr Dobb s Toolbook of 68000 Programming Edited Prentice Hall Programming the 68000 by Rosenzweig and Harrison Hayden Books The Computer Journal issue 27 Programming the 68000 by Steve Williams Sybex Computer Books Self Guided Tour through the 68000 by M Andrews Prentice Hall 4 The above books can be ordered from Magrathea 8842 Southeast Stark Portland OR 97216 Phone 503 254 2005 68000 SINGLE BOARD COMPUTER 395 00 32 bit Features 8 bit Price Hardware features 8MHZ 68000 CPU 1770 Floppy Controller 2 Serial Ports 68681 General Purpose Timer Centronic
21. 80 system and in The Computer Journal Issue 27 cludes a clock oscillator watchdog timer Z8500 bus interface dynamic RAM interface that handles 64K and 256K memory chips and decodes the in struction set which permits code and data to be separated into different ad dress spaces and doubles memory space BD Software is now shipping revision 1 6 of their C compiler This revision in cludes the RED editor with source code which reacts interactively with the com piler for easy error corrections the buf fered I O functions have been changed so that they are now K amp R compatible programs written for V1 5 will have to be modified the compiler error detec tion and diagnosis have been improved plus there are numerous other im provements Note that the source code for all the library functions is included The BDS C compiler has been my first choice as a programming language for writing text filters and drivers for our phototypesetter and the new version is even better Another entry is Borland s 8 bit Turbo Modula 2 compiler which is being distributed by Echelon and Micromint and will be very important for people writing non trivial programs but who don t like C Turbo Modula 2 has a lot of the familiar syntax of Turbo Pascal plus separate compilation library facilities similar to C Interfacing to assembly routines has also been greatly improved compared to Turbo Pascal as Turbo Modula 2 has a CODE statem
22. 8k program would result in 5333 lines of Z 80 assembly code and when commented will take up 100k of disk space I don t recommend users try disassembling programs in excess of 16k unless they have a VAX to work with How can you tell if a program was originally written in assembly language and is this really important With some of today s optimizing compilers this question becomes less impor tant But in general when I first look at a disassembly of a program I want to see if there is a consistent flow of logic to the code When I see code that is composed of a seemingly endless series of calls to subroutines grouped at one end of the program either low or high addresses I know this came from a threaded type compiler and will be a bear to disassemble I like to see subroutine calls followed by code that uses the Z 80 flag register like CALL 1234 followed by JR NZ 4567 This is the way assembly programmers work but few compilers are smart enough to do this Most would have inserted a AND A or similar instruction Additionally compilers produce code that executes under all conceivable conditions Thus there will be many absolute jump instructions and few relative ones If you find that you cannot tell if the code was produced by a com piler or an assembler then it probably does not make much dif ference Over the years users have suggested various projects for disassembly These have ranged from fairly reasonable on
23. FCBI 1 JP Z HELP 2 JP Z HELP CALL CALL SKEW JP EXIT b HELP 10 HLPMSG CALL COSTR exit warm boot HL LD SP HL RET 10 A FCBI DEC A JP P OPB2 CALL FCN25 2 LD E A ADD 10 DRIVE A CALL FCN14 CALL FCN31 PUSH HL we we me we we we Fred Willink C Thomas Hi lton Converted code to HMAC format bell horz tab line feed carr iage return space stack pointer set up local stack save the ccp pointer for return SKEW help 2 point to help message display help recover ccp s stack ptr drive code given convert to 0 save for select make drive code printable save It for dump CALL POP LO CALL CALL CALL RET LD 10 10 DEC JP CALL LD LD CALL CALL CALL POP DE SPT 2 DE BSH DE BLM DE EXM CVTI DE DSM 2 DE ORM 2 DE ALVO DE DE CKS CVT2 DE OFF CVT2 HL DSPLAY COSTR HL B 15 HEXDMP COCRLF COCRLF A ACROSS A FCBI A 2 25 14 FCN31 E HL HL D HL DE HL NRECS HL A 24 BIOS HL DE HL DPHADR HL HEXADR HL DPH COSTR BC make dph values printable wee ee we ee we dph table print It alt print hexdump of dpb number of records to
24. GNO 14 15 GNO 16 17 GND 18 19 GND 20 21 GND 22 23 GNO 24 25 GND 26 27 GNO 28 29 GND 30 31 GNO 32 33 GNO 34 P4 CONNECTOR TERMINAL 1 GND 6 2 RXD 7 3 8 4 CTS 9 5 RTS 10 P4 CONNECTOR MODEM SE 1 GND 6 2 RXD 7 5 TXD 8 4 CTS 9 5 RTS 10 PR CONNECTOR PRINTER 1 STROBE 2 00 5 01 4 02 5 03 6 D4 7 05 8 06 9 07 10 BUSY MEMORY MAP 000000 07FFFF RAM 080000 O8FFFF 100000 OFFFF X2 180000 17FFFF PRT 200000 27FFFF SLK 280000 2FFFFF SIO 300000 37FFFF 380000 3FFFFF PROM ON BOARD INTERRUPT LEVELS NMI external al 0 not an interrupt at 1 external 2 Printer internal 3 Serial interna 4 Floppy disk Internal 5 external 6 external 7 Where Do We Go From It s very likely that the 68000 will replace the Z80 as the choice for hobby and experimental projects and the com bination of the TinyGiant and the K OS ONE operating system will provide a very good development platform The lack of software is a major problem with any new har dware or operating system developers won t write the programs until a lot of the systems are sold and people won t buy the systems until a lot of software exists at least that s true with a mass market appliance type computer But this is initially aimed a
25. Print Spooler Part 2 _Tegue Number 4 Optronics Part 1 Detecting nerating and Using Light in Elec tronics Multi User An Introduction the CP M User Function More ie Build Hardware Print Spooler Part 3 Beginner s Column Power Supply Nesign _ jue Number 5 Optronics Part 2 Practical Ap plications Multi Processor Systems True RMS Measurements Gemini 10X Modifications to Allow both Serial and Parallel Operation Issue Number 6 Bui esolution S 100 Graphics Parti System Integration Part 1 Selecting System Components Optronics Part 3 Fiber Optics ontrolling DC Motors Multi User Local Area Networks DC Motor Applications Ta ber 8 Build VIC 20 EPROM Programmer Multi User CP Net Build High Resolution S 100 Graphics Board Part 3 System Integration Part 3 CP M 3 0 inear Optimization with Micros issue Number 9 Threaded Interpretive Language Part Introduction and Elementary tines interfacing Tips amp Troubles DC to DC Converters Multi User C NET Reading PCDOS Diskettes with the yrrow Micro Decision DOS Wars Build a Code Photoreader issue Number 14 e Hardware Tric Controlling the Hayes Micromodem II from Assembly Language Part 1 e 5 1008 to 16 Bit RAM Conversion Time Frequency Domain Analysis BASE Part Two Interfacing Tips and Troubles Inter facing the Sinclair Computers Part 2
26. Software 1907 Alvarado Ave Dept M Walnut Creek CA 94596 415 939 8153 CP M is a registered trademark of Digital Research Inc TURBO Pascal is a trademark of Borland International sion number Echelon Responds On page 46 of TCJ issue 24 appears a letter from D D Item 4 of the letter states Z System is public domain but surely the BIOS from Micromint or Ampro is not public domain specifically which files is one allowed to copy for friends Our reply First Z System is NOT public domain period All aspects of ZC PR3 and ZRDOS that make up the Z System are copyrighted But ZCPR3 CP M CCP replacement is special Programs and utilities written by Richard Conn can be freely copied and given to friends but they can not be sold You need a license from Echelon to sell ZCPR3 programs Second ZRDOS the CP M BDOS replacement combined with ZCPR3 is Z System is licensed and supported by Echelon You need a license from Echelon to sell ZRDOS And it is against the law to copy is and give it to friends Subject files are ZRDINSnn COM and ZRDOSnn BIN where is the ver But support utilities associated with ZRDOS can be feeely given to friends who have obtained ZR DOS package from us These are AC VTYPE VIEW SFA DFA COMP DOSERR DOSVER DISKRST LOGGED DRO SRO and SRW Each was written to take advantage of features of Z System and thus only run if ZRDOS is present Z System is full
27. The MMSFORTH System Compare A totai software environment custom drivers for printer video and keyboard improve speed and flexibility New TRS 80 M 4 version too Common SYS format gives you a big 395K 195K single sided per disk plus boot track Common wordset 79 Standard pius MMSFORTH extensions on ali sup ported computers Common and powerful applications pro grams available most with MMSFORTH source code so you can use them com patibly with the same data disks across all supported computers Very fast compile speeds and advanced program development environment A fantastic full screen Forth Editor Auto Find or Replace any word for ward or back compare or Pairs Edit any two ranges of blocks much more Temporary dictionary areas QUANS VECTs vectored 1 and many more of the latest high performance Forth constructs Manuai and demo programs are bigger and better than ever Same thorough support Users Newslet ter User Groups worldwide telephone tips Full consulting services Personal Licensing One person on one computer is standard Corporate Site Licensing and Bulk Distribution Licens ing available to professional users A World of Difference The total software environment for PC XT TRS 80 Model 1 3 4 and close friends e Personai License required MMSFORTH V2 4 System Disk TRS 80 Model 1 requires lowercase DOEN 1 40 track drive ePersonal
28. choices are both included in a text file that is read in by the program This makes it very easy for the user to create and modify the display and the scripts Con sidering again our program development example we might create a menu screen with the following display S Select name of program E Edit program source code A Assemble program to HEX file L Load program to COM file R Run program F Full cycle edit assemble load These choices might be associated with the following command scripts S setfile 1 Enter name only of program to work on E edit n1 Z80 zas n L mload ni F edit n1 280 zas n1 if er mload 91 There are two interesting new parameters illustrated in these scripts One is the N1 parameter As part of the Z System environment buffer four system file names are defined MENU can read these four file names and put into scripts the complete filename Fn the name only Nn or the type only Tn where n is 1 2 3 or 4 The selection sets the first system file name using the program SETFILE and the others then use it The Computer Journal Issue 27 The S selection illustrates the other new script parameter prompted user input When the script for choice S is being expanded the text between quotes will be displayed as a prompt to the user and one line of user input will be substituted into the command line in place of the prompt It is with prompted input t
29. con stitute a command or data to be added to the file Then you will look at those subroutines that reference the keyboard either directly or via a status check subroutine One of these routines Will have to determine if the key is a command key In TURBO Pascal commands consist of a control character followed by another character By examining the data areas initially you have already found the location of the key translation table Then the subroutine you are looking for will contain a reference to this table When it is found it must be there you then discover that it also references another data area at the same time Isn t that interesting Looking at the code shows that as it scans the key translation table it keeps a count of which one matched if any Then when a match is found it doubles the count and adds it to the start of the second table Because you know that addresses in the Z 80 are two bytes long 16 bits you then determine that the second table is a table of subroutine ad dresses for all possible commands Now we are really getting somewhere Looking at the documentation determines what functions are performed for the different commands All of a sudden you have determined the address and function of many more subroutines Of course you quickly document and label these Every once in a while you may find yourself hopelessly lost within a particular subroutine At these times document it as The Computer Journa
30. display across screen save see f drive was specified test ffsno yes select drive no get current drive select drive get address of dph save dph address for records per track offset for seldsk hl dph desxlate table de dph dph in hl and save display dph address traller message for address display 188 ense JEYNdWOD RECLOP SHOWD POP LO JP LD CALL RET LD XOR LD LO CALL CALL LD DEC LO JP LO INC JP Lo CALL MORE ENTRY WHERE NOTDON LO 10 LO JP LO INC LD LO JP JP JP LO JP EX CALL 10 RET 10 CALL CALL LO JP DEC LO JP HL A E NZ REC3 HL NXLATE COSTR BC 0 A POSIT A 45 BIOS PRINT HL NRECS HL H 2 SHOWD NRECS HL RECLOP HL TBLMSG COSTR A 20 POSIT A HL OPHADR LAST HL ENTRY HL LAST HL LAST HL E HL 0 0 27 NC ZERF IL 1 2 WHERE 0 NZ NOPE A POSIT 20 NZ ZERFIL DE HL DECOUT A POSIT 0 2 COUT COSPAC POSIT 0 Z ZERFIL A POSIT A MORE 9 9 9e we we we we we we 9 we we we we we vs us ve ve vs vs Do ue Ve ye Ve ws De ve ve we 9 we we we we we we we we we get low byte or with high If zero no translate done no translate message Clear record number clear a initialize counter Offset to sectran hl xtate bc display r
31. display the next screen L will list current screen 8 L will list previous screen 1 EDIT will invoke the line editor with screen ready to edit O NEW will start editing at line O and and allow the text to be entered one line after the other HEX 100 80 DUMP will do a hex dump of memory location 100h to 180h DEBUG LIST will allow stepping through list when used next as in 1 LIST SCR 9 TUTOR BLK last intro screen with list of words bdk 120186 TUTOR WORDS CHPl introduction CHP2 fundamentals CHP3 RPN and STACK CHP4 editor commands conditionals nests CHP6 fixed point operations loops amp nested 8 number types CHP9 var const arrays 10 F83 structure CHP11 Input Output CHP12 extensions GLOS alphabetical glossary of F83 words GET next chapter REPT begin chapter again HELP repeat these screens START TUTOR start at CHPI SPACE BAR next screen ESC stops display PRTSCR GET and REPT pointers mation A typical problem is getting into and out of lessons Many times you can get out but must start all over with lesson one again A recent tutor program I must use makes you enter information at each prompt before you can continue on This is not acceptable as the only information I want is at the end of each lesson a review and glossary My Forth tutor program gives you many options from printing an index or the whole thing to LISTing a single screen A
32. is the 68000 that runs at 8 Mhz with no wait States There are two EPROMS a dynamic RAM controller four RAM chips and a 686819 dual serial chip There is also an unbuffered expansion bus provided The 68681 is almost a complete I O system on a single chip There are two serial ports and a timer on the 68681 There are also some extra input and output bits that can be used Each serial port has its own internal baud rate generator that can be 4 68000 TinyGiant set from 50 to 9600 baud The system startup assumes that the console terminal on the first port is set to 9600 baud The other port is assumed to be for a modem and is set to 1200 baud This port could be used to support a serial printer if a modem is not needed The timer is used as the basic system timer for a time of day clock When the PRN device is selected a parallel printer port made from a latched buffer is used The 1770 floppy controller can control up to four 5 or 3 inch floppy disk drives At the present time the software is only supplied on 5 inch floppy disks but it will also be supplied on 314 disks in the near future The 1770 controller has an internal clocked digital data separater so no adjustments are needed There is no DMA controller so all I O is done with interrupts The board is supplied with 128k of RAM but can be expanded to 512k by simply adding the memory chips The memory is con trolled with an MB1422 dynamic RAM controller which takes care
33. of all the timing and refresh for the 64k x 4 dynamic RAMS There are four RAM chips in the basic machine 12 more can be added on board and an expansion board can be added to provide additional memory There are two EPROMS that contain the boot code and a very simple hardware debug monitor and there is a lot of empty space in the PROMS that could later be used for code There are two expansion connectors that provide all the needed address data and control lines The 64 pin expansion bus connector has all the raw signals just as they are on the 68000 itself and it is an unbuffered bus which means that buffers have to be provided for the bus lines on the first expansion board The other expansion connector has some signals derived from logic on board There is a priority interrupt encoder that is The Computer Journal Issue 427 connected to autovector interrupts To use the TinyGiant you have to connect a power supply a terminal and a disk drive The board requires only 5 volts at about 2 amp and some at 12 volts for the RS 232 the 12 for the RS 232 is generated on board and the power connector is the same as a floppy drive The EPROM monitor is set up to boot the K OS ONE operating system from a floppy disk when the power is applied All of this should be in a proper case and any of the cases for the Ampro Little Board should work fine because the board is the same size The cases and power sup plies for the PC clones should
34. of assembly programming it is possible to write real obscure code Code can be self modifying self relocating or a combination of these and you will have fits trying to disassemble it as the code may not function as it first appears Self modifying Code There are many possibilities here I will touch on a few of the most common techniques I have run across Self modifying code is used to either save memory possibly increasing execution speed or to confuse the person trying to disassemble it One very common procedure is to aiter the contents of a data item being loaded into a register The instruction 1 0 may be changed into LD A 5 by writing a 5 into the second byte of the instruction By using this type of code the execution speed is improved an immediate load is about twice as fast as an indirect load and the code is a little smaller Some disassemblers point out these types of self modifying code MD does not If not these are easy to spot Just look for unresolved address references that are within the boundaries of the program code A more difficult type of self modifying code to locate is when the instruction itself is changed Some subroutines mainly I O have complement functions For example reading or writing to a file Because they are very similar programmers are tempted to re use the same subroutine for both functions Only a flag or register value indicates which function is to be performed An
35. presence of Plu Perfect Software s exciting Backgrounder task swapping The new FCP COMIF combination also adds an important new twist in transient processing They have the option of loading the transient code not at 100H as has been done until now but high in memory where it will not overwrite a user program that is loaded at 100H In this way the GO command can be used to rerun the last user program after flow control processing no matter whether resident or transient flow processing was used Thus the user need not concern himself with how the flow processing was performed While I was at it I also added two new commands to the FCP module One IFQ if query is designed to help users advanced as well as novice learn how flow control works or 29 perhaps is not working as one intends It displays on the screen the complete flow state of the system the true false status of all IF levels The second is ZIF zero ifs It is like XIF end all ifs except for one thing XIF clears all IF states only if the current IF state is true if the current IF state is false XIF is flushed ignored just like any other command ZIF on the other hand clears all IF states no matter what I m sure that everyone who has experimented with flow control has at one time or another gotten himself so messed up that nothing seemed to work The only way out short of rebooting was to type a string of FIs until things started working again Z
36. sequence of commands manually but rather because it allows other programs to do so automatically The simple stan dalone alias created with the original ALIAS COM or one of the more sophisticated alias programs like TALIAS BALIAS or VALIAS is a good example Let s see how such an alias might be used Suppose we are working on a new program with a source file called MYPROG Z80 Our standard sequence of operations is to edit the source with command like EDIT MYPROG Z80 and then to assemble it with a command like ASM 2 and then to load it with a command like MLOAD We can speed things up and reduce the amount of typing and the number of typos by creating an alias which we might give the name DO COM We would create it with VALIAS for example with the following script com mand line form EDIT MYPROG Z80 ASM MYPROG AAZ MLOAD MYPROG Now when we want to start a new cycle we just enter the easily spelled command DO The rest is automatic But how does this alias actually work When you enter the command the operating system loads DO COM into memory and starts running it DO contains within its file the script line put there by VALIAS COM for example when the alias was created DO COM has code to determine where the Z System multiple command line is located in memory this in formation comes from what is called the environment descrip tor whose address is instal
37. stage power amplifier the torque motor platform inertia rate sensor etc The Computer Journal issue 27 13E 5 52 444 35 1 Rate Gyro Figure 4 Loop Block Diagram The transfer functions describing the loop elements of Figure 4 are entered into the LOCIPRO program and the program is used to compute the root locus as a function of gain The value of the gain K block 1 of figure 4 is allowed to vary between the limits of 500 and 4000 After data for the last transfer function block has been en tered into LOCIPRO the program lists all the data and requests whether there is any need to edit the data Once editing if any has been completed LOCIPRO will list the composite open loop transfer function The closed loop transfer functions may be saved to data files for future use by LOCIPRO or the Signal Processing Program SPP After the root locus has been com puted the pole zero vs gain data may be vectored to the display the printer or to an ASCII data file The ASCII data files may be plotted using PDP PCPLOT PLOTPRO or other plotting routines The composite open loop transfer function for the system described by figure 4 is computed by LOCIPRO and is listed here Open Loop Transfer Function Data Numerator Coefficients Ascending Powers of S Exponent of Coefficients 5 0 100000 1 Denominator Coefficients Ascending Powers of 5 Exponent of Coefficients 5 0 000000 0 1 100000 1 2 440000
38. t stop Well we all hope we will get the program right eventually so we really would like to be able to get out of the alias Flow control can help us again Consider the script EDIT 1 280 AL 1 ECHO EDIT AGAIN IF INPUT DO 1 FI Now before reinvoking DO the alias asks us if we want to edit the file again If we give a negative answer anything other than carriage return space bar Y for yes or T for true the loop is broken If we answer affirmatively with a quick tap of the return key we start again Very quick and easy There is one subtle problem however If you go through the exercise of expanding the alias scripts you will see that with each cycle an extra FI builds up at the end of the command line Even more careful analysis will show that with each cycle we go one IF level deeper as well One of two problems will eventually spoil our plan Either the command line will get so long that it won t fit in the command line buffer or we will run out of IF levels eight is the maximum What can we do about these problems The FCP has the XIF command precisely for this reason If we put an XIF command at the beginning of the script we will reset the IF system to level 0 every time we reenter the loop Then the limit will be overflow of the command line When this happened to me I invented a special type of alias the recur sive alias and incorporated it into my VALIAS program as far as I know only VALIAS and A
39. the same criteria as corporations or government agencies when it comes to buying computers When a government agency buys a computer the taxpayer pays the bill When a corporation buys a computer the company s stockholders pay for it Individuals however have no choice but to spend their own money So the price of the machine as well as its features clock rate ease of use bundled software etc become deciding factors in a sale George goes on to say Thus the key to next year seems to be in the hands of individuals just as it was in 1986 Will they continue to buy at the pace they established in 19862 Digesting what George said I feel that when corporations and government agencies became the primary buyers most sellers structured their product line marketing organization and pricing for this big business segment Now that individuals and small companies are again the primary buyers these sellers have too much built in overhead cost and are burdened with products and marketing plans designed for those spending someone else s money The ones succeeding in the current market are the lean and hungry ones who can provide the features and prices deman ded by the individuals spending their own money give you the answer The darndest thing I ever did see if you re at all interested in what s going on in your system it s worth it Jerry Pournelle BYTE Sept 83 areas Ever Wo
40. there is a colon or not There is a very good reason for this The FCP commands must be executed even when the current IF state is false This is especially clear for commands like ELSE which reverses the current IF state and FI which terminates the current IF state Transients ELSE COM and FI COM could not do this After a bit of thought you can probably see that this is true for all the flow control commands I have long been searching for ways to give the user control over whether IF processing is performed by resident or tran sient code One solution that I introduced some time ago was ad ding alternative names for condition options in IF COM so that one could force the more powerful transient processing to be The Computer Journal Issue 827 performed even when the function was supported by the resident FCP The trick was to use condition names in IF COM that were different from the names of the same functions in the FCP module Specifically I changed the first letters to X for example XXIST for EXIST and XNPUT for INPUT Frank Gaude in the Echelon Z News has reported examples in which the transient program is given a name other than IF COM such as IF13 COM Then the command INPUT gives resident processing and 13 INPUT transient processing This will work correctly for first level IF processing but will not work in general Neither of these solutions was really satisfactory A proper solution I felt wou
41. to that specified This algorithm is quick since it uses only integer arithmetic to calculate which pixels are part of the line and avoids the stair step effect which plagues other integer based line drawing routines An extended discussion of this routine can be found in Foley and Van Dam pg 433 436 see References section below The clip function is used to clip a line segment to a win dow so that no time is wasted in calculating pixel positions which fall outside the window and are not displayed The fun ction uses the Cohen Sutherland clipping algorithm see Newman and Sproull pg 65 67 to calculate the length of the line which is visible within the window in this case the window is the same as the physical screen the viewport This clipping is an iterative process where the line is successively truncated until both endpoints of the line are within the window The fun ction code returns the 4 byte values which are used to deter mine when the line is within the window In addition the clipO function tests for the situation where line clipping results in a line where both end points are on the same side of the window and are external to it In this case the line cannot be displayed and the function returns The Computer Journal Issue 27 Listing 1 Header File For Graphics Primitives A ey RN ER SS ah SE ARP ESA ERNE header file for graphic primitives void grat 14110 lt stdlib h gt lt stdio h gt
42. to use or invoke an option I will admit that any user will probably always like their first system and first wordprocessor but these new unit didn t really look at the old unit and build on their good or bad options Some of these new units handle text better than Wor dstar for desktop publishing options like multicolumn formating but overall I feel the programmers got impressed by the options available and went crazy This going crazy with options and technology is really what I want to talk about I just finished reading the last issue of Computer Journal and feel that what Art was trying to say and what I just talked about are related In the early days computers did very little and anything that worked was wonderful Most of us bought systems just to see what could be done That time is gone now althought I still buy systems to check out more later but I basically buy them to use for some productive work When doing wor dprocesing which is approximately 70 of all computer use I want something which allows me to write easily and quickly without a lot of hand movement Now all these extra bells and whistles are nice as long as they don t stop me from doing the original objective writing I have found that statement to be true also for operating systems as well as com puter languages I think anybody who has used Turbo Pascal to write a program will say that one of its best features is the ease with which you can use
43. which is not ob vious will seldom be found in any of the target system s technical data It is one of many circumstances which make dealing with alien disk formats frustrating Bits two and three define the size of the disk s allocation block The E disk supports four options of allocation size 2K 4K and 8K Other allocation sizes will require change of disk handling algorithms Bits one and zero define the size of the sectors Remember we are not speaking of 128 byte units Those are records We are referring to the physical size of the disk sector An examination of the E disk parameter block will show that it is a standard DPB Following the DPB is a group of con stants which are called the skew translation table This far our theory has been a logical one with small details inferring that everything on the disk is in a neat order Think again nothing comes this easy If it did we would be flooded with articles like these The term skew means that consecutive groups of data are not placed on consecutive sectors within a disk track Data which should logically follow one another are separated by some predefined number of sectors Dropping a record every few sectors improves disk performan ce Disk access is already slow and all tricks possible are used to improve access times The philosophy of the skew is that it takes time for the processor to deal with data This time factor is suc
44. you think will hap pen if we define our DO alias as follows EDIT 1 280 AL 1 Do you think that will work One alias inside another Well it will indeed Aliases can be nested How deeply Without any limit Before we explain why this is let s look at an even more fascinating example When I sit down to work on a program I typically go through one edit assemble cycle after another just don t seem to be able to get it right the first time So Imake my DO alias have the following script EDIT 1 280 AL 1 DO 1 This alias actually invokes itself When one cycle is finished it just goes back for more Now let s look at what goes on in the system after we enter the command MYPROG The DO alias expands its script and writes the following command line into the multiple command line buffer EDIT MYPROG Z80 AL MYPROG DO MYPROG After the editing is finished AL runs expands its script and fills the command line buffer with the following command line ZAS MYPROG IF ERROR MLOAD MYPROG FI DO MYPROG Note that the alias always appends to its own script any other commands in the command line after itself hence the DO MYPROG on the end Now ZAS runs and depending on whether there were errors or not MLOAD may run Finally ZCPR3 gets to the DO command and we are right back where we started The whole process is repeated and repeated again In fact the only trouble with this alias is that there is no way out You can
45. 52B13 1 95 Jameco EEPROM See Byte February 1984 pages 343 344 The sof tware which does not exist yet is to be completely dumped from a CP M machine over the parallel or serial ports This is to be a ROMless computer If the builder user does not have a EPROM Programmer handy the entire program could be dumped from disk into the RAM or EEPROM by way of a full computer Thus far the needs for the software areas follows Warm boot and reset commands to initialize the system There should be some user commands to set up the ports for data collection These will be in English on the screen but the responses will cause the host computer to send appropriate machine language in structions to the Z 80 board These will be in the form of Port 0 is to be examined every A MINUTE B HOUR C DAY Answering this question sets the timer function to collect data from port 0 at the appropriate interval and store it in RAM memory The menu would also have items like To return data enter D RETURN At this time the small board would dump the RAM data into the host Using the EEPROM makes the operating system non volatile and easily upgraded The entire assembly process could be supplied on a disk I have the wire list and component layout for wire wrap in a WordStar format now I don t see why it could not be put in a CP M file like README TYP Anyone building this should buy the book Some of the items s
46. 56 10 512 11 1024 Bit 76545210 TYPETAB DEFS 4 DEFB OE6H disk type byte kaypro 4 84 default EPARM DEFW 28H sec trk DEFB 4 block shift DEFB OFH block mask DEFB 1 extent mask DEFW OC4H disk size 1 OEFW directory max 1 DEFB OCOH alloc 0 DEFB 0 alloc 1 DEFW 16 check size DEFW 1 offset EDSO DEFB 1 default drive drive b default value translate table for emulator drive XLTI 0 1 2 3 4 5 6 7 8 9 DEFS 10 Listing Two Tool To Determine Disk Parameters DI SKPRAM ASM DISKPRAM intended use 15 to determine the the values of the DISK PARAMETER BLOCK and the SKEW TRANSLATION TABLE of a system alien to Ampro MULTIDSK program After the host system parameters are are determined ESET may be used to set up the E drive on the AMPRO system DISKPRAM displays the disk parameter block and the skew translation table maintained in the target blos in any selected system ee ee we we we 148 enss 4ejndWOD DISKPRAM is the combination of DPB ASM and SKEW ASM by Robert Kuhman Sysop of the Cro s Nest RCP M Revisions V1 00 as of 27 10 84 V1 01 as of 07 08 86 BOOT 0 BOOS EQU 05H EQu 5CH Other equates ACROSS EQU 8 empro blos disk Id save area 5 11 equates BELL 07H TAB EQU 09H LF EQU OAH CR EQU OOH SPC EQu 20H ORG 100H START LO HL O ADD HL SP LD SP STACK PUSH HL TEST 10
47. Adapter BOOKSH ELF M Series Fast Compact High Quality Easy to use CP M System Priced from 895 00 10MB System Only 1645 00 Ready to use professional CP M Comprenensive Software Included Computer system Enhanced CP M operating system Works with any RS939C ASCII with ZCPR3 terminal not included Word processing spreadsheet Network available relational database spelling checker and data encrypt Compact 7 3 x 6 5 x 10 5 inches t T MAKER Ili 125 pounds all metal construction Operator friendly shells Menu Powerful and Versatile Friendly Based on Little Board Read write and format dozens of single ooard computer floppy formats IBM PC DOS One or two 400 or 800 KB floppy KAYPRO OSBORNE MORROW drives Menu based system customization 10 M8 internal hard disk drive option DISTRIBUTORS ARGENTINA FACTORIAL S A 1 41 0018 MICROCOMPUTERS 613 500 0698 TLX 99408 BELGIUM CENTRE BRAZI CNC DAIA LEADER IIDA ELECTRONIQUE LEMPEREUR 041 23 4541 41 262 9969 TLX 041 6364 DENMARK TLX 49691 CAMADA DYNACOMP 03 66 20 20 TLX 43558 COMPUTER SYSTEMS LID 604 879 7737 FINLAND SYMMETRIC OY 0 585 329 ENGLAND QUANT SYSTEMS TLX 191394 ISRAEL ALPHA TERMINALS 01 953 8493 TLX 946240 REF 19003131 3 49 16 95 TLX 341667 SWEDEN FRANCE 1 509 1800 TLX 620893 08
48. BEGIN DISPLAY WAIT NTUTOR 1 DUP DUP NTUTOR 1 ETUTOR UNTIL CR CR 15 SPACES REPT REPEAT LAST LESSON GET NEXT LESSON CR TUTOR STORE SCREEN POINTERS THEN GOTUTOR 0 ETUTOR DUP DUP STUTOR NTUTOR GOTUTOR SCR 3 TUTOR BLK C INITIALIZE AND START THE LOOPS GET REPT 80K112586 GET GO SET NEXT GROUP OF SCREENS NTUTOR 8 TUTOR The Computer Journal Issue 27 REPT GO BACK AND REPEAT SET OF SCREENS STUTOR TUTOR START TUTOR START WITH FIRST SCREEN OF TUTOR 10 TUTOR HELP GIVE INTRO MESSAGE 6 TUTOR SCR 4 TUTOR BLK DEFINING MODULES OF BOK112186 CHP 10 TUTOR CHP2 20 TUTOR CHP3 30 TUTOR CHP4 40 TUTOR 5 50 TUTOR CHP6 60 TUTOR CHP7 70 TUTOR CHP8 80 TUTOR CHP9 90 TUTOR CHP10 100 TUTOR CHP11 110 TUTOR 12 120 TUTOR SCR 5 TUTOR BLK MORE ROOM FOR LESSON WORDS bdk120186 GLOS 130 TUTOR PRTSCR CR CURRENT GET SCREEN 15 NTUTOR 8 CR REPT SCREEN OF NFORMATION IS STUTOR CR HELP SCR 46 TUTOR BLK PRINT SCREENS FOR TUTOR INFORMATION 54120186 FORTH 85 TUTOR PROGRAM AND HELP SCREENS WRITTEN BY BILL KIBLER NOV DEC 1986 ALL COMMERCIAL RIGHTS RESERVED This program is intend to help beginners and old FORTH users alike The screens contain information on FORTH 83 and are related to the recomended book STARTING FORTH by
49. D nnnn HL This allows the program to return to CP M without having to do a warm boot Thirdly certain data areas will have to be preset and then the screen will be setup with a sign on message this varies the most between programs When you disassemble a program first jump to the initialization area You will want to identify the stack area which more than likely is close to other data storage areas You Should also be able to locate the screen I O routines as the program will surely do some kind of screen output during initialization There are two common means of outputting a string of data to the screen and you want to find out which method is being used This wiil aid in the remainder of the disassembly The first way is to load the address of the string into a register pair like HL and then call a routine which outputs the characters The other way is to cali an output routine and have the string im mediately following the call instruction In either case the Strings will start with a character count byte or terminate with an unprintable character like 00 or CP M programs commonly use a dollar sign as a terminator as this is con sistent with the BDOS string output function Determine which method is being used so you can spot and comment these areas as you find them You can identify the data areas being initialized but since you probably do not know what these are used for you cannot add mea
50. D you will want to identify those areas of the program that contain data and not in Structions You can spot the larger data areas using a hexadecimal and ASCII dump of the program DDT can be used if the disassembler does not support this Message areas are quite easy to find but binary data can be hard if it is not all 00 s or 0FFH s Of special importance is the location of any address tables When disassembled these tend to show up as series of LD or other meaningless instructions Depending on the program the address table might be next to another key table For example in TURBO Pascal the editor uses an input com mand table followed by a corresponding address table Programmers tend to keep these close together as it makes it easier to write and maintain the program An important point to remember is the documentation that came with the program At times there is a wealth of infor mation here You will be particularly interested in the following items Error code and error message cross references What situations lead to the different errors Internal data structure areas Some of this information may be found in a section which details the interfacing of external programs or subroutines Program options If there are several options or swit ches available what are the defaults and how are they used Names The manual may use mnemonic names while describing an internal function For
51. ET CALL BDOS DE HEXLFT RRA make left nibble POP RRA RET RRA RRA 2 PUSH HL display 16 bit Integer INC HL HEXRHT ANO OF H make right nibble CALL OAH SP HL JP C HEXLR CALL CVTI ADD A A 3AH POP HL RET HEXLR ADD A 0 5 RET LO A HL display byte at hi INC HL suboutrine to return the hex value of a CVTIA CALL HEXBYT a czascli display least significant half In c most significant in a LO DE A used when ascii hex 15 to be stored INC DE 42i nss 19 PoP RET subroutine to bit set COSTR LD CALL LO RLCA RET INC JP H blos service 8105 PUSH PUSH LD ADD 10 PUSH 10 JP BIORET POP POP RET AF write bytes addressed by hl terminated by last byte with COUT A CHL get byte print again and test for bit 7 set yes return HL next byte COSTR and continue offset in BC HL BOOT 1 get warm boot address A L add offset to wboot L A to address of service HL save it HL BIORET return address SP HL HL DE BC message strings DSPLAY DEFB DEFS DEFB DEFB DEFS OEFB DEFB BSH DEFS DEFB DEFB BLM DEFS OEFB DEFB DEFS DEFB DEFB DEFS DEFB DEFB DEFS DEFB DEFB DEFS DEFB DEFB DEFS DEFB DEFB DEFS DRIVE SPT EXM t CR LF OISK PARAMETER BLOC
52. IF is a quick way to reinitialize the flow control system and it takes very little code in the FCP ZSIG Diskette 1 Now that I have atoned I hope for my sin in the last issue I will turn to the first new subject the inaugural ZSIG diskette Let me remind you that this diskette and a number of others put out by NAOG ZSIG NAOG North American One Eighty Group the group formed to support the SB180 computer and other computers using the Hitachi HD64180 microprocessor can be ordered from NAOG ZSIG Box 2781 Warminster PA 18974 I encourage all of you to join ZSIG 15 You ll get a nice newletter with Z System tips and details on all the NAOG ZSIG diskettes Here is a listing of the files in ZSIG diskette 1 Z RIP LBR VERROR17 LBR VCED18 LBR ZCRCK LBR ZFINDU LBR ZLDIR LBR ZTXTTOWS LBR ZWC LBR PPIP14 LBR UF LBR LDSK20 LBR W20 LBR The first three programs are by Paul Pomerleau Paul is a speed freak and like many of us found the process of installing Z programs with Z3INS the standard installation utility tedious and slow So Paul wrote Z RIP given that name because it rips through an entire disk of files at incredible speed automatically identifying the ZCPR programs and installing them The new autoinstall versions of ZCPR3 may make Z RIP not to mention Z3INS obsolete but it is great for those running standard ZCPR VERROR is Paul s video error handler It provides a screen display of the entire command lin
53. Issue Number 15 Interfacing the 6522 to the Apple II Interfacing Tips amp Troubles Building a Poor Man s Logic Analyzer Controlling the Hayes Micromodem II From Assembly Language Part 2 The State of the Industry Lowering Power Consumption in 8 Floppy Disk Drives BASE Part Three Issue Number 16 Debugging 8087 Code Using the Apple Game Port BASE Part Four Using the S 100 Bus and the 68008 CPU Interfacing Tips amp Troubles Build a Jellybean Logic to RS232 Converter Number 17 Poor Man s Distributed Processing BASE Part Five FAX 64 Facsimile Pictures on a Micro The Computer Corner Interfacing Tips amp Troubles Memory Mapped 1 O on the ZX81 Issue Number 18 Interface for Apple Game ort The Hacker s MAC A Letter from Lee Felsenstein S 100 Graphics Screen Dump The LS 100 Disk Simulator Kit BASE Part Six Interfacing Tips amp Troubles Com municating with Telephone Tone Con trol Part 1 The Computer Corner Issue Number 19 Using The Extensibility of Forth Extended CBIOS A 500 Superbrain Computer BASE Part Seven Interfacing Tips amp Troubles Com municating with Telephone Tone Con trol Part 2 Multitasking and Windows with CP M A Review of MTBASIC The Computer Corner Issue Number 20 Designing an 8035 SBC Using Apple Graphics from CP M Turbo Pascal Controis Apple Graphic
54. K for drive 1 SPT 4 H TAB Records Per Track CR LF BSH 1 2 Shift Factor CR LF BLM 2 H TAB Block Mask CR LF 2 H TAB Extent Mask CR LF OSM 4 H TAB Disk 51 26 1 8 1 ORM 4 H TAB Directory Size 1 CR LF ASVO 2 H TAB Al location Vector CR LF ALVI 2 H TAB CR LF CKS 4 DEFB DEFB DEFS DEFB OFF DMPMSG DEFB DEFB NXLATE TBLMSG OEFB OPH DEFB User help HEXBYT PUSH CALL LD POP CALL RET subroutine to OUT PUSH PUSH PUSH AND LO LD CALL POP POP POP RET H TAB Oirectory Check size CR LF OFF 4 TAB Offset Number of reserved tracks CR LF LF DPB address and hex dump of table CR LF 80H BELL Diskette needs no translation CR LF 80H Skew table decimal values CR LF 80H address CR LF 80H AF save HEXRHT get right nibble C A save inc AF restore and get HEXLF T left nibble write a to console BC DE HL strip bit 7 E A C 2 cp m fcn 2 BOOS HL DE BC to the console PUSH LO CALL LO CALL POP RET AF A CR COUT A LF COUT AF carriage return print it line feed and print it subroutine to write a space to the console gt PUSH LD CALL DEFB DEF8 DEFB DEFB DEFB DEFB
55. LIB and VLIB A must for any serious user of these programming tools Loose leaf notebook style easy to work with as it will lay flat on your desk THERE S MORE We couldn t fit all Echelon has to offer on a single page you see how small this type is We haven t begun to talk about the many additional software packages and publications we offer Send in the order form below and just check the Requesting Literature box for more information ftem Name Price 1 ZCPR3 Core instalianon Package 44 00 3 disks 2 ZCPR3Utimes Package 89 00 9 disks 3 Z3 Dot Com Auto Install ZCPR3 99 00 6 disks 4 Z3 Dot Com Bare Minimum 49 95 1 disk 5 2 Auto instali 2 System 119 00 7 disks 6 Z Com Bare Minimum 69 95 2 disks 12 PUBLIC ZRDOS Plus by tsetf 59 50 1 disk 13 Kaypro Z System Bootable Disk 69 95 3 disks 20 ZAS ZLINK Macro Assembler and Linker 69 00 1 disk 21 ZOM Debugger tor 8080 ZB0 HD64 180 CPU s 50 00 1 disk 22 Transiators tor Assembler Source Code 51 00 1 disk 23 REVAS3 4 Orsassembier 90 00 1 disk 24 Special hems 20 through 23 150 00 4 disks 25 050 80 Full Screen Debugger 129 95 1 disk 27 The Libranes SYSLIB 231 and VLIB 69 00 8 disks 28 Graphics and Windows Libranes 49 00 1 disk 29 Special 27 28 and 82 129 00 9 disks 40 Input Output Recorder 1OP VOR 39 95 1 disk 41 Background Pnnter BPrinter 39 95 1 disk 42 Program
56. LTO 0 0 0 DIRBUF OPARM CSV2 ALV2 XLTO 0 0 0 DIRBUF OPARM CSV3 ALV3 XLT1 0 0 0 the e disk DIRBUF EPARM CSV4 ALV4 40 4 15 1 94 65 128 0 16 2 40 4 15 1 194 127 192 0 52 2 40 single sided ampro disk sec trk block shift block mask extent mask disk size 1 directory max alloc 0 alloc 1 check size offset 3a double sided ampro disk sec trk block shift block mask extent mask disk size 1 directory max alloc 0 alloc 1 check size offset 96 tpl double sided sec trk DEFB 4 block shift DEFB 15 block mask DEFB o extent mask OEFW 394 disk slze 1 DEFW 255 directory max DEFB 240 alloc 0 DEFB 0 alloc DEFW 64 check size DEFW 2 sof tset XL TO 48 tpl skew table OEFB 1 2 3 4 5 6 7 8 9 10 call to bios function getedisk returns the address of eparm the type table entry 15 returned as the value returned of the eparm 1 the translation table location is defined as the returned value tl5 the following definitions set the emulator disk as a kaypro 4 10 kaypro 84 series as the default system to be emulated drive b 15 the default emulator drive these values may be altered using the ampro multidsk com utility 1 Bit 76543210 Density x O single 1 double Sides x O single l double Sector s x 0 5 12 nuous Track count x O down t down front up back Alloc unit OO IK 01 2K 10 4K 11 8 Sector size xx 00 128 01 2
57. Leo Brodie which can be used as a textbook with this program Each chapter or series of screens is organized to present the words used in the chapter first in a glossary form Old timmers will find this glossary important to see the differences between F83 and other versions Typing HELP will repeat these screens then typing SCR 7 TUTOR BLK second intro screen with list of words bdk 120186 the chapter number for the area of help needed Typing ESC key will exit the screens and return to the system prompt GET will display next chapter of information while REPT will start with tne first screen of the chapter again START TUTOR will start with the first chapter Display will pause until SPACE BAR is pressed NEW F83 WORDS The Computer Journal Issue 27 of 60 characters by 16 rows which at first I felt too small for the tutor program Af ter generating some text I found the size actually to be a very nice presentation The borders and display shouid be usabie on any machine one of Forth s strong points The other words merely set which screens to load and where you started The only major word I defined was ac tually modifiying the Forth LIST word Normally using LIST will display a screen with each line numbered and with line 0 containing the origination date and the title I wanted the starting title and no line 0 or line numbers What I did was reproduce the original F83 LIST definition and then remove or r
58. License additional modules FORTHCOM DATAHANDLER PLUS PC only 128K req FORTHWRITE word processor Corporate Site License Extensions Bulk Distribution trom 500 50 units eSome recommended Forth books FORTH A TEXT REF besi text 1895 THINKING FORTH best on technique 16 95 STARTING FORTH popular text Shipping handiing 5 tax extra No returns on software Ask your dealer to show you the world of MMSFORTH or request our free brochure MILLER MICROCOMPUTER SERVICES 61 Lake Shore Road Natick MA 01760 617 653 6136 Listing 1 3 HD64180 Ports cntia0 equ 0 ASCI Control Reg Chnl 0 cntlal equ 1 ASCI Control Reg A Chnl 1 cntlbO equ 2 ASC Control Reg B Chni O cntibl equ 3 ASC Contro Reg B Chni 1 statO equ 4 ASC Status Reg Chnl 0 stat equ 5 ASCI Status Reg Chnl 1 equ 6 ASCI Transmit Data Reg Chnl 0 tdri equ 7 ASC Transmit Data Reg Chni 1 8 ASC Receive Data Reg Chn 0 equ 9 ASC Receive Data Reg Chnl 1 Clocked Serial Input Output Port CSI O centr equ Oah 51 0 Control Reg trdr equ Obh CSI O Transmi t Receive Data Reg Programmable Reload Timer PRT tmdrOl equ Och PRT Timer Data Reg Chn 0 Low tmdrOh equ Odh PRT Timer Data Reg Chnl 0 High rldrO equ PRT Timer Reload Reg Chnl 0 Low ridrOh equ Ofh PRT Timer Reload Reg Chnl O High tcr equ 10h PRT Timer Control Reg tmdrii equ 14h PRT Timer Data Reg Chn
59. OM BIOS boots DOS 2x and 3x Hard Disk support OPTIONS PROJECT BOARD 186 adas 25 square inches of ware wrap prototype area with buffered and pre decoded 80186 bus interface for Little Board 186 VIDEO RAM EMULATOR allows use of software that writes to display controller VIDEO RAM ARGENTINA FACTORIAL S A 41 0018 TLX 99408 AUSTRALIA ASP MICROCOMPUTERS 613 500 0698 TLX 36587 BELGIUM CENTRE ELECTRONIQUE LEMPEREUR 041 23 45 41 TLX 49691 SRAZI COMPULEADER COMPUTADORES LTOA 41 269 1939 TLX 416139 CANADA 604 438 9019 DENMARK DANBIT EXPANSION 186 adds five key options to Little Board 186 512K RAM 8087 co processor Battery oacked Real Time Clock 2 RS232 422 sync async serial ports 1 0 expansion bus 03 66 20 90 TLX 43558 Ul SYSTEMS LTD 0296 35511 837447 FINLAND SYMMETRIC OY 358 0 385 399 121394 FRANCE PLUS 1 4509 1800 TLX 690803 ALPHA TERMINALS LTD 03 4 amp 95 LX 341667 SWEDEN 08 54 90 20 13702 USA CONTACT AMPRO COMPUTERS INC MO Coro 80188 Corp COMPUTERS INCORPORATED 67 East Evelyn Ave Mountain View 94041 415 968 0830 TELEX 4940302 FAX 415 969 1049 Since you want Common Area 1 to start at 8000H you would set up the 4 most significant bits of CBAR as 1000H To see how the value was obtained just do the following Starting a
60. PRAM program source code and object code files plus other related files are available on eight bit 5 25 AMPRO Kaypro Morrow and several other popular for mats for 10 postpaid in the U S 51 THE COMPUTER CORNER Column by Bill Kibler Well here I sit before my new com puter on Thanksgiving Day putting down my thoughts before I forget them You might think I am at my home but no I am at my mother s waiting for the rest of the family to arrive The machine I am using is my new Heath Zenith 1719 table PC This is the same unit the IRS bought and yea the same one that Morrow sold to ZDS for a small sum of money without any royalities I needed the machine for my college work and it is my only PC compatible machine and will be the only one too Thanks to some friends of mine I was able to pick it up for much less than the going price but even then the unit is a bit expensive for what you get I have found the keyboard to be very good in fact I like it better than any PC or PC clone s keyboard I have tried After getting this I noticed how far apart most of the other keyboards keys were PC types What all this is leading into is my increased use and knowledge of PC programs My masters work is moving along well and most of the work I am doing now is on PCs with PC type programs What I have found out so far is the current trend in PC programs use of the function and cursor keys exclusively I must a
61. Programming User Support Applications Issue 27 68000 TinyGiant Low Cost 16 bit SBC and Operating System The Art of Source Code Generation Disassembling Z 80 Software Feedback Control System Analysis Using Root Locus Analysis and Feedback Loop Compensation The Hitachi HD64180 New Life for 8 bit Systems A Tutor Program for Forth Writing a Forth Tutor in Forth Disk Parameters Modifying The CP M Disk Parameter Block for Foreign Disk Formats ISSN 0748 9331 THE COMPUTER JOURNAL 190 Sullivan Crossroad Columbia Falls Montana 59912 406 257 9119 Editor Publisher Art Carlson Art Director Donna Carlson Production Assistant Judie Overbeek Circulation Donna Carlson Contributing Editors C Thomas Hilton Donald Howes Jerry Houston Bill Kibler Rick Lehrbaum Peter Ruber Jay Sage Jon Schneider Entire contents copyright 1987 by The Computer Journal Subscription rates 16 year 6 issues or 28 two years 12 issues in the U S 22 one year in Canada and Mexico and 24 sur face for one year in other coun tries All funds must be in US dollars on a US bank Send subscriptions renewals or address changes to The Computer Journal 190 Sullivan Crossroad Columbia Falls Montana 59912 or The Computer Journal PO Box 1697 Kalispell MT 59903 Bulletin Board Our bulletin board will be on line 24 hours a day at 300 and 1200 baud and the number is 406 752 1038 Add
62. RUNZ support this alias type It works the same as a regular alias except for one thing it does not append to the script expansion any commands that were pending in the command line buffer it just throws them away Thus in the above example all the FIs would be discarded when DO was invoked again and the pileup would be avoided When an alias is created with VALIAS one can select either a normal alias or a recursive alias But note that no other com mand can ever follow a recursive alias on a multiple command line Recursive aliases should be used only in special cases like the one described here Shells Aliases are not the only command line generators Most shells also generate command lines for the user In some cases VCED described above and MENU this is their main pur pose in other cases it is secondary VFILER Before we examine the way they generate command lines let s look at the way shells operate in the Z System The essential purpose of shells is to create just the kind of recursive command situation we were just developing with our alias example But they achieve that function in a very different way A shell has a kind of schizophrenic personality as a result of being invoked in two significantly different circumstances One circumstance is when it is invoked directly or indirectly e g from an alias as the result of a user command In this case the shell has one basic purpose to perpetuate its own existence as
63. SS 36 by Jay Sage semen 28 Editor s Page Market Developments While some people claim that the per sonal computer sales are flat because the sales of their own products are low and others claim that the technology is stagnate because all they see is the IBM PC series there is actually a great deal of activity in both sales of existing products and technical developments which will lead to the next generation of computers If anyone tells you that computers aren t selling show them the current issue of Computer Shopper which has 408 pages mostly filled with ads for har dware and software Many of these ad vertisers have been running full page or even multipage ads in every issue and those I talk to assure me that the ads are generating the sales to justify the cost of the ads they re selling a lot of har dware software and peripherals but the market has made another abrupt change As pointed out in George Morrow s column in Electronic Engineering Times January 12 1987 page 61 individuals started buying again in 1986 while the corporations and government agencies cut way back on their purchases To quote one small sec tion of his column personal com puter market was launched by in dividuals who were convinced that the power of low cost micros could be har nessed to solve spreadsheet applications and word processing chores and it s no secret that this type of customer doesn t use
64. V Engineering Closed loop feedback control systems are used to ensure that an activity occurs as intended All such systems contain a forward block which performs an action and a feedback block which measures the action and reports the results The function of the feedback loop is to reduce the error between the measured and desired result to zero or some acceptable value near zero Figure 1 shows a typical feedback control system in its simplest form Figure 1 Simplest Feedback Control Loop The composite LaPlace transfer function H s of the feed back system of Figure 1 can easily be calculated If G s is the LaPLace transfer function of the forward path and K s is the transfer function of the feedback path and the overall transfer function H s is defined to be H s Y s X s then Y s e G s 1 e X s 5 5 2 Substituting 2 into 1 gives Y s 2 G s X s K s s 1 3 Rearanging 3 gives us the answer for the closed loop transfer function H s Y s X s G s 1 K s G s 1 4 An example of such a control system is the driver of an automobile In the case of the driver he uses the automobile controls to maintain the vehicle on a desired path The driver s vision provides a means for sensing the actual motion while his brain derives the error between the desired motion and the ac tual motion Deviations are corrected the new path observed and a new estimate of the error be
65. a command It does this by entering its name as a command into a special buffer area in memory in the Z System called the shell stack Having done that it can then return control to the operating system The smarter shells generally do something a little more sophisticated at this point but the principle is correct as I have described it Now we come to the unique role of shells in the Z System The CP M command processor gets commands from only two possible sources 1 from a submit file if one exists or 2 from the user The Z System gets commands from at least four sour ces and in the following order of priority ignoring the tricky role of ZEX 1 from the multiple command line buffer 2 from a submit file 3 from the shell stack and 4 if all else fails from the user Observe that so long as the shell stack has a command in it the command processor will never turn to the The Computer Journal Issue 27 user for input That is why one can regard the shell as taking over the command processor function While the shell is run ning it becomes the source of commands for the system How does the shell do this By expressing its second and more dramatic personality Another special buffer in the Z System the message buffer contains a flag byte that is set by the ZCPR3 command processor to indicate whether a program has been invoked as a user command or as a shell or as an error handler We have already discussed the simple goa
66. acter 1 3 set flag for non zero character 2 10 B OFFH set to zero JP COUT print RET 42i ONGS 1 print record entry LD A C LO DE A INC DE PRINT CALL HEXADR print hi as hex words RET CALL COSPAC Insert space LD A NPRINT see if end of line Subroutine to do an addressed dump of one line HL point to data DEC A B has length LO NPRINT A update 5 RET NZ CALL HEXADR display hl contents in hex 10 A ACROSS how many lines across LD Ari 10 NPRINT A save CALL COUT CAN COCRLF start new line CALL COSPAC 4 HEXLIN PUSH BC select disk has drive number PUSH HL j HEXL2 LO A HL 14 PUSH BC CALL COHEX display hl hex PUSH CALL COSPAC space PUSH HL INC HL LD C 14 CALL BOOS DEC B POP HL JP NZ HEXL2 POP DE POP HL POP BC POP BC RET RET b get current disk number returns current disk in a Subroutine to print hl as an address in hex 5 25 PUSH BC HEXADR LD A H PUSH DE CALL COHEX PUSH HL LD Lo 25 no drive given get current disk CALL COHEX CALL BOOS RET POP 3 print the hex byte In a POP BC RET COHEX PUSH AF save byte i CALL HEXLFT get left half get disk parameters returns hi sdpb address CALL COUT and print i POP AF restore byte FCN3t PUSH BC CALL HEXRHT 3 right half and PUSH DE CALL COUT print 10 C 31 hl dpb for current disk R
67. ader s feedback is VERY important and we encourage every reader to send us a list by mail or on the BBS describing the four subjects that they would like to have covered in future articles A Computer Builder Issue 426 just arrived and I read it cover to cover Ironically last week some back issues of TCJ and The Big One you know the magazine with 300 pages of advertising been around for ten years arrived I just threw away several years worth of old computer magazines and comparing the two which arrived on the same day I found what was missing in computer literature I sincerely hope you can keep up what you have so The Computer Journal Issue 427 diligently started I have a North Star Z80A Processor Board model ZPBA2 copyright 1977 It is in an IMSAI computer and has developed a minor glitch I have schematics on everything else do you know where I might find the processor board schematics You mentioned I believe in a previous issue that you would like to have a library of old schematics and instruc tions for various archaic systems If this is true I can offer copies of the Big Board I I have two working boards to possibly selD the Tarbell Casette interface board VDB A Video Terminal S 100 card Jade Z 80 actually Ithica Z 80 and an Ithica Audio board with the working mod s on it and the Xitex SCT 100 Single Card Video Terminal Right now I am in the final stages of construction on a ZAP 80 m
68. al to see TWO THOUSAND The Computer Journal Issue 427 TRACKS reserved on LOGICAL DRIVE D This offset value is used to partition a large hard disk into more bite sized portions compatible with the various limitations of disk space management Adding 2000 tracks to a record number points to the directory tracks on logical drive D of the hard disk This is a good way to find your way around the void of a large disk system The DOS assumes there are four physical disk drives A B C and D connected to the system The BIOS knows there is only one physical drive What the DOS does not know will not hurt it The Reality of the Situation A full description of how to apply the variables we have just discussed would be beyond the scope of what we wish to achieve and the design of each reader s disk would be different Each would make different trade offs according to his needs opinions phase of the moon and other factors unmentionable in print The results of these decisions the values placed in the DPB and the many algorithms which would be required to sup port them would be called DISK FORMATS and each of them would be incompatible with another s Are you beginning to get the picture on why there are so many different disk formats and why no wishes to second guess the thoughts of the author of a BIOS The BIOS is the only portion of the operating system which speaks directly to the system hardware and the only program u
69. allable Dealer inquiries welcomed Turbo Pascal Advanced Applications 17 The C Column A Graphics Primitive Package by Donald Howes pn Its now December 18 and I m frantically typing this column so I can leave on the 20th to go to Canada for Christmas By the time you read this the holiday season will have passed I hope that it has been a happy one for all Hopefully I won t still be chained to this desk In this column I ll start to present code for a graphics primitive package for the IBM PC While these particular primitives are for that machine it shouldn t be hard to adapt the code to run on other machines either MS DOS based or other operating systems Once the primitives are complete which will be this and the next column we can take a stab at developing some applications using them By hiding the machine dependent code at the lowest level it will free us to develop the important things in a more general and machine independent fashion aiding in the porting of our software from one system to another This time present code for the most basic parts of the primitive package These routines initialize and terminate the application provide move and draw routines and the ability to activate a pixel and clip a line see Listings 1 and 2 Getting Things Started and Stopped To start things off it is necessary to initialize the graphics applicati
70. also work and are available at very low prices The software that comes with the TinyGiant has many features that will remind you of CP M or MS DOS The disks are compatible with MS DOS which means that you can move data files from your new machine to your PC easily The stan dard command processor is modeled after MS DOS but does not have batch files The editor is a line editor but is much better than ED or EDLIN The assembler is a two pass absolute assembler that has include files but no macros The compiler is for HTPL the language used to write the K OS ONE operating system People who currently use a Z 80 and are interested in moving up will be interested in the board Also anyone who wan ts to learn about the 68000 without having to dig through a dif ficult operating system will like it The price of the board is competitive with the 80 and 86 family boards and so is the price of the software The small size and power make it great for con trol applications The use of MS DOS compatible disks makes it very convenient for data capture The operating system makes it good for a personal computer or for experimenting At the present time there are a limited number of programs that will run under K OS ONE This will improve in the next few months as the companies that purchased the first copies of K OS ONE bring their products to market For any new system there is a delay between when it is first delivered and when lots of sof tw
71. are is available for it Some of the software that will be available is code that is being ported from other systems For languages there is the assembler and the HTPL com piler that come with the basic machine and the operating system is written in HTPL so that it can be recompiled on the system Most of the development is being done in HTPL but the source code for the runtime library is written in assembler and is supplied in source form For many applications most of the code can be written in HTPL with the speed critical portions written in assembler Also there are some functions that are much easier to write or much smaller in assembler I under stand that a C compiler is being ported over to the system Externally the operating system can look like anything you want it to The command processor provided looks a lot like MS DOS but you can change it because it is a separate program like the CCP is in CP M and you are provided with the source code In a dedicated application the command processor could be replaced by a menu to load a set of application programs A command processor could also be written that would make it look like a Unix system was being used if that was desired Internally the operating system resembles Unix or MS DOS 2 0 except that it is greatly simplified All system calls are done in a manner similar to MS DOS where the required infor mation is placed in a parameter block and then a trap instruc tion gives con
72. ate locations The hardest part of making these ZCPR3 versions of the CP M programs was stripping out the complex and lengthy parsers required to accept DU syntax in CP M So much for the myth of ZCPR3 complexity Programming in ZCPR3 is often as in this example simpler than programming in standard CP M The third group of programs includes two more ZCPR3 ver sions of CP M programs They are listed separately only because they do not have names with Zs in front Here is a quick listing of the functions of all seven of these converted programs ZCRCK computes cyclic redundancy check codes for files using both common CRC polynomials ZFINDU searches for text strings in files including files that are squeezed ZLDIR displays a directory of the files in a library ZTXTTOWS converts standard text files to WordStar files ZWC counts the number of words in a text file PPIPM copies files as does PIP but with nicer interface and fast Irenamed it to COPY and use it all the time UF Steven Greenberg s ultrafast file unsqueezer The last two programs are original creations for the Z System LDSK by Wilson Bent with modifications by Earl Boone solves a longstanding problem that owners of floppy disk based computers had with named directories With hard disks there is an unchanging association between directory names and drive user values but with floppies the association changes every time the diskette is changed
73. by ALIAS VALIAS TALIAS or BALIAS thetext file based alias generator ARUNZ with its ALIAS CMD file the menu or macro type shells MENU VMENU FMANAGER VFILER and ZFILER and the command line history shells HSH and VCED Plans for Next Time As I said at the beginning of the article I had planned to cover along with all the subjects above techniques for customizing the Z COM self installing version of Z System But there just isn t the time or space So I will have to leave that for the next issue Let me just say one thing here If you do not already have Z System running on your computer and have held back on buying Z COM from Echelon because you thought it would not offer you the flexibility of a custom installation hold off no longer Buy Z COM Start the exhilarating process of discovering Z System now By the time my discussion of Z COM hacking is complete you will know how to get just as much flexibility with Z COM as with a manually installed version It is much more fun to start with something that is working and to improve it than it is to spend many frustrating weeks trying to get an initial manual version working I want to close with my usual invitation and encouragement please write and with your comments and suggestions of all kinds B b Over 15 000 of these board computers installed Free copy of the MORROW OWNERS REVIEW The national m magazine devoted just to the ORROW computer
74. ctua Echelon Inc Cost esewhere Specify disk format 885 N San Antonio Road Los Altos CA 94022 415 948 3820 Order line and tech support Telex 4931646 11 LO HL F1lelO INC HL JP HL Address of general file i o Change INC into DEC for reading Execute and return through it While this type of code would be difficult to manage because it would have to remember the last state it could be made to function Relocatable Code The Z 80 does not process relocatable code So the program must handle the relocation task itself before it is executed While there are many ways to do this the most common procedure to to maintain a table of those address that have to be relocated TURBO Pascal in the overlay command processor TURBO OVR uses this technique The program is assembled as if it begins at location zero or some such address Just prior to being executed a relocation routine moves it to the destination address in the case of TURBO OVR this is high memory and then changes all address references accordingly Finally the program is executed A second procedure is to maintain a bit map table within the program some assemblers help you maintain such a table This table has a bit for every byte in the program If the bit is set the corresponding byte must be relocated This works for programs which are relocated by a certain number of pages 256 bytes to a page That way only the high byte of an address must be c
75. d correct your mistake There are plenty of other tricks you may run into and some are even more obscure Making Use of the Generated Source Code Now that you have generated the source code and it has been documented more of less to your liking what do you do with it Although you probably should have asked yourself this before you started this project here is a list of the major uses for the source code to a program Using the source code you can fix those bugs that preven ted you from fully utilizing the product Set those default parameters to what you want Modify the program to include features that you and perhaps others want to see Learn how the programmer did those wonderful things Make your programs work just as well using these techniques Make some money from your labor Because you have converted the program from machine code to an ASCII file suitable for an assembler you can now edit the file making any changes you wish Then you reassemble and link or load the program This new copy now functions the way you want it to If one of your reasons for producing the source code was to learn how the program functioned then the printed listing is probably the most important result While the process of disassembling already gave you great insight into the program as a whole now you will be able to study that particular aspect that intrigued you like just how does TURBO Pascal handle a forwar
76. d label reference when it is only a one pass compiler Is it really a one pass compiler Another interesting but often overlooked use for the source code is that other people may have similar interests to yours Maybe you could sell it This is a sticky area because the source code is composed of instructions whose order ie the executable part of the program is owned by the author plus your added comments and label names There have been a few examples of disassembled programs being published for example the Timex Sinclair ROM but these most likely required the con sent of the original author Regarding your work you would certainly be allowed to sell your label names and comments but probably not the instruc tions After all if you sold the instructions then you are in effect selling the program and would owe the author royalties But all is not lost as there is a way out of this mess If you consider that every line of the assembly source file looks like this lt f 42 gt 5 gt j4 LabeiName processor instruction instruction arguments Comments where each field could be absent then you could extract the por tions that you have created 1 and 4 from the line and eliminate the portions that the program author created 42 and 43 The extracted portions could be put into data files and sold Now in order for a customer to use this data your label nam
77. dard Z80 I O instructions with the added feature of placing all 0 s on the high order 8 bits of the address bus This assures that the in struction accesses the 64180 s internal ports You will also see the MLT instruction used To use it just set up a register pair BC DE HL or SP with the values to be multiplied an 8 bit value in each 8 bit register The result will be stored as a 16 bit value in the same register pair I did not include the Disk Parameter Header nor the Disk Parameter Block for the RAM disk as they are nothing more than the standard CP M struc tures The memory maps used as exam ples in the prior text are the same ones that this RAM disk driver uses The routines are strictly the low level drivers and the high level disk routines are not shown There are already several packages that are coded to allow the programmer to access the 64180 s extra memory from within a high level language without having to worry about the complexities of addressing it at the chip level They are Borland s Modula 2 from Micro Mint and 64180 Basic from Softaid 64180 Basic is currently available and Modula 2 will soon be There has also been talk of several new CP M packages being written specifically for the 64180 one of them being a Lotus like spread sheet Echelon is currently working on a new multi tasking DOS and banked ZC PR3 that will both utilize the 64180 s memory addressing features The Computer Journa
78. ddress 8000H 8000h 1000h 4k Bh divide address by 4k OBh 1000 bin resuit to binary 4 MSB s in CBAR 1000 Since the Bank Area is to start at 0000h the 4 least significant bits of CBAR will be 0 s Then just convert 10000000b to hex and you will have a value for CBAR of 80h Now that the segments have been choosen for the 64k logical address space and set up with the CBAR register the next step is to determine what addresses in physical memory will be mapped into those segments There are two registers used for that purpose CBR and BBR MMU Common Base Register CBR 1 0 Address 38H bit 7 6 5 4 3 1 0 CB6 CBS CB3 082 CB CBO CBR specifies the base address on 4K boundaries used to generate a 19 bit physical address for Common Area 1 accesses After a reset all of the CBR bits are set to 0 MMU Bank Base Register 1 0 Address 39H bit 7 6 5 4 5 2 1 0 886 885 884 882 BB 880 BBR specifies the base address on 4K boundaries used to generate a 19 bit physical address for BanK Area accesses All bits of BBR are set to 0 after a hardware reset As an example suppose that you want to switch a block of memory starting at physical address 50000h into the Common Area 1 segment at the same time switching out whatever was there Then the CBR register would be loaded with 50h It s that simple You just load the register with the two most significant digits of a 5 digit hexadecimal a
79. ddress in physical memory DISK DRIVE SERVICE SERVICE SPECIALS Apple II Drives Shugart SA 400 400L Shugart SA 800 801 Shugart SA 850 851 DRIVES FOR SALE Shugart SA 800 2 wide frame Shugart SA 850 wide frame 525 514 DS DD full ht Tandon 100 2 DS DD full ht Apple II Drives Genuine PC floppy contr 60 day warranty on all drives and service Turnaround time usually 24 48 hours Trade in available for drives too costly to repair Prices do not include parts or shipping If parts are more than 20 we get permission before repairing Units returned UPS COD unless otherwise requested All drives for sale are reconditioned unless otherwise noted and documentation is included LDL ELECTRONICS 13392 158 St N Jupiter FL 33478 305 747 7384 The BBR register is used in exactly the same manner and since Common Area 0 always starts at physical address 0 there is no need for a register for its mapping A few examples may help to clarify all three registers usage CBAR 80h CBR 00h BBR 40h MEMORY Logical Address Physical Address FFFFh OFFFFh 32k 8000h 08000h 7FFFh ATFFFh 32k 0000h 40000h Now to switch the physical addressed memory 40000h to 47FF Fh out of the bottom 32k of logical address space and switch the next 32k block from 48000h to 4FFF Fh into the same logical address space just load BBR with 48h CBAR 80h CBR 00h BBR 48h MEMORY Logical Address Physical Address
80. dmit that my first wordprocessing program was WordStar mostly because I worked there Now I still use this program and am writing this article on it I have tried several other PC word processors and have not liked a single one of them The reason is their use of the function keys WordStar can use function keys if you want but most of the cursor movement can be made without lifting your hands from the home postion I recently spent a morth on Framework an integrated package of wordprocessing database and spreadsheet This program has some good features but for the most part I hated it It seemed every third keystroke was a function key or cursor movement key without any optional ways around them What really made me hate the program was their use of the and cur Sor position keys If you look at the key codes produced by a PC keyboard there are different key codes for every possible use of the keys The number pad can be 52 numbers cursor positioning functions as well as control and alternate options too What Framework and other programs do is use all these possible combinations to get their options Wordstar divided their options into groups and you get to those groups by doing a control key entry then use a regular key to run the option These other prorams are using a single keycode for an option This means you must have a compatible keyboard and you must also in most cases move your hands from the home keys
81. dress of the DPB is returned from the BIOS using DOS function call 31 The structure of the DPB is shown in Figure One NEW MEANING SECTORS PER TRACK BLOCK SHIFT FACTOR BLOCK MASK EXTENT MASK DISK SPACE MAXIMUM DIRECTORY MAXIMUM RECORDS PER TRACK DISK BLOCK MAXIMUM DIRECTORY NUMBER ALV INITIAL ALV MAP DRM ALO AL1 INITIAL ALLOCATION CKS CHECK AREA SIZE OFF TRACK OFFSET RESERVED TRACKS Figure One The Standard Disk Parameter Block The first byte in the DPB is the RECORDS per track parameter value Under CP M 1 4 there were 128 bytes per sec tor only This is why CP M 1 4 is no longer in use Modern technology allows several different values of SECTORS per track with 128 bytes per record within a given sector This value represents the number of RECORDS per track and has nothing to do with the number of physical sectors per track This is where the distinction lies and must be recognized if we are to battle confusion If you think in terms of sectors with every sec tor being 128 bytes then nothing will make sense from here on Think in terms of 128 byte RECORDS only The next entry in the DPB refers to the BLOCK SHIFT FACTOR Recall I mentioned the DOS doesn t know anything about sectors and tracks This is the first of several data which allow the DOS to calculate where a given record is upon the disk and demand it of the BIOS The block shift value is the number of times a given record s number should be log
82. e a new alias such as DONEW The answer is that the alias program actually does much more than just copy a com mand script as is into the multiple command line buffer It is capable of making parameter expansions the simpler examples of which are like the parameter expansions that occur with the CP M SUBMIT program We can store the alias script as EDIT 1 780 2 5 1 IF ERROR MLOAD 1 FI 31 The 1 is a symbol representing the first token after the com mand on the command line that invoked the alias program Thus when we enter the command DO MYPROG we get the first script we discussed but when we enter NEWPROG we get a command line for working on NEWPROG instead A single alias thus becomes very flexible There are quite a num ber of parameter forms that can be processed by aliases and I refer you to Rick Conn s ZCPR3 The Manual and various HELP files for more detailed information Now let s try something a little trickier Sometimes we have already edited a file and just want to assemble and load it if there is no error in assembling of course So we create an alias called AL for assemble link ZAS 1 IF ERROR MLOAD 1 FI I am using ZAS in these examples rather than the SLR Z80ASM which I prefer because the SLR assemblers can produce a COM file directly in one pass and do not need MLOAD or the flow control error checking Thus they do not serve the purposes of my example here Now what do
83. e hour generating screens to do it I only had one time in which any code went south for the winter other than that it was very painless Although this program is rather simple involving defining barely ten words it has made a real convert of me Compared to the tutor program I wrote in BASIC this was a breeze to write and will work many times better TUTOR BLK The program has three variables which keep track of the current screen Forth stores all information in screens of 1024 characters each This gives a dislay 36 SCR 0 TUTOR BLK INTRO FOR SCREEN ZERO BDK1 12186 IE HE EIE IE E 3C CE IE OE IUE HE 14515441 IEEE OE IE IEEE IE EXE EIE IEEE IE EE ES SET TPS SET A OG X EN 13332123 Lari F83 TUTOR AND HELP PROGRAM F83 TUTOR AND HELP PROGRAM 13536354 REE X 3 3 Written by Bil Kibler PASE
84. e in which an error was detected and allows the user to edit it freely moving about using WordStar like commands VCED is Paul s Video Command EDitor a video history shell With VCED run ning as a shell the user always has full command line editing In addition past commands can be recalled searched for edited and run As if that were not enough it doubles as a video error handler as well Paul astutely noted the functional similarity between correcting old commands with errors and entering new commands so he combined the two functions in a single program The next group of five programs comprises Z versions of common CP M utilities Most of these were created by the prolific program fixer and NAOG ZSIG chief Bruce Morgen The main feature that makes these programs ZCPR3 com patible is their ability to accept named directory DIR references as well as drive user DU references For programmers and aspiring programmers reading this you should know that the code to do this in ZCPR3 is actually much simpler than the CP M code needed just to recognize the DU form This is because the ZCPR3 command processor already does all the work for the first two arguments on the command line including translating named directory references into drive user values Unlike CP M ZCPR3 saves not only the drive but also the user number in the default file control blocks at 5CH and 6CH A ZCPR3 program need only fetch the values from the appropri
85. e to use everyting that I can get The industrial market has already developed architectures such as the VMEbus Motorola and Multibus InteD which provide most of the features required to use the full power of the new CPUs and 68020 80286 80386 and WE32XXX single board computers are readily available Simple low power systems can be used with a simple low power bus or even without a bus but high power systems must be used with a high power bus in order to realize their ful potentials and to provide for expan sion only be interested in using the new CPUs on a standard open bus ex cept possibly for a dedicated single use application such as a CAD station While we re talking about the new CPU s it appears that the software developers have stopped their work on the AT 80286 in favor of the 80386 Without the software to make use of the 286 s features the AT will just be used as a fast PC instead of realizing its full poten tial Why Companies Don t Succeed Most companies want to have their products considered for new designs and they spend a lot of money for slick four The Computer Journal Issue 27 color ads but then when we try to get technical information they fall flat on their face An example is the AD639 Trig Processor chip from Analog Devices I wrote three letters asking for tech info to publish but never received a response In November I finally phoned and taiked to someone in marke
86. earrange the information to get the desired results I made one mistake during this process which sent the machine into the operating system but I had saved each screen to disk and only had to reboot to make corrections and try again The first word you can use is HELP which gives you an introductory set of Screens to the program This introduc tion gives you some of F83 s words both in the tutor program and regular F83 The means the end of a series of screens and will drop the program back into F83 as indicated by the prom pt REPT will repeat the series of screens again while will start the next set of screens Eliminating the line 0 and some extra returns enabled the next screen s text to display immediately after the first after you hit a space bar ESC will terminate the displaying of screens but GET will start where you left off PRTSCR will tell you what each of the two variables contains the screen pointers GET amp REPT To enter text you use the built in F83 editor and start each screen with 0 NEW This will allow you to enter text one line after the other while editing previous lines will require you looking up the commands until you get used to them Now that I am getting used to the commands I have found the editor to be OK especially when you consider it is available at all times I am planning on writing the tutor screens along the lines of Leo Brodies Sta
87. ecifies the start address on 4K byte boundaries for Common Area 1 THIS ALSO DETERMINES THE LAST ADDRESS OF THE BANK AREA After a hardware reset ail of the CA bits are set to 1 BAO bits 3 0 BA specifies the start address on 4K byte boundaries for the Bank Area THIS ALSO DETERMINES THE LAST ADDRESS OF THE COMMON AREA 0 After a hardware reset all of the BA bits are set to 0 Let s actually set up the CBAR register for the following memory map which is the same map as used in the RAM disk drive that I will show later in this article MEMORY Logical Address FFFFH 32K 8000H 7FFFH 32K 0000H The Computer Journal Issue 27 SCSI ENGINES Little Board 186 495 High Performance Low Cost PC DOS Engine Boots IBM PC DOS e pe 7 not included ao bee To x am 7 Three times the COMPUTING POWER of aPC Data and File Compatible with 18M PC runs MS DOS programs 8 MHz 80186 CPU DMA Counter Timers 128 512K RAM zero wait states 16 128K EPROM Mini Micro Floppy Controller 1 4 Drives Singie Doubie Density 1 9 sided 40 80 track 2 RS939C Serial Ports 50 38 400 baud 1 Centronics Printer Port 5 75 x 7 75 inches mounts directly to a 5 1 4 disk drive Power Requirement 5VDC at 1 25A 19 0 at 05A On board 12V Converter SCSI PLUS multi master I O expansion ous Software Included PC DOS compatible R
88. else x d else it dx gt 0 d else 1 d t incr do pixel x y color move x2 y2 end of draw C Column continued Graphics References This has been a rapid introduction to graphics For those who wish to delve a little deeper into the subject or want to try their hand at developing their own routines here are some references you will find helpful Bruce A Artwick 1984 Applied Concepts in Microcom puter Graphics Prentice Hall Inc Englewood Cliffs J D Foley and A Van Dam 1982 Fundamentals of In teractive Computer Graphics Addison Wesley Publishing Company Reading Steve Harrington 1983 Computer Graphics A Program ming Approach McGraw Hill Book Company New York William M Newman and Robert F Sproull 1979 Prin ciples of Interactive Computer Graphics McGraw Hill Book Company New York That s it for this time The next column will finish up the primitive package and we can move on to some interesting ap plications 8i je t f examp 15 to open PI Surplus Parts Resource Here s a catalog any serious computer tinkerer needs It s a treasure trove of stepper motors gear motors bearings gears power supplies lab items parts and pieces of mechanical and electrical assemblies science doo dads goofy things plus project boxes lamps fights switches computer furni ture and stuff you might have never real
89. em The DOS sees the storage device in terms of allocation blocks which we will refer to only as blocks from here on It knows only how many blocks the disk will hold The concepts of sectors and tracks it leaves to the BIOS to figure out The total number of blocks available on the disk allows a of the disk in allocation blocks to be built If the disk is a small one of less than 257 blocks the map for the entire disk may be referenced in a single byte If the disk is a large one we will have to use a word or two bytes to map the disk To avoid ambiguity in map making a two byte map should hold a predefined set of numbers The size of the allocation block therefore directly effects the production of a map of the disk The disk capacity and the block size determine how many block numbers will fit in the data map of the disk If we make the number of blocks less than 256 a single byte then the block size must be large a single directory entry can command more disk space and we will waste more disk space because of the large The Computer Journal 18846 27 block size The block size and disk capacity determine the amount of space which can be described by a single directory entry This amount of disk space controlled by a directory entry is called a data map The amount of space controlled by each entry in the data map will be either eight or sixteen times the size of an allocation block This i
90. ent which reads in an assembly language COM file during compilation The assembly routine must be relocatable only relative jumps and its length must be included in the first two byte and this is all spelled out in the manual It also in cludes type and version checking across compilation units and can be used for large program development and for operating system concepts like con currency and interrupt handling I feel that while a lot of work is still being done in BASIC it should be replaced by Turbo Pascal for trivial programs I also feel that Turbo Pascal should be replaced by C or Trubo Modula 2 plus assembler for non trivial programs I didn t find anything about producing ROMable code in the Turbo Modula 2 manual so BDS C may have an advantage there TCJ intends to support both BDS C and Turbo Modula 2 and is especially in terested in acquiring extended library modules to be published in the magazine and posted on the BBS Send us infor The Computer Journal Issue 27 2 FREE CATALOG AND SOFTWARE APPLICATIONS GUIDE i XFER 5 7295 CP M M soos SOFTWARE ANALYSIS CIRCUIT DESIGN GRAPHICS MATHEMATICS 57255 57295 AFFORDABLE ENGINEERING TRSDOS PCDOS TEKCALC e 4Uentfo TTL ator a cs MATRIX 17295 6 i0 57295 FON 57255 57295
91. es The Computer Journal Issue 27 and comments he will have to come up with the instruction and argument fields for each line This means he must already have the program Since even a rudimentary disassembler has trouble producing the processor instruc tions for a program you will have to come up with a disassembler that knows how to combine your label names and comments with the disassembled structions This is not a trivial task but its not that difficult either What you up with is a program that reconstruct the source code on the customer s computer system In this way you would only be distributing your label names and com ments along with simplistic disaassembler that knows how to put the pieces back together again And impor tantly the author is not cheated out of any royalties that are due because the user must already have a copy of the program Which hopefully was obtained properly The results of this fancy foot work is that the customer has to wait a short while for the source code generator to produce the final files The generator for TURBO Pascal takes about twenty minutes to produce 21 000 lines of assem bly code Not a big inconvenience con sidering the immensity of this task These knowledgable highly specialized disassemblers are what I call Source Code Generators C C Software has these available for CP M 2 2 45 CP M 3 75 and TURBO Pascal v 3 CP M Z 80
92. es like MP M OASIS and MS DOS to absurd ones like ED and LOTUS 123 Who even uses ED and who has enough disk space to hold LOTUS The Process of Generating Usable Source Code Prior to disassembling a program you want to learn as much about how it works as you can You need to know exactly what the program does and have a reasonable idea of how it does it When you understand what a program does on a gross level you will be able to understand the finer details when you get to them When I start on a disassembly project I find it is generally a Six step process 1 Understand what the program does and how it functions 2 Determine the begin end and initial execution addresses 3 Identify the instruction and data areas 4 Isolate the subroutines and identify the lowest level ones 5 Comment and label the subroutines 6 Comment and label the main program code Before you can effectively use a disassembler you will have to know the bounds of the program you are dealing with I generally use DDT to get a rough idea of the end address This will display the address of the physical end of the executable file The actual end of the program is somewhere before this The Computer Journal Issue 27 Depending on the type of program it may or may not be easy to locate an effective ending address At the very least you can use the physical end address until experience indicates otherwise With most disassemblers especially M
93. esults 1111 through for skew table display number of entries set counter get dph address save 11 get last position update and save It get byte zero d value In a largest value start of table what position none of those see where In table first position of 20 see If need zeros hi has vatue print decimal value get count see If done yes return Insert comma Insert space see If done fil remainder count down and save ZERFIL LO POSIT 0 2 LO POSIT A LO A 0 CALL COUT LD A POSIT 0 RET 2 LO A CALL COUT CALL COSPAC JP ZERF IL 2 convert binary hl to ascii DECOUT LD B 0 LD DE 100 CALL SUBTR 10 DE 10 CALL SUBTR 10 A L ADD 0 JP COUT subtract powers of 10 wee 9 9e SUBTR LD C 0 1 SUBT2 INC ADD HL DE JP C SUBT2 b one to many add one back LD A D CPL LD D A LD CPL LD E A INC DE ADD HL DE LD check for zero we we we how many zero s done if zero count down and save we we print 0 see If through now we print print space decimal leading zero fill hundreds tens ascii bias print and return to caller we we ascii count add neg number complement de 9 get count CP 3 less than 1 JP no LD A B check O flag OR A LD A C restore RET 2 3 skip leading zero JP COUT 3 print char
94. example the TURBO Pascal manual uses FIB while describing file interface blocks Maintain these same naming conventions TURBO Pascal is a good example as the manual goes into considerable detail on the structure of some internal data areas like the file interface blocks and the storage of real and integer type numbers Plus a memory usage map is provided Very handy There are three very gross sections to all programs These are 1 the initialization section 2 the main working sec tion and 3 the wrap up section Initialization There are certain similarities among most programs when it comes to initialization One of the first things a program is going to do is setup a machine stack area This is because CP M does not define how much stack space is already available To be safe programs will generally set their own space aside for this It is easy to spot You are going to find a LD SP nnnn or similar type instruction very early in the initialization phase Secondly the memory limits will have to be established For programs that want to use all available memory there will something similar to LD HL 0006 followed by LD nnnn HL This is because CP M maintains a jump instruction to the BDOS at location 5 and this is the lowest location used by CP M Everything below this is available for the program to use On occasions you will find a program that does not use too much memory and then it merely saves the return address by POP HL and L
95. f the chip serve to make the design and production of a system easier and cheaper for the manufac turer and will be transparent to the applications level programmer However if you are a systems level programmer or desire to use any of the memory above 64k in any ap plications then you will need to become familiar with the methods used to control the various on chip functions In addition to the on chip ports used to control the additional integrated hardware there is an extended instruction set Many of the new instructions are directly related to on chip port I O and will be of no real use other than to avoid I O address conflic ts between the on chip and external ports or to make sure that the high order bits of the address bus are all 0 if ANYTHING is on the high 8 bits of the address bus the Hitachi s ports won t be accessed There are several new instructions that will be of use to any assembly level programmer They are MLT multiply two 8 bit values with 16 bit result TSTIO AND the contents of a specified I O port with the accumulator TST g AND specified register and accumulator TST m AND immediate data and accumulator TST HL AND memory and accumulator All of the TST instructions are non destructive on the ac cumulator eliminating the need to save and or reload the ac The Computer Journal Issue 27 cumulator after the AND operation The fiags are set reset in the PSW a
96. ferent path as before and stay much closer to the origin The plot of Figure 7 shows that the compensated loop is stable for loop gain of 500 and unstable for a loop gain of 4000 Printing the LOCIPRO data in a tabular format it is easy to see that a complex pair of poles migrate into the right half plane at a loop gain of 3286 At a loop gain of 2000 the poles are located at 33 235i Therefore the loop should be stable at a gain of 2000 This much gain should provide the desired accuracy Having the roots near the imaginary axis predicts a fast response We only have to see if the transient response meets the 0 1 second set tling time requirement We use the LOCIPRO program to save the closed loop tran sfer function for the compensated loop and then use the Signal Processing Program SPP to compute the step response The time domain waveform we wish to compute the response for is generated within SPP or some other program Although any user defined waveshape could have been used in this case a rec tangular waveform was selected The closed loop transfer fun ction file created by LOCIPRO is read into SPP and the time domain response computed SPP performs this operation in 35 seconds by using Fast Fourier Transform FFT techniques SPP takes the rectangular wave and performs a 512 point FFT on the signal to determine the constituent frequencies and the magnitude and phase of each of these frequencies The resulting freque
97. for Dissection Before setting cut to produce source code for that super new program you first want to know if you can succeed Before I embark on a new project I ask myself these questions Is there a real use for the source code for this program Is the program small enough that I can complete this project in a reasonable amount of time Was the program written in assembly or at least compiled with a good non threaded compiler Disclaimer The guidelines contained herein are for educational pur poses only The legality of disassembling a program is not totally free from doubt although it is done on a routine basis Software licenses may impose limitiations that the user should be aware of It is certainly not the intent of this article to deprive any software producers of rightfully earned revenues The Computer Journal Issue 27 Is the program static or does it move itself around in memory The answer to these questions when taken together help me to decide whether or not to try to disassemble a program I really try to avoid programs that move themselves in memory like DDT does I know of no disassembler which can handle these types of programs successfully The program size is also very important I have found that on the average every processor instruction uses 2 bytes of memory if it is 8080 code and 1 5 bytes if it is well written 2 80 code this includes most normal data areas This means that an
98. fter each lesson you are given the Forth prompt and can enter any F83 word try new words run samples from the lesson or Jeave F83 by going BYE I found using Forth to be easy and simple I use many different systems and CPUS which started me on Forth and will be the only language I could use on all the units Currently I have to learn everything all over again when ever I change systems while learning Forth would allow me to learn only one system F83 contains most functions you might consider when developing a program or changing a system and as such could be the solution to efficiently using many systems Giveitatry W Editor Continued from page 3 make the minor revisions so that a program does what we want it to do My first choice is a program which includes the source and my second choice is a program which I can figure out how to patch Clark Calkins method of disassem bling programs in order to provide modifiable source code is very important for those of us who are working with CP M programs which are not supported because of the manufacturer s neglect or the fact that they are out of business and we are very thankful that Clark is taking the time to share his knowledge with us in this first article of a series I would like to see source code generators for popular but undocumented CBIOSs disk format programs boot PROMS etc If you have a likely candidate and would be willing to coope
99. gains A gain of about 2000 would be desirable and thus it will be necessary to compensate the loop to improve the stability margin The design of loop compensators in general is a topic worthy of an article in itself We cannot do such a topic justice in a few words and we will not try to do so here Let it suffice that many loop compensators are just lead lag networks which improve phase margin for the loop by delaying the point at which the poles move into the right half plane A lead lag compensator for the loop described by Figure 4 was designed to stabilize the loop This loop compensator having a transfer function C s 0 15 1 S is added to the loop giving us the block diagram shown in Figure 6 13E 5 572 444 3 5 1 Figure 6 Compensated Loop Block Diagram 16 The data for the feedback system described by the transfer functions of Figure 6 are now entered into the LOCIPRO program and plotted using the Plotter Driver Program PDP The results shown in Figure 7 lt gt c c m 200 212 Real Axis Figure 7 Root Locus of Compensated System Note that the plot of Figure 7 is made on a different scale as that of Figure 5 The loop compensator has the poles closer to the origin The additional zero at 10 0i results in a drastically different starting point for the closed loop poles As the gain K is increased the poles migrate over a dif
100. gment deals with all hardware requests in a sentence type format It does not however have much knowledge about what the system hardware looks like The BIOS Basic Input Output System is the only segment which deals directly with the system hardware Because the other segments of the CP M system require no hardware specific information CP M may be run on nearly any manufacturer s hardware This is the purpose of the CP M concept and why we don t have compatibility problems the way the 16 bit systems do Less than a fifth of a standard BIOS is concerned with tasks not associated with disk management When we begin to think of disk management we are concerned with the entire BIOS and cannot simply isolate a given segment and work with it Far too many concepts or small details are interrelated and these small details form the dominate four fifths of the BIOS Getting Started From here on we will refer to a generic operating system as the DOS which is assumed to be ZRDOS CP M Hermit DOS or any other CP M derived operating system The DOS can manage nearly any type of disk storage device we care to connect to the system These devices may range from a single density 5 inch drive to a quad density or for the little AMPRO 80 megabytes of hard drive storage Wait just a minute Didn t he just say the DOS segment has little knowledge of the disk hardware Yes I did There isn t really a conflict of concep
101. h that the processor may not be fast enough to lay down records as fast as the destination spot spins under the heads of the drive By spacing the sectors the processor access win dow is made larger The access window is designed to eliminate an additional revolution of the disk for a missed sec tor In hard disk systems skew is called the interleave factor The DOS can determine if skew is used by calling the BIOS function SELDSK select disk which returns the address of the DISK PARAMETER HEADER We will refer to the disk parameter header as DPH from here on DOS will check the fir st word of the DPH to see if it is a zero value If the value is zero then no skew is used and the record position calculated from the record number represents the actual record position on the disk If the first word of the DPH is not a zero value it will be the ad dress of the skew table in the BIOS The algorithms which deal with the skew factor are often as unique as the results of the other trade off decisions made by the author of the BIOS If the disk uses skew the DOS will call the BIOS function SECTRAN to translate the logical record position into the physical record position This table is required to manage the skew factor of an alien disk and that it is data we must have to read or write an alien format We now at least know something of the parameters con tained in the DPB and have a basic understanding of the data we must provide
102. hanged Trick Code You may find that assembly programmers love to use cer tain 5 that improve execution speed or save memory You have to watch out for this or you could get really confused TURBO Pascal in many places uses instruction sequences like ReadFile LD A OAFH ORG 5 1 WriteFile XOR A AND A PUSH AF By jumping into the middle of the instruction at the program is able to set a flag byte using register A that is zero on a write and non zero on a read This saves a few bytes and drives the disassembler crazy Change these into something like ReadFile D8 Wr iteFile XOR A AND A PUSH And add some good comments so you will know what is going on the next time you have to look at this One way of logging an error message where it is desired to load register A with a value say from 1 to 5 to correspond to error code could be done as follows Errors INC A Error4 INC A Errors INC A Error2 INC A Error INC A 10 ErrorCode A To log an error then the following sequence would work this saves a single byte for each occurrence XOR A CALL Error4 12 Initially when you disassemble this type of code sequence you may be tempted to think that the series of INC A instruc tions are really data After all it doesn t make much sense at fir st But as you uncover those locations where these instructions are referenced you soon discover what is going on an
103. hat many users get confused and make mistakes Suppose you want to be clever and helpful by displaying a directory of existing programs to jog the user s memory before asking for his choice You might think of using the script S dir z80 setfile 1 Enter program name This will not have the effect intended One must not forget that the user is prompted for input by the shell at the time the script is expanded not at the time when the command line is executed In this example the user will be prompted for his choice before the directory is displayed Thus the directory display is useless To achieve the result intended above you must combine scripts You can create an ARUNZ alias called SETNAME with the following script ARUNZ supports prompted input SETNAME setfile 1 Enter name of file The MENU script would then be S dir 280 arunz setname When the MENU script is expanded the command becomes DIR 280 ARUNZ SETNAME and this command is then run It is not until ARUNZ SETNAME is executed that ARUNZ prompts the user for the name of the file At this point the direc tory of files with type Z80 has already been displayed on the screen There is obviously much more that could be said about the command line generators in ZCPR3 The discussion here has been only an overview but I hope that it will inspire you to take a fresh look at and to experiment with aliases and shells of all kinds the standalone aliases generated
104. he number of blocks a disk will hold This figure represents the capacity of the disk When all the blocks are assigned to a directory entry the disk is full end of story Right from the start I am going to run afoul of CP M pun dits The parameter I refer to as Records per Track is generally called Sectors per Track What it refers to is the number of 128 byte data segments per track Sectors have not been 128 bytes per track since the 8080 processor was new So The Computer Journal Issue 427 Little Board 249 The World s Least Expensive CP M Engine CP M 2 2 INCLUDED Ne 3 system with ZCPR3 Read write format dozens of floppy formats IBM PC DOS KAYPRO OSBORNE MORROW 4 MHZ ZBOA CPU RAM 280 4 39K EPROM Mini Micro Floppy Controller 1 4 Drives Single Double Density 1 2 sided 40 80 track Menu oased system customization e 285030 Serial Ports 75 9600 baud OPerator friendly MENU shell amp 75 38 400 baud 1 Centronics OPTIONS Printer Port Source Code Power Requirement 5VOC at 75A 9 19VDC at 05 On board 12V 25005 Hard disk expansion to 60 converter megabytes Only 5 75 2 inches mounts e SCSI PLUS multi ter O directly to a 5 1 4 disk drive nsion bus Comprehensive Software included Enhanced CP M 2 2 operating Local Area Network STD Bus
105. heir CPU car ds All their I O and memory will most likely work without any changes This type of upgrading is hard to beat Where I work we have many industrial con trollers all with different software and hardware To maintain or program these systems requires sending the personnel to a factory school always on the other side of the USA and then being locked in to their price and service STD bus products are available in many con figurations with some local dealer or manufacturer support available Because the basic CPU can be the same for all uses only learning one system is needed for programming or maintaining When it comes to really special uses where you must build your own with STD you only build that part which can t be found elsewhere The reason I like STD bus over others is cost they re Continued on page 51 The Computer Journal issue 27 Back Issues Available _ jue Number 1 RS 232 Interface Part One Telecomputing with the Apple II Beginner s Column Getting Started Build an Epram meN umber 2 File Transfer Programs for CP M RS 232 Interface Part Two Build Hardware Print Spooler Part 1 Review of Floppy Disk Formats Sending Morse Code with an Apple II Beginner s Column Basic Concepts and Formulas sue Number 3 Add an 8087 Math Chip to Your Dual cocessor Board Build an A D Converter for the Apple Modems for Micros The CP M Operating System Build Hardware
106. ically shifted to the right in a 16 bit register to obtain its allocation block num ber The size of the allocation block may be determined by initializing a 16 bit register with 128 and shifting this value LEFT the number of times in the BSH byte The BSH is followed by the BLOCK MASK byte which con tains a value which if logically ANDed with a record number will produce the RELATIVE NUMBER of the record within its allocation block The EXTENT MASK field of the DPB shows the relationship between the physical and the logical extent The logical extent is derived from dividing the record number by 128 The physical 42 extent may also be determined from the extent mask but it is generally easier to get the record number shift it right BSH times and then divide the result by eight or sixteen depending upon the number of blocks in the data map The DSM or DISK BLOCK MAXIMUM word reveals the highest possible allocation block number available for the disk of concern Remember that in computers the number zero is the first num ber and a valid number Hence the number of allocation blocks or the highest allocation block number is one more than the value in the DSM The size of the disk may be computed by initializing a 16 bit register with the value of the DSM 1 and double that value BSH 3 times The number of records may be determined by doubling the result BSH times If you are slick as the byte count will overflow a 16 bit register
107. icrocom puter This is being built from Steve Ciarcia s book Build Your Own 7 80 Computer Byte Books 1981 You should have this in your offerings it is of great interest to some if not many of your readers The circuit he uses was the winner in a competition of four different possibilities What was needed was a single board controller computer It is to serve as a data logger and whatever else comes to mind For several years I have been trying to find a public domain com puter sufficient for a beginning student to wire wrap and use for some significant purpose There are simpler solutions to the problem such as the 8748 single chip microcomputer However this 2 80 board has some extreme advantages First all of the software will be upward compatible the next step up might be a Little Board Second all lines off the CPU are buffered with the expectation of adding odd ball devices to the exterior Third there are two 8 bit parallel ports input and an 8 bit output port with an optional RS 232 serial port To make the projects initially useful it will be an en Continued on page 50 BUILDING A ROBOT MOTION PACKAGE DIRECT GEAR DRIVE FOR WHEELS 12 INCH OR LARGER INCLUDES 2in DC MOTORS 2ta 16 1 GEARBOXES 200 24 TOOTH STEEL SPUR GEARS 20 60 TOOTH NYLON IDLE GEARS 258 235 TOOTH 121NCH DRIVE GEARS MOTOR GEARBOX amp DLE GEAR ARE PRE ASSEMBLED DRIVE GEAR IS READY TO MOUNT ON YOUR WHEEL
108. in front of the command and enter a wildcard file name that specifies the file you want That s all there is to it have W implemen The Computer Journal Issue 827 ted in an alias on my Z Node system so that users can type a file without having to enter the exact name If a user can t remem ber or doesn t really care whether the file is AUTOINST FIX AUTOINST FQZ or AUTOINST FZX all he has to enter is AUTO and the file whatever it is called will ap pear on the screen Command Line Generators Many people call me about problems they are having get ting an alias or VFILER script to work correctly Often the problem turns out to be a misunderstanding of what command line generators are really doing I will try to shed a little more light on that subject here First a little philosophy There are many features in the Z System about which one might well at first just shrug one s shoulders and say 50 what The flow control system discussed earlier is one such feature and multiple commands on a line might be another After all how many of us actually think far enough ahead to enter more than one command at a time anyway Well the answer lies in the interplay of all the features in Z System and in the ways they allow things to be ac complished automatically Aliases The multiple command capability of Z System for example is important not so much because it allows the user to enter a whole
109. ing the in formation discovered in graf Resetting the video mode will automatically set the page to 0 so if a video page other than the first was being used it has to be set independently 18 Where Do We Go From Here Now that we know how to start and stop what do we do while we re there Let s start with the function for setting a pixel do pixel O This particular routine is very straight forward being a single call to int86 The parameters passed are the x y coordinate of the pixel and the color you wish it to be 4defines for valid colors are given in graph h Listing 1 Equally simple is the move function which updates the value of cur x and cur y to the x and y coordinates passed to it Note that both the move function and the draw function I ll be talking about in a minute are absolute routines That is the x y value passed is a screen coordinate not an offset These functions can be augmented by relative ones which do use an offset very easily Using the move function as an example it would be void move rel xoff yoff int yoff int x y x cur_x xoff y cur_y move x y A function draw rel would be identical except calling draw instead of move discuss draw and clip at the same time since clip is used by draw to clip lines to the screen The draw function uses the Bresenham line algorithm to draw a line from the current x y location
110. ir cards CPU and memory except the special I O they need I attended one of their sales seminars on the STD unit also a factory school on the big system and was given not only a demonstration of how the system worked but all their source code for the special math routines they use They feel that if you are going to properly use the product or maintain it you must have all the code they use When asked about who supplies the cards which they don t make they gladly tell you where to get them Their attitude is that they sell a complete service of large machines and controllers and your satisfaction with their entire line is more important than a few lines of code they wrote On the other side of the coin is a product which I personally was able to buy recently The same friends who sold me my portable also had a GIMIX system they got at auction which was gathering more dust than use I removed this unit from their warehouse and have been trying to use it ever since What really got me was the factory response when I called them for information Now their literature says they do not make any consumer products only industrial use is warranted but if my use had been industrial I certainly would not use them What happened was nothing they stated they destroyed all information on older products and would not sell me anything to help me bring the unit up When I asked what I should do they said to use it for parts I was able to u
111. is especially useful for setting up menus for your spouse or co workers to use the computer as they never have to see the A prompt All they have to do is press a single key to run any single or muitiple CP M programs and when the task is done control is automatically returned to the menu ordinary CP M menu programs cannot do this Extended Command Processing When you type a command under CP M it will oniy look for the program in the current drive and user area ZCPR3 gives you more flexibility by additionally searching other disks and user areas when resolving commands You have full control of this function called the PATH This is probably the one element of ZCPR3 that is missed most if you return to ordinary CP M Also ZCPR3 supports the capability of grouping all your commonly used utility programs into a library file LBR This is great for systems with a small number of directory entries per disk as the library file only uses one entry It also has the advantage of reducing disk space requirements for a given set of programs allowing you to put more programs on a disk And the programs in the library file are invokable from the command line just like any other program not in the library Echelon Inc Other Features There s much more to ZCPR3 like named directories online help system etc but it can t be described on one page If you would like more information consider the books shown below Z SYSTEM
112. is program is END described in the AMPRO technical manual Continued on page 51 Subscriptions U S Canada Surface Total Foreign 6 issues per year New Renewal lyear 16 00 2years 28 00 Back Issues Six or more S Total Enclosed All funds must be in U S dollars on a U S bank O Check enclosed VISA O MasterCard Card Expirationdate Signature Name Address City tate ZIP The Computer Journal 190 Sullivan Crossroad Columbia Falls MT 59912 Phone 406 257 9119 Leere ee eg Ge omme meem es ees ee ee ee ee eee oe Orders can also be entered by modem on the TCJ BBS 406 752 1038 by leaving a private message for SYSOP with the required information The Computer Journal 18846 27 49 Feedback Continued from page 35 vironmental monitor All data will be collected as frequencies counts so the sixteen bits will provide a convenient in put mode This is primarily because my moisture detector the most difficult is a frequency dependent device Then resistance light and events will just be counted and entered as numbers also to be decoded by software Yes software I have none Some modifications have been made to the board to make it more transportable to other beginners The memory is now a 6116 2K X8 RAM which exactly matches a 2716 EPROM a
113. it From the Wordstar like editor to the error correction process I find that with Turbo I can do in four hours what would have taken two days using conven tional systems The why is the objective approach of the system I currently feel that the computer in dustry is running amuck with all the new found speed and options Programs and hardware too are being pushed to their limits in many cases just to find those limits Now I have little complaint about finding out just how far you can push things I did that when I first learned how to drive After finding myself in a ditch one night I learned when to push and when not to The industry hasn t learned when not to push and I feel this is due to sell sell and more sell The competion is fierce and only getting worse Anybody who really says I liked it when will be considered old fashioned or not with it by most computer users Nice ideas but what really are we trying to do I feel the objective is to get the job done in the most cost effective and time efficent manner Computers can do that but only if used properly I think Art and others like him are heading in the right direction by using combinations of existing products to achieve their goals One area that I have been pushing for some time is the use of the STD bus for industrial control Any company that started using STD bus with Z80 or 6809 CPUs can now upgrade to 8088 or 68000 by only changing t
114. itially look for CP M BDOS references These are call or jump instructions to location 0005 The process to access CP M is well defined The function number is loaded into register C and any parameters use register pair DE You might have to look a few instructions ahead of the BDOS call or jump to find where register C is loaded Then refer to the CP M Reference manual for the meaning of this function Keep a chart on the wall with a summary of these functions You will refer to it of ten By using this approach you can identify the file routines open close read write delete rename etc and the console routines character input character output status etc It should not take too long to disassemble and comment the lowest two levels of subroutines You should then have labeled subroutines like CreateFile PrintChar WriteFile ConsoleStatus etc These will be the work horse of the program as all other subroutines will need to use these There will come a time when you seem to be unable to progress with this bottoms up approach Maybe by the third or fourth level of subroutines At this time you need to call upon your knowledge of what the program does and start a top down approach You will need as much information as you can get on how it functions For example if you are disassembling an editor like the editor portion of TURBO Pascal you know that this will read the keyboard determine if the key or keys
115. ized you needed All at deep discounts cause they are surplus Published every couple of months and consecutive issues are completely different Send 1 00 for next three issues JERRYCO INC 601 Linden Place Evanston Illinois 60202 hine he e s 0110 The Computer Journal Issue 27 The Hitachi HD64180 New Life for 8 bit Systems by Jon Schneider This article was written with the intent of giving those un familiar with Hitachi s new 8 bit microprocessor an understan ding of its advantages over the Zilog Z 80 Also through the use of some actual 64180 bios level code an understanding of how to utilize some of its advanced features The Hitachi 64180 is a highly integrated 8 bit CMOS based micro processor designed to be fully compatible with the large base of Z 80 software already in existence In addition to an enhanced instruction set and increased throughput the chip performs many of the functions that previously required a large number of support chips A few of those functions are Onchip MMU supporting up to 512 bytes of linear address space Two channel DMA Programmable RAM refresh rates Programmable memory and I O wait states Two fully programmable 16 bit reload timers Two full duplex asynchronous serial ports One clocked serial I O port Interrupt controller can use reload timers to generate in terrupts Ability to relocate on chip I O addresses Many of the features o
116. l Issue 27 best you can and put the remainder off until later As you disassemble the rest of the code you will find out under what circumstances this subroutine gets executed This may give you the insight you need to understand it 4 Termination Like the initialization section the termination portion of a program is fairly standard The program has to clean up and then get back to CP M somehow The process of cleaning up may be trivial for some programs Others may have to flush buffers and close data files Some times the stack pointer is reset to the value it had when the program was first executed This seems to be common even though it is not required by CP M If buffered data output is used then the program must be sure the buffers are flushed written to the disk prior to closing the files There are two common procedures to flush buffers The first is to have a separate subroutine that writes the current buffer as it is This is the cleanest method but takes some extra memory The other process is to write enough end of file marks as to be sure to overflow the buffer which causes it to be written If the buffer holds 1024 bytes then if that many EOF s are written to the buf fer you know that it must have been written I do not consider this as clean as the first approach as it could result in an extra buffer being written but it generally takes less memory to im plement Stumbling Blocks By the very nature
117. l Low tmdrih equ 15h PRT Timer Data Reg Chn 1 High ridrii equ 16h PRT Timer Reload Reg Chnl 1 Low ridrih equ 17h PRT Timer Reload Reg Chnl High DMA Controller DMAC sarol equ 20h DMAC Source Address Reg Chn 0 Low sarOh equ 218 Source Address Reg Chnl 0 High sarOb equ 22h DMAC Source Address Reg Chn 0 Bank equ 23h Dest Address Reg Chnl 0 Low darOh equ 24h DMAC Dest Address Reg Chn 0 High darOb equ 25h DMAC Dest Address Reg Chn 0 Bank ber Ol equ 26h DMAC Byte Count Reg Chnl 0 Low bcrOh 27h DMAC Byte Count Reg Chnl O High mar equ 28h DMAC Memory Address Reg Chni 1 Low marih equ 29h DMAC Memory Address Reg Chnl 1 High marib equ 2ah DMAC Memory Address Reg Chn 1 Bank iari equ 2bh DMAC 1 0 Address Reg 1 Low iarlh equ 2ch DMAC 1 0 Address Reg Chnl 1 High ber 1 equ 2eh DMAC Byte Count Reg Chni 1 Low berih equ 2fh Byte Count Reg Chn 1 High dstat equ 30h DMAC Status Reg dmode equ 31h DMAC Mode Reg dent equ 32h DMAC Control Reg Interrupt Control Registers il equ 33h INTERRUPT Vector Low Reg itc equ 34h INT TRAP Control Reg Refresh Control Register rer equ 36h REFRESH Control Reg Memory Management Unit MMU cbr equ 58h MMU Common Base Reg bbr equ 39h MMU Bank Base Reg cbar equ 3ah MMU Common Bank Area Reg 1 0 Control Register ier equ 3fh 1 0 Control Reg The Computer Journal Issue 27
118. l issue 27 Listing 2 Memory drive read routine Input Select parameters in Select Control Block Output Record moved to DSBDMA mdread cp 02h Is it a write jr z mdwrit Jump if so call mdaddr Else set up addresses jr mdmove And read the record Memory drive write routine Output Record moved from DSBOMA mdwrit cali mdaddr ex de hl Set up addresses Switch for write Memory drive data move routine 3 Input A Address select bits for move HL Source address for move DE Destination address for move Output 128 bytes moved as requested mdmove di No interrupts outo bbr a Switch in bank call movrec Move the record xor a O bank O outo bbr a Switch in norma map ei ret Memory drive address setup routine Input Information in Select Block Output A Map address select bits DEsInternal record buffer address HL Record address in alternate Memory Map eys we we we mdaddr push hi Save buffer address id Sector toL 14 h 128 Multiply by 128 mit hl HL now contains address in bank 14 Track to Multiply by 8 ric a ric a mdadrt add a bank Add BBR offset pop de DMA addr to DE ret The Hitachi 64180 holds great promise for the 8 bit world and for CP M in particular If half of the products promised for the chip are delivered then you you will find 64180 based systems will be around for a long time If you are i
119. l of the shell in the former case In the latter case the shell actually carries out its real function in life Let s consider the MENU shell as an example When the MENU COM is loaded as a shell it displays a screen of command choices to the user Each single character choice is associated with a command line script much like the alias script When the user strikes a key MENU looks up the script associated with that character expands the script sub stituting parameters and puts the resulting command into the multiple command line buffer It then returns control to the ZC PR3 command processor ZCPR3 executes the commands in the command buffer one after another until they have all been per formed Then when the command buffer is empty again ZC PR3 looks in the shell stack finds the MENU command there and runs MENU again This process continues until a special user key is entered control c in the case of MENU that signals the shell that it should remove itself from the shell stack Then things return to the state they were in before the shell was in voked initially by the user Shells by the way can be nested the usual shell stack is four entries deep so when one shell removes itself from the shell stack control may still not return to the user Another shell whose role was superceded by the most recent shell may now come back into control With the MENU COM the displayed menu of choices and the Scripts associated with the
120. l port is addressed the PROM is shifted into high memory This is taken care of in the boot PROM so all the user will see is RAM memory at location 0 The BIOS is in PROM so it is assumed to run at 380000 All interrupts are auto vectored some are dedicated to devices on the board and some are available on the expansion connector P1 CONNECTOR EXPANSION 1 04 55 05 2 03 34 06 3 02 35 D7 4 DI 36 D8 5 00 37 D9 6 AS 38 010 7 1065 39 DII 8 LOS 40 012 9 R W 4 015 10 DTACK 42 014 11 808 45 015 12 BGACK 44 GND 13 BR 45 A23 14 VCC 5 V 46 22 15 CLK 8 MHZ 47 A21 16 GND 48 VCC 5V 17 HALT 49 A20 18 RESET 50 19 19 VMA 51 18 20 E 52 A17 21 VPA 53 16 22 BERR 54 15 23 IPL2 55 14 24 IPLI 56 A13 25 IPLO 57 A12 26 FC2 58 All 27 FCI 59 AIO 28 FCO 60 A9 29 Al 61 A8 30 A2 62 A7 31 A3 65 32 A4 64 A5 EX101 DREQ EXIRI EXIRS EXIR6 GND 16 MHZ CLOCK NC NC 052 053 052 051 SIDE SEL NC SERIAL CONNECTOR NC GND NC NC NC RIAL CONNECTOR NC GND NC RTS ON BOARD P2 CONNECTOR EXPANSION 1 EXIO2 9 2 12 10 3 12 11 4 YCC 5 12 5 VCC 13 6 SND 14 7 GND 15 8 GND 16 P3 CONNECTOR DISK 1 SND 25 3 GND 4 5 GND 6 7 GNO 8 9 GND 10 11 GND 12 13
121. ld operate both correctly and automatically I have now written a new FCP package FCP10 that is presen tly under test by ZSIG program committee members and should be ready for release with the next ZSIG diskette It handles both resident and transient code It can examine the command line to see if there was a colon before the IF In that case the FCP ignores its internal condition options and invokes the transient IF COM immediately If no colon was present the FCP first looks to see if the condition option is included in the resident code If not it automatically invokes the transient IF processor The user need not be concerned with which options are resident inthe FCP The script IF NULL 1 inan alias will take advan tage of fast resident processing if the NULL option is supported in the resident code or will automatically invoke transient processing if not When one wants to be sure to get transient processing one simply uses the colon as in IF EXIST FILEL FILE2 To go along with FCP10 there is a new transient IF processor COMIF10 It supports dozens of additional condition tests One is AMBIG which tests a file specification for am biguity question marks or asterisks Register numeric and string alphabetic comparisons are now extended to the full range of tests equal not equal greater less greater than or equal and less than or equal I plan to add file attribute testing SYS DIR RO RW ARC WP and testing for the
122. led in a standard location near the beginning of all true Z System programs Next DO COM takes its command script appends any other commands in the multiple command line that come after the command and then writes the result back to the command line buffer When it then returns to Z System the ZCPR3 command processor as usual looks at the command line buffer to see if there are more jobs listed there for it to do Since DO COM has filled the command line buffer with the script ZCPR3 responds just as if we had typed the long command line script instead of The Computer Journal Issue 27 SAGE MICROSYSTEMS EAST Selling amp Supporting The Best In 8 Bit Software Plu Perfect Systems Backgrounder II switch between two or three running tasks under CP M 75 DateStamper stamp your CP M files with creation modification and access times 49 Echelon Z System Software ZCOM automatically installing full Z System 70 basic package or 119 with all utilities on disk ZROOS enhanced disk operating system automatic disk logging and backup 59 50 050 the incredible Oynamic Screen Debugger lets you really see programs run 130 SLA Systems The Ultimate Assembiy Language Tools Assemblers 280 5 280 SLR180 HD64180 SLRMAC 8080 and SLRO85 8085 Linker SLRNK Memory based versions 50 Virtual memory versions 195 NightOwi Advanced Telecommunications MEX P
123. lest we have over 2000 in stock 4 mhz Z80A CPU 64K RAM 16 32K ROM 2 RS232 serial ports 300 19 2k baud with db25 con nectors instalied Centronics printer port 22016 se Power requirements 12vdc 12vdc 5vdc Floppy disk controller up to 4 drives SSDD standard Rom for DSDD 48tpi or 96tpi 12 extra including assembied bios CP M bios Wordstar and Bazic included Schematic bios asm maint manual and users guide included Copy program to read write non morrow formats such as Kaypro Osborne Xerox amp etc 9 Optional 523 torr inal pcb monit or isplay We 59 with purchase Cpu savings fro pr 5 C PL or ae 1 90 fer Pri C pense orice a ffer AJ i supelies lest res or credit ZWuititech KEYBOARDS SITAS FOR AT 84 KEYS KBOB4 395 97 KEYS 97 5490 FLOPPY CONTROLLER WITH LPT1 PRINTER PORT FOR IBM OR CLONES TANDEM PCBA188400 ONLY 24 15 DAY TRIAL PERIOD HURRY SUPPLY WONT LAST LONG AT THIS PRICE VE A NEW BBS PLEASE GIVE I 2 AT 415 261 4513 AND LET ctr d BRIAN friest e extra Sende check or edd 3 1 mE sone ies riw Eng 28 i H mm mE 4401 OAKLAND 9460 1542 TBI Reader s Laser Rangefinder I am a student in a Science amp Technology program and during our Senior year we m
124. lt dos h gt C Column 27 Listing 2 include f include include cur x cur y set current x y location minimum values tor x and maximum y value maximum x value x min y min 349 039 current x coordinates max and min screen values video page and mode at startup int cur x cur y int x max x min y max y min int page mode 128 enss jeuuJnor sandwon eu static union REGS inreg outreg defines for foreground colors define define define unions for 10 86 BLACK BLUE GREEN inteygeh ah UxUf int86 UxlU page outreg h bh mode outreg h al inreg h ah 0 iureg h al 0 10 int86 UxlU amp inreg amp outreg get current display mode RUM video call 1011 3 monitor page to reset Lo monitor mode to reset to set EGA high res mode 640 x 350 define CYAN end of graf init def ine RED def ine MAGENTA define BROWN define WHITE define GREY define LBLUE define LGREEN define LCYAN define PINK vvoid graf term define LMAGENTA def ine YELLOW define BWHITE graf_term reset the system reset the system to the way it was before the initialization call description inreg h ah U reset the mode inreg h al mode intB6 U0xlU amp inreg amp outreg void graf init
125. lus automated modem operation 60 Terminal Emulators VT100 TVI925 06100 30 Same day shipping of most products with modem download and support available Shipping and handling 4 per order Specify format Check VISA or MasterCard Sage Microsystems East 1435 Centre St Newton MA 02159 Voice 617 965 3552 9 00 a m 11 15 p m Modem 617 965 7259 24 hr 300 1200 2400 bps password DDT on PC Pursuit the simple DO Now let s see how flow control can be used with alias scripts One problem with the command sequence in our example arises when the assembler reports an error In that case there is no sense going through the MLOAD operation Assemblers like ZAS from Echelon and Z80ASM from SLR Systems set a flag in the Z System to show whether or not they encountered any fatal errors during the assembly and the flow control command ERROR can test the state of that flag We can improve our script as follows EDIT 280 ZAS MYPROG IF ERROR MLOAD MYPROG FI In this script the MLOAD command will only be executed if the program error flag has not been set by ZAS the tilde has the meaning not Typing all those flow control commands manually would be more trouble than entering single comman ds at a time but with an alias we are still typing only two let ters DO So far so good But what happens when we want to start work on another program say NEWPROG Do we have to creat
126. mable Key PKey 39 95 1 disk 43 Special hems 40 through 42 89 95 3 disks 60 DISCAT Disk cataloging system 39 99 1 disk 61 TERM3 Communications System 99 00 6 disks 64 Z Msg Message Handling System 99 00 1 disk 81 ZCPR3 The Manual bound 350 pages 19 95 82 ZCPR3 The Libraries 310 pages 29 95 83 Z NEWS Newsietter 1 yr subscipton 24 00 84 2CPR3 and IOPs 50 pages 9 95 85 ZRDOS Programmers s Manual 35 pages 8 95 88 Z System User s Guide 80 page tutorial 14 95 includes ZCPR3 The Manual ITEM PRICE Subtotal Sales Tax Shipping Handling Total The Computer Journal Issue 27 ZSIG Corner Command Line Generators and Aliases by Jay Sage ZSIG Software Librarian When first offered to write a regular column for The Computer Journal I wondered if I would have enough material for a column every two months Instead the problem has become one of finding the time to set down all the thoughts I have For this issue I had planned to cover four topics there is only room for three of them They are 1 corrections of some errors in the last column and an excuse for more discussion of flow control in 2 System 2 a brief rundown on the files in the first officially released ZSIG diskette and 3 a discussion of command line building programs in ZCPR3 including aliases and shells Corrections There were two errors that I noticed in the last column One was a minor one that was Art Carlson
127. may assume only a limited number of sizes to remain compatible with the DOS Of these limited values at least one is considered obsolete All possible values are related to other disk parameters The size of the allocation block simply expressed for now is the amount of disk space used in all transactions A better way of putting it is that if a two Character file shows up in the directory as using 2K of disk space then you may assume your system uses a 2K allocation block size The size of the allocation block is a great headache for the format designer File space is allocated only in terms of blocks In the two character file example there is a large waste of disk space We can expect that at least half of the last block in a given file will be wasted This waste factor is what prompted the LU COM and NULU COM library utilities to be created they free up much of this wasted space within the individual files Now then it seems logical that the larger the allocation block the greater the amount of space which will be wasted This is a valid assumption The considerations are the size of the disk being used and the number of files likely to be placed upon it It would follow that the lower the disk capacity and the greater the number of files to be placed upon the disk the smaller the allocation block should be It is not that simple even if we knew for certain what kinds of drives those darned TCJ readers would attempt to connect to our syst
128. meters for restoration 128 9 0114 Column 27 Listing 2 it x2 lt x min code used by Cohen Sutherland clipping algorithm ud y2 dy x min description prov des the four bit code needed to determine where 2 x min the line segment falls in relation to a viewport a 2 gt x max int code x y 2 dy x_max int x y x2 return x lt x_min lt lt 3_ x2x max 442 lt lt lt 1 2 max y2 y min end of code 29i x2 dx y min clip clips a line y2 y min description clips a line to a viewport using the Cohen Sutherland 2 gt max algorithm T x2 dx y max y2 y max int clip xl yl x2 y2 int xl yl x2 y2 void move move x1l y1 int code end of clip int cl code xl yl int c2 code x2 y2 moove performs move int dx dy description performs a move does not draw and resets the values f A while cl I c2 3 or cur x and cur y i if cl amp c2 void move x y return int x y dx x2 xl dy y2 yl cur x x if cl cur y end of move if xl x min yl dy x draw draws a line using the Bresenham algorithm x description draws a line from the current location to the location xl gt x max referenced by x2 y2 It also updates cur x and cur y yl 7 dy
129. mined by how three of the 64180 s internal registers are set up The first register that needs to be set up is the CBAR register Common Bank Area Register It determines which of the three logical partitions will be used and where they will be located within the 64k of logical address space SEVERAL POSSIBLE CONFIGURATIONS OF MEMORY AS DEFINED BY CBAR As you can see in Figure 1 the starting and ending ad dresses for the three segments WITHIN the 64k logical address space have all been set although I didn t show the actual ad dresses and whether or not a particular segment will even be used is also determined Common Area 0 if used MUST always start at logical and physical address 0000 The Bank Area must start at either the end of Common Area 0 if it was used or at logical address 0 Common Area 1 must start at the end of the Bank Area if used or the end of Common Area 0 if it was used and the Bank Area was not used or at address 0 Both the Bank Area and Common Area 1 serve as areas for the actual switching of physical memory into the logical address space All of the areas must start on a 4k physical address boun dary Now that you have an understanding of what the 3 segments are lets see how the CBAR register determines the actual location of the segments MMU Common Bank Area Register 1 0 Address bit 7 6 5 4 3 2 1 0 CAS CA2 BAS 2 BAI CA3 CAO bits 7 4 CA sp
130. n Z 80 Zilog MT BASIC Softaid Inc Turbo Pascal Borland International Where these terms and others are used in The Computer Journal they are acknowledged to be the property of the respective companies even if not specifically mentioned in each occuren ce 68000 TinyGiant Low Cost 16 bit SBC and Operating System by Art Carlson There has been a lot of interest in a low priced 680009 single board computer for experimenting or process control and a group of us got together at SOG last year to discuss the situation We are interested in the 68000 because it is big fast cheap and well supported The 86 family is dominated by MS DOS PC DOS machines which are designed as office machines and the other 32 bit micro processors are not very well supported We wanted to work with a processor for which books are available and we also wanted other companies to provide software for the new machine The major problem in experimenting with the 68000 has been the lack of a readily available low cost operating system and programming utilities As a result of our discussions Joe Bartel Hawthorne Technology offered to supply a single user version of his 68000 operating system complete with the source code and the compiler for his HTPL language in which the system is written for 50 He s even throwing in a line editor and a 68000 assembler Once we had the operating system we started searching for suitable hardware since n
131. n go to drive We can only access 32MB of our present 40MB drive now leaving a lot of unused area I guess the problem comes down to the formatting program for the hard disk which limits us to four apparent drives currently E F G H We are using an Adaptec ACB4000 so have a second SCSI slot available to run another drive What appears to be needed are the following 1 Modifications to HDINIT COM allowing us to set up say five drives per 40MB hard disk of say a little under 8MB each 2 A way to be able to configure another drive as drives J K L M etc which doesn t appear possible at present Our present hard disk is a NEC D5146 Possibly since it has only 4 data disks item 1 is impossible but I see no reason that item 2 can not be done Unfortunately our programming is done in the higher level languages such as Dbase Pascal etc and the hieroglyphics of HD64180 and Z 80 assembly code are Greek to us I guess we shall have to take the bull by the hor ns one day and get down to it Thanks for an excellent publication to date Keep it up and please ensure no defection to the Imbecile s Biggest Mistake J T L Editor s Note As I understand it the basic problem is that CP M can only ad dress 8MB per drive and the hard drive controller can only handle four drives Thus you can only partition a physical drive into four logical drives of 8MB each and four times eight equals thirty two The answer i
132. ncy components are called the signals spec tra The resulting complex spectra is then filtered through the transfer function one frequency at a time The transfer fun ction modifies each frequency component of the original time domain waveform The resulting frequency spectra is then con verted back into the time domain by performing an inverse FFT The spectra multiplication technique in the frequency domain is identical to convolution in the time domain where the The Computer Journal Issue 827 rectangular input signal is convolved with the impulse response of the closed loop transfer function Spectra multiplication is far faster than convolution and it takes SPP only 35 seconds to perform all three operations FFT Filter IFFT The results of the transient analysis of the compensated system is shown in Figure 8 compensated Transient Resoonse 4 m cot a 4 4 a c Output Signal Figure 8 Transient Response of Stable Platform A book with Table of Contents Optimization Techniques Using the DOS Background Print Spooler System Level Tools Creating Libraries Exploiting Command Line Arguments Using a Binary Search Tree Techniques for Data Compression Claiming CP M Memory Break the 64K Data Limit Linked Lists for Data Structuring Interrupts from Turbo Pascal Cailing the DOS Command Processor Bit Mapped Graphics Teaching an Old Screen New Tricks Implementi
133. ndered What Makes CP M Tick Source Code Generators by C C Software can The S C G programs produce fully commented and labeled source code for your CP M system To modify the system to your just edit and assemble with ASM CP M 75 1 50 postage in Calif add 6 53 C C Software 1907 Alvarado Ave Walnut Creek CA 94596 415 939 8153 CP M is a registered trademark of Digital Research Inc At the same time as the current products are being sold in volume there are also a lot of technical developments taking place which will affect what we buy in the near future but these developments are not taking place in the consumer market which everyone is watching but rather in the industrial market where they are not attracting much attention There is a lot of talk about how much power the Motorola 68020 68030 and 68040 and the Intel 80286 and 80386 will provide but there is very little talk about what kind of system architecture will be needed in order to realize these benefits It s true that MicroSoft and others are developing operating systems for the 80386 but apparently the hardware people remember that they are used to dealing with buyers spending some one else s money are talking about putting it on a glorified PC type bus That s like putting a turbo charged V 12 engine in a old Ford model T I feel that the advanced business engineering and industrial systems which can properly utilize the po
134. ng 2D Core Graphics Build a Subset Pascal Compiler 900000000000 The Computer Journal issue 27 packed with good advanced technical information The platform output closely tracks the desired input and set tles to a steady state rate within the required 0 1 seconds With a loop gain of 2000 this tight loop should track the commanded rate quit closely The gain margin for the loop is 20 Log 3286 2000 4 3 dB not high but acceptable under most con ditions This concludes the discussion of root locus techniques and the example using the LOCIPRO program Several books which are good reading should you desire a more in depth knowlege of root locus techniques are listed below References Dorf R C 1967 Modern Control Systems Addison Wesley Cannon R H Jr 1967 Dynamics of Pkysical Systems McGraw Hill Melsa J L and Jones S K 1973 Computer Programs for Computational Assistance in the Study of Linear Control Theory McGraw Hill 8 ADVANCED TOPICS in TURBO PASCAL Turbo Pascal Advanced Applications Order Turbo Pascal Advanced Applications tor 19 95 post paid in USA with MS DOS disk 32 95 Add 3 50 for surface ship ment to Canada or other countries air rates on request Order from Rockland Publishing inc 190 Sullivan Suite 103 Columbia Falls MT 59912 Visa or Mastercard accepted Phone orders call 406 257 9119 Free information is av
135. ningful label names or comments But have patience you will be learning a lot more as time goes on Main Program Body This is the heart of any program and the section which is dif ferent for every one Luckily programs are generally written in a modular fashion Sections of code perform a specific task This makes it easier for the programmer to write and later debug it And happily it makes it easier to disassemble TURBO Pascal had three main portions that were disassembled separately run time library editor and compiler By locating the logical divisions of a program you can minimize the cross com munication which hinders the disassembly process When you first start on the main program section keep in mind that a program is a collection of subroutines tied together in a particular order As you browse through the code initially try to get an idea of the programming style Items to keep track of are Are subroutines generally kept in one location like the beginning or end of the program s there a constant pattern of calling subroutines certain registers always used for arguments Do routines always terminate in a return instruction Or do they use jumps to other routines to save time Are certain registers sacred and not used by subroutines Dosubroutines always preserve registers To answer these questions examine the first few subroutines you find These are easy to spot Just check the destination of
136. nterested in more information on the XLR8er 64180 based enhancement for the TRS 80 Model 4 contact H I Tech Inc P O Box 25404 Houston TX 77265 1 800 835 2246 ext 202 or contact my BBS system Rio Grande Z Node 39 915 592 4976 B 27 n WHO WE ARE Echelon is a unique company oriented exclusively toward your CP M compatible computer Echelon offers top quality software at extremely low prices our customers are overwhelmed at the amount of software they receive when buying our products For example the Z Com product comes with approximately 80 utility programs and our TERM ill communications package runs to a full megabyte of files This is real value for your software dollar ZCPR3 Echelon is famous for our operating systems products ZCPR3 our CP M enhancement was written by a software professional who wanted to add features normally found in minicomputer and maintrame operating Systems to his home computer He succeeded wonderfully and ZCPR3 has become the environment of choice for power CP M users Multiple Commands per Line You can easily use multiple commands per line under ZCPR3 Simply separate the individual commands with semicolons For example PIP 5 B will copy files and then show you the STAT results User Programmed menu systems ZCPR3 comes with three different menu Systems that you can use to create custom menu driven front ends for your computer This
137. ointers arrays and local variables Trace and set breakpoints using procedure names of sourca Statements View source code while debugging 2 Use Turbo Pascal editor and DOS DEBUG tommands TOebugPLUS includes a special MAP file generation mode fully compatible with external debuggers such as Periscope Atron Symdeb and others even on programs written with Turbo EXTENDER An expanded supported version of the acclaimed public domain program TDEBUG the TDebugPLUS package includes one DSDD disk complete source Code a reference card and an 80 page printed manual 256K of memory required Simplify debugging 60 COMPLETE TURBO EXTENDER Turbo EXTENDER provides you the following powerful tools to break the 64K barrier a Large Code Model allows programs to use all 640K without overlays or chaining while allowing you to convert existing programs with minimal effort makes EXE files Make Facility offers separate compilation eliminating the need for you to recompile unchanged modules a Large Data Arrays automatically manages data arrays up to 30 megabytes as well as any arrays in expanded memory EMS Additional Turbo EXTENDER tools include Overlay Analyst Disk Cache Pascal Encryplor Shell File Generator and File Browser The Turbo EXTENDER package includes two DSDD disks complete source coge and a 150 page printed manual Order now 85 COMPLETE TURBOPOWER UTILITIES
138. on The function graf_init does this setting the current x and y location the maximum and minimum x and y coordinate values getting the display mode parameters operative when the graphics application started and then setting the system into high resolution graphics mode I must admit I ve cheated a bit on this function since I ve hard wired the initialization routine for an Enhanced Graphics Adapter EGA For those not using an IBM or compatible system this card provides higher resolution and more colors in both the foreground and background than the Color Graphics Adapter a palette of 16 64 It would be possible to write an initialization routine that could check whether the system had a CGA or EGA video card but there are differences between the cards that go beyond resolution that would complicate some of the other routines Ialso don t have a CGA card to test the code I would write The int86 function accesses the DOS interrupts and is used here to access interrupt 10H ROM BIOS video interrupt Users of non IBM systems will have to find the appropriate means to do the analogous on their machines The first cail finds out what the video mode and video page are when the application starts so that the same environment can be restored on exit The second call sets the video card into the EGA high resolution 640 x 350 mode Once the application is complete the function graf_term restores the original video mode and video page us
139. ore wasted space we have on the disk Another consideration about the size of the allocation block is the relationship to the number of directory entries it takes to describe the entire disk We must consider two extremes of disk space management On the one hand we must consider that someone may place all his files in a library and the entire disk may be filled with only one file A single directory entry therefore must be capable of describing the entire disk if it has to If the directory were constructed any smaller than that which could command the entire disk space it would not be possible to use the entire disk On the other hand the disk may be filled with two character files commanding a single block There must be enough directory entries to handle the load From what we already know the smaller the block size the more directory entries would be required to describe the entire disk Just to make things interesting let s establish the rule that there cannot be more than 16 allocation blocks used by the direc tory Yes you had better dust off that old calculator and send out for another bottle of you favorite headache reliever The basic rule of thumb here is that the smaller the block size the larger the directory must be It would also be logical to think that the size of the disk wouid play a major role in determining the allocation block size since it affects so many small con siderations The DOS requires the BIOS to tell it t
140. ot all of us are interested in designing and wirewrapping the main CPU board I understand that some people are porting Hawthorne s K OS ONE operating system over to the Atari ST which is a great hardware bargain but we also need a small low cost board which can be mounted on robotic arms and other places where an ST is too big or is technically unsuitable After all for many controller ap plications we don t need sound graphics drives keyboard or monitor but we do need complete bus access so that we can provide lots of 1 Joe came up with another winner which is the 68000 single board computer he calls TinyGiant Every computer is designed to fill a particular goal or market niche and The TinyGiant was designed to be as low cost as possible while still providing the needed features The target price was set at 395 and when a choice had to be made they looked at the original goal Then they looked at what was needed to make a usable small developement system There had to be a disk of some kind There also had to be enough I O to support a terminal and some kind of printer and a modem They didn t put a video controller on the board because they felt that many of these would be used in places where video was not needed Also video would have made the board much larger and more costly Dynamic RAMs were used because of the lower cost The TinyGiant is a complete 68000 system on a single board The main component
141. rate in a group effort we can t expect Clark to do all this work for us drop me a note or post a message on our BBS If there is enough interest we ll organize a SIG While talking about source code note that Hawthorne s 68000 operating system includes the source code plus the com pilier for the language in which it is writ ten 8 bit Developments There is still a lot of activity in the 8 bit domain with 2 80 and HD64180 single board computers selling well There are also a lot of 8 bitters still in use and they are ideal tools for learning about inter facing and how operating systems work Toshiba and Zilog should both know how many 8 bit chips are being sold and they have just announced new Z 80 family devices which means that they plan on producing a lot more of them Toshiba has introduced a line of Ap plication Specific Standard Parts ASSPs which include a CMOS Z 80 CPU with peripheral functions on one chip Their 784 which combines the Z 80 with a clock generator controller a counter timer and five 8 bit parallel 1 0 ports comes in a 100 pin flat pack in 6 or 8 MHz with 10 MHz promised The I O por ts are bit enabled and each port bit can be used as input or output The 784 013 is designed for dedicated communications with serial I O and the Z84CO15AT designed for com munications with parallel I O Zilog has announced their Z84C80 CMOS chip which can replace 70 to 100 SSI MSI chips in a Z
142. ress ail editorial and adver tising inquiries to The Computer Journal 190 Sullivan Crossroad Columbia Falls MT 59912 phone 406 257 9119 The Computer Journal Issue 27 the COMPUTER JOURNAL Features 68000 TinyGiant Hawthorne s 68000 Single Board Computer combined with their 50 operating system by Art Carlson The Art of Source Code Generation Disassembling 2 80 software to produce modifiable source code by Clark A Calkins Oa tad eek Feedback Control System Analysis Using Root Locus analysis and Feedback Loop Compensation to solve closed loop control problems by Bert P van den The Hitachi HD64180 Understanding the HD64180 s advantages over the Z 80 and how to use some of it s advanced features by Jon A Tutor Program for Forth Writing a Forth Tutor in Forth by Bill Disk Parameters Modifying the CPIM Disk Parameter Block to read and write foreign disk formats by C Thomas Departments Editorial C Corner by Donald 2510 Corner Reader s Feedback Computer Corner 4 as 8 23 DRE
143. rnational High perfor mance with many advanced features includes editor compiler linker 552 page manual and more Z COM 5 disks 119 00 Easy auto installation complete Z System for virtually any 280 includes 80 utility programs and ZCPR3 The Manual Z Tools 4 disks 150 00 A bundle of software tools individually priced at 260 total Includes the ZAS Macro Assembler ZDM debuggers REVAS4 disassembler and ITOZ ZTOI source code converters HD64180 support PUBLIC ZRDOS 1 disk 59 50 If you have acquired ZCPR3 for your ZBO compatible system and want to upgrade to full Z System all you need is ZRDOS ZRDOS features elimination of after disk change public directories faster execution than CP M archive status for easy backup and more DSD 1 disk 129 95 The premier debugger for your 8080 280 or HD64180 systems Full screen with windaws for RAM code listing registers and stack We feature ZCPR3 versions this professional debugger Quick Task 3 disks 249 00 Z80 HD64180 muititasking realtime executive for embedded com puter applications Full source code no run time fees site license for development Comparable to systems from 2000 to 40 000 Request our free Q T Demonstration Program Z System OEM inquiries invited Visa Mastercard accepted 4 00 shipping handling in North a
144. rside CA 92501 USA ond m 714 781 0252 They even have an on line bulletin board to list some of their latest bargains See their ads in this issue for some great deals including the Morrow Micro Decision mother board which makes a great single board computer Forth Fan Don t let us down I still wish there were some Forth articles in TCJ but I ll be content as long as you continue to sup port CP M as well as MS DOS I know I m not alone when I say that having a MS DOS machine hasn t made me want to trash my CP M box es G S Editor s Note We haven t turned down any Forth articles we just haven t received many See Kibler s TUTOR ar ticle in this issue and tell potential Forth authorstocontactus g 39 Disk Parameters Modifying the CP M Disk Parameter Block for Foreign Formats by C Thomas Hilton A number of our readers have asked for more information on tailoring the CP M BIOS and specifically on how to modify the BIOS in order to read other disk formats Information on writing to the disk is very hardware specific but there are some generalities and the information on the AMPRO Little Board will serve as a starting place for those with other systems We must keep in mind the basic structure of CP M or CP M derived operating systems The CCP interfaces with the human operator and relies upon the FDOS Floppy Disk Operating System segment for all hardware interface The FDOS se
145. rting Forth but felt the idea of getting tutor programs out there more important than the text itself Conclusion In using other tutor programs I have found them both difficult to use and im possible to fit my needs I found most users either know too little or too much to make proper use of the program s infor 37 The 51 words are important utilities in F83 and may be differen from previous versions WORDS will display a list of 7 amp 3 words used OPEN allows use of an existing file EXTEND is usec to add screens and CREATE is used for making a new file INOL displays a list of line O use 1 20 INDEX to list screens to 20 1 30 SHOW will print 6 screens to a page on your printer in condensed mode use EPSON IS INIT PR for epson printers 1 30 TRIAD prints three to a page if condensed print is not available 1 30 SHADOW SHOW will print both the SCR 4n TUTOR BLK THIRD PRINT SCREEN OF TUTOR INFORMATION bdk120186 regular screens on the left side and the information screen on the rignt side of each page SEE xxxx disassembles the word xxxx while VIEW will open the source file on A drive and list the screen it is in VOCS will list the vocabularies in the dictionary while ORDER displays the path of the directory search Use DOS WORDS to see a list of the DOS dictionary words CAPACITY will print the number of screens in a open file AL wil toggle between the shadow and the source screens N L will
146. ructions that do allow some flexibility in this regard but this is not always enough If you ever wanted to learn how to write an operating system or compiler and only had a book or two for reference you would then see the advantage of having some source code to refer to This is indispensable Can the source code for any program be produced Theoretically the answer is yes However from a practical standpoint only a few programs would be worth the effort in volved The idea to keep in mind is that if the computer can execute the program it can be disassembled This is because the process of disassembling a program is really a conversion from one language machine code to another Like translating a book from German to English except there are no ambiguities to worry about Documenting the program now involves just time and effort maybe quite a lot of these The specific type of source code generation I am going to be dealing with here is the creation of Z 80 assembly source code If it were desired to create Pascal or Fortran source code assuming the program was written in one of these languages the first step would be to produce assembly instructions and convert groups of instructions into source statements This would require a thorough understanding of the code produced by the compiler A difficult task indeed but it can be done In addition I will be assuming that CP M is the operating system being used and that it is desired
147. s e Soldering and Other Strange Tales Build a 5 100 Floppy Disk Controller WD2797 Controller for CP M 68K The Computer Corner lane Number 21 e Exten urbo Pascal Customize with Procedures and Functions Unsoldering The Arcane Art Analog Data and Control Connecting Your Computer to the Real World Programming the 8035 SBC The Computer Corner Issue Number 22 NEW DOS Write Your Own Operating System e Variability in the BDS C Standard Library The SCSI Interface Introductory Column Using Turbo Pascal ISAM Files The AMPRO Little Board Column The Computer Corner Issue Number 23 Column Flow Control amp Program Structure The Z Column Getting Started with Directories amp User Areas car SCSI Interface Introduction to NEW DOS The Console Command Processor Editing The CP M Operating System INDEXER Turbo Pascal Program to Create Index The AMPRO Little Board Column The Computer Corner Issue Number 24 Selecting and Building a System The SCSI Interface SCSI Command Protocol Introduction to Assembly Code for CP M The C Column Software Text Filters AMPRO 186 Column Installing MS DOS Software The Z Column e NEW DOS The CCP Internal Com mands ZTIME 1 A Realtime Clock for the AMPRO Z 80 Little Board Issue Number 25 Repairing amp Modifying Printed Circuits Z Com vs Hacker Version of Z Sys
148. s Printer Port 128K RAM expandable to 512K on board Expansion Bus 5 75 x 8 0 Inches Mounts to Side of Drive Software Included 5 05 ONE the 68000 Operating 5v 2A 12 for RS 232 System source code included Power Connector same as Command Processor w source disk drive Data and File Compatible with MS DOS Add a terminal disk drive A 68000 Assembler and power and you will have An HTPL Compiler a powerful 68000 system A Line Editor 395 00 x 13 x 05 ONE 68000 OPERATING SYSTEM For your existing 68000 hardware you can get the 05 ONE Operating System package for only 50 00 K OS ONE is a powerful pliable single user operating system with source code provided for operating system and command processor It allows you to read and write MS DOS format diskettes with your 68000 system The package also contains an Assembler an HTPL high level language Compiler a Line Editor and manual ASSEMBLED AND TESTED ONLY SHIPPED ON AN MS DOS 5 1 4 DISK 50 00 Order Now VISA HC HAWTHORNE TECHNOLOGY 503 254 2005 8836 S E Stark Portland Or 97216 The Computer Journal Issue 27 TURBO PROGRAMMERS CUTS DEBUGGING FRUSTRATION TDebugPtus is a new interactive symbolic de bugger that integrates with Turbo Pascal to let you a Examine and change variables runtime using symbolic names including records p
149. s a day for seven days a week I may add more 96TPI flop pies because the drives only run when they are accessed instead running all the time like a hard drive The real solution will be to go to battery backed RAM disk if and when I can justify the cost I would be very interested in feedback regarding other people s experience with the life of various models of hard drives Source Code I realize that you get tired of hearing me talk about source code but having the source code is what enables us to Continued on page 38 Make certain that TCJ follows you to your new address Send both old and new address along with your expiration number that appears on your mailing label to THE COMPUTER JOURNAL 190 Sullivan Crossroad Columbia Falls MT 59912 Please allow six weeks notice Thanks Registered Trademarks It is easy to get in the habit of using company trademarks as generic terms but these registered trademarks are the property of the respective com panies It is important to acknowledge these trademarks as their property to avoid their losing the rights and the term becoming public property The following frequently used marks are acknowledged and we apologize for any we have overlooked Apple II Macintosch DOS 3 3 ProDOS Apple Computer Company CP M DDT ASM STAT PIP Digital Research MBASIC Microsoft Wordstar MicroPro Inter national Corp IBM PC XT and AT IBM Corporatio
150. s a design rule This number is also represented by a term called a logical extent which will always be a multiple of 16 384 This is another design rule There is a case where these rules could be violated If the block size were 1K and the disk was so small that there were less than 256 blocks then a directory entry could command only 8K of disk space This is not a usable combination of disk parameters This combination is not allowed in modern design concepts The use of 1K allocation blocks may only be used with disks of less than 256K of data such as fruit loop computers and other low end consumer toys The block size also effects the relationship between the logical extent and the physical extent the actual amount of space commanded by a single directory entry The larger the physical extent the fewer the number of directory entries which will be required to describe a complete file The size of the physical extent is more than a theoretical design concept as it directly affects system performance It takes time to locate and open a new extent a seek of the disk head back to the direc tory track is required It follows that the larger the physical ex tent the less time would be required to process a large file The time it takes to find data on the disk is important when we begin to think about how the system will perform with random access files But as we have briefly discussed the larger the extent or block size the m
151. s to use more than one physical drive and more than one hard drive controller and partition each physical drive into several logical drives I also feel safer with my data spread over several physical drives I would choose 20MB drives each partitioned into four 5MB sections and would use ZCPR3 so that all user areas are available The Computer Journal Issue 27 Feedback Reader Feedback I am writing in response to your request for reader feedback I feel that TCJ is straying away from my needs A magazine that fullfills the goals as stated in the Editor s Page in Volume 1 Number 1 is exactly what I need Why not pick a project for exam ple your NC controlled milling machine project and carry it through to a useful end Where existing hardware is available at affordable hobbiest prices use it otherwise build it Where suitable software is available use it otherwise write it Don t turn the magazine into a generalized software magazine with too many articles like Affordable C Com pilers and Concurrent Multitasking For that kind of information I subscribe to Dr Dobbs Journal of Software Tools Don t turn into a computer industry news magazine with too many articles like Inside AMPRO Computers BYTE magaine s subscription gives me that While I enjoyed all the above articles I would rather have read them in magazines that I consider more ap propiate for them C D M Editor s Note Re
152. s would be expected for any other AND operation MLT will be covered in more detail later in this article The 64180 uses 64 I O addresses to control its internal ports and allows relocation of those addresses to any 64 byte boundary within the first 256 bytes of the 64k I O address space This was done to facilitate the add on of the Hitachi processor to existing hardware without causing I O address conflicts Due to the large number of internal ports I use an include file in all of my 64180 work and refer to the ports by their names as shown in the Hitachi manual This file is shown in Listing 1 and assumes that the ports start at address 0 The addition of a few new instructions would hardly qualify the Hitachi as a marked improvement over the venerable Z80 and other than than making the design of a new system easier it wouldn t be generating the interest that it is without something to make it much more powerful than the current 8 bit workhor se That feature is its ability to address up to 512k bytes of memory in a linear fashion Due to the lack of more than 16 bits of addressing for the programmer you are still limited to 64k of memory addressable at one time but developers can now code programs to utilize memory past 64k in a uniform manner much like PC DOS programmers now do If you are not familiar with how the IBM PC and other 8088 based computers address memory you may be surprised to discover that they have been working wi
153. se a third party to receive information and have since found out that these units are their current versions but with them destroying their documentation it is The Computer Journal 18846 27 rather hard to know what is really current I have several disk cards to sell as this unit was a disk drive tester with eight disk cards and must have cost someone over 9 000 in the beginning If I had been a manufacturer and spent nine grand for several systems only to have the manufacturer say I must buy a whole new system to fix my old one that would be the last time I did business with him Well that one call is the last time I will call GIMIX and they are not the only company I will refuse to do business with due to poor support or documentation Another big company which I will have little to do with is GE We have one of their big industrial controllers and it must be the most difficult unit to work on Becuse had had so much trouble figuring out their documentation and many other forms of troubles with them when it became time to upgrade an old lathe I got our managers to buy a older style Gidding and Lewis G amp L con troller The managers wanted to buy another GE controller because of the name until I explained all the trouble I had then they knew why they hadn t heard the G amp L name much before this the product caused little problems The GE was a mess and they lost 300 000 to G amp L You might say that was only one
154. ser or otherwise which should speak to the system hardware It would follow therefore that each BIOS is concerned only with the specific disk controller chip chosen by the hardware designer It is also proper to assume if you wished to physically format a disk in any style other than that specified by the author of the BIOS you will be required to write your own algorithms to deal with the hardware specific disk controller chip The AMPRO Emulator Disk Parameter Block Turning your attention to LISTING ONE you will see several DPB s such as we have been discussing Three of these segments describe the decisions made for disk format design by the original author of the AMPRO BIOS These decisions mark the characteristic AMPRO format from all other combinations of disk format design FIGURE TWO shows the standard con figurations of format design practice We have far to go in a short space I will leave the study of the various examples for your leisuretime Let us pay particular attention to the disk parameter block It may be located by the label Before con verted to AMPRO systems I owned a Kaypro 4 84 The disk in the example is set to the Kaypro 4 10 format by default I traded in the Kaypro for a Televideo terminal With most of my software library in the Kaypro format the default setting allows direct access to my software Just above the disk s DPB we will find a label entitled
155. t a different market and I believe that Hawthorne has made several very smart moves For one they re supplying the system with the board and the system whether obtained separately or with the board includes the OS source code plus the language compiler a 68000 assembler and a line editor so that you have the utilities to start writing programs Another very good move is that even though Hawthorne is selling a single board computer they still want to sell their operating system to hardware companies even if they are directly competing with Hawthorne Joe has also been in contact with a lot of potential 68000 programers who were frustrated with the lack of a low cost operating system and there will soon be a rapidly expanding base of software One of the most significant points is that you get the operating system with the source code plus the other goodies for only 50 Has any one else ever supplied the OS source code I doubt it because many CP M hardware vendors wouldn t even supply the source code for their customized CBIOS With the low cost OS and its source you can customize it for your own par ticular application and it s cheap enough so that you can in clude it with your software I feel that the use of K OS ONE is going to expand very rapidly and we at TCJ are going to fully support this growth 68000 Reference Book List 68000 16 32 bit Microprocessor Programmer s Reference Manual by Motorola Prentice Hal 68000
156. t have complex operating systems may leave less than 64K for your programs PCDOS running Framework and 384K mem Graphic systems are nice but if they are so com plex to program that you will not be able to write to them yourself why bother A solution for some user may be the same one have chosen Some time ago I started on a 68K FORTH operating system Hawthorne Technology has saved me from that task at present but I have become stronger in my feelings that seme form of a standard language and operating system is needed I can use four different CPUs 6809 280 8080 8088 68K and need some common way of going between them freely FORTH is currently the only option for me STD Bus users are also using FORTH because it is fast and can work in small memory systems If you re interested in FORTH look at past FORTH articles as well as my TUTOR program elsewhere in TCJ I think I will save some comments for next month so happy computing Disk Parameters Continued from page 49 Well we have more theory than ap plication in this article and because of the size of the listings and figures we had better bring this session to a halt I suggest you study the data given in this issue until the meaning of each byte of these parameters is understood fully It would not hurt to design a disk format of your own in practice to better under stand the decisions made by the designer of the AMPRO format The public domain DISK
157. t you or someone else schooled in the language can understand what is going on If you already have an executable program why would anyone want the source code The truth is many users would not But if you ever wanted to change a program source code makes it much easier In some cases it is not practical to change a program without the source Besides the necessity or desire to change a program some people would just like to un derstand how it works Why is it that software producers very seldom make source code available for their products There are several reasons or excuses for not releasing the source code These include 1 you don t need it program XYZ works perfectly as it is 2 could then make copies and give these to others 3 it s too complicated you couldn t understand it and so Actually the real reason is that software writers feel that their programs represent private and creative thoughts and that they loose privacy if the source code gets out of their control There is a mystique to writing programs and programmers tend to keep it that way A form of 100 security However users do have a legitimate requirement for source code After all the programmer wrote the program to do what he she thought was the best but the users generally have dif ferent ideas and frequently want to change the default values which were selected by the programmer Some programs come with installation inst
158. tem Exploring Single Linked Lists in C Adding Serial Port to Ampro Little Board Building a SCSI Adapter New DOS CCP Internal Commands Ampro 186 Networking with SuperDUO e ZSIG Column Issue Number 26 Bus Systems Selecting a System Bus Using the SB180 Real Time Clock _ The SCSI Interface Software for the SCSI Adapter Inside AMPRO Computers NEW DOS The CCP Commands Con tinued ZSIG Corner e Affordable C Compilers Concurrent Multitasking A Review of DoubleDOS The Computer Corner
159. the E disk support algorithms Fine but where do we get this information 43 12 ONSS jeuunof euL Figure Two Reasonable trade offs of disk format design parameters BLOCK SIZE BLOCK SHIFT LLELETEETETTTE 1024 2048 4096 8192 16384 O3H 04H 05H 06H 07H BLOCK MASK BLOCKS BLOCKS PER EXTENT PER DISK DATA MAP SIZE 256 16 16K 256 16 32K gt 255 8 16K lt 256 16 64K gt 255 8 32K lt 256 16 128K gt 255 8 64K 256 16 256K gt 255 8 128K LOGICAL EXTENTS ssszzzcz mIZz ILmzzzZzZzz2222224EZZEZZLLZLIZZLZELLILELEc 2z2zz2zzzzz222zazzzc EXTENT MASK OIH OOH 03H 07H NOTE A K BLOCK SIZE WITH MORE THAN 255 BLOCKS PER DISK IS AN ILLEGAL OPTION Zzzzzzzzzzzzzzlzzzzczzzlzzz2l22zzzzzczlzz2z2zzzzzzzlzzzzzzzzzlz22222rzzzz2zz2zzz2zzzzzzz Listing One AMPRO Standard and Emulator Disk Parameter Blocks DPBASE SPARM DPARM DPARM96 ORG DEFW DEFW DEFW DEFW DEFW DEFW DEFW DEFW DEFW DEFW DEFW DEFB DEFB DEFB DEFW DEFW DEFB DEFB DEFW DEFW DEFW DEFB DEFB DEFB DEFW DEFW DEFB DEFB DEFW DEFW DEFW BIOS 80H XLTO 0 0 0 DIRBUF CSVO AL VO XLTO 0 0 0 DIRBUF DPARM CSV1 ALV1 X
160. the LaPLace domain or as a function of the com plex variable s Next the roots to the denominator of equation 4 are determined as a function of loop gain When the roots are plotted in the s plane we can infer some characteristics about stability and transient response Roots which lie in the right half of the s plane correspond to an unstable system whose output to a step function input will oscillate with continually increasing amplitude Those roots lying in the left half plane with complex pairs will exhibit a response to a step input which may overshoot the step amplitude but will settle to the commanded step value The closer a com plex root lies to the imaginary axis the quicker the system response is expected to be That is the system will reach its final value quickly However the overshoot in reaching the final value may be substantial The converse is also true The closer a complex root lies to the real axis the slower its step response becomes The type of response for a system having roots located at various points in the s plane is shown graphically in Figure 2 We will now analyze a typical control loop compute the root locus of the system using the LOCIPRO 1 root locus program We will find that the loop is unstable This behavior will have been predicted from the system root locus by LOCIPRO A lead lag loop compensator is then added and the new locus of roots for the compensated system computed The new root locus pro
161. the call instructions You do not have to under stand the routines right off but make notes concerning any similarities that stand out If the program was written in a high level language there will be many and often wasteful similarities With these ideas in mind the next step is to identify as many of the individual subroutines as you can If you can insert com ments with the disassembler try to separate the routines with a blank comment line or two Some disassemblers do this automatically when they encounter a return instruction Most including MD do not 10 When beginning to disassemble a subroutine and comment it remember that subroutines are often nested subroutine A calls subroutine B which calls subroutine C etc You will find it easiest to locate the inner most subroutine the one that does not call any other subroutine within the program area that has not already been disassembled and begin there These are generally smaller with an easier to understand more direct purpose You will find that by documenting one of these low level routines and changing the references to it to a meaningful name like OpenFile you can go back to a parent subroutine and understand it a little easier Then go back to its parent subroutine and so on Because a subroutine is generally referen ced by many others documenting these small ones has a pyramid effect This bottoms up process is essential for even the smallest programs In
162. the case only in hard disk systems or where the medium is assumed to be nonremovable If the CKS value is not zero this word will be given a value representing the number of records in the disk s directory or DRM 1 4 Directory entries are packed four to a record The final entry in the DPB is the OFF word or RESERVED TRACKS OFFSET value of the concerned disk This word tells the DOS how many tracks are reserved for the operating system Knowing that some tracks are reserved the DOS will add this offset to the track number it computes using the record number and the RECORDS PER TRACK parameters of the DPB It may be interesting to note that the system tracks are always the first tracks on the disk hence the OFFset value poin ts to the first byte of the directory area on the disk The more enlightened reader may wonder at this juncture why this is a two byte field when only one or two tracks are normally reser ved for system use Well kind reader the DOS is prepared to handle 65K of reserved tracks this is true The reason this is done is to allow the use of hard disk systems If the medium is continuous of say 20 megabytes capacity and CP M allows a maximum of eight megabytes per disk how does one account for the palm sized AMPRO s ability to support 88 megabytes of disk storage You are correct if you feel the offset value is used to lie to the DOS segment On the 20 megabyte Little Board I use for writing it is not unusu
163. thin the same limitation of a 64k segmented architecture The main difference is that the 8088 based systems don t actually have to switch memory in and out of one 64k segment but have to use a segment register in ad dition to a 16 bit address to specify an absolute address You may have noticed that I mentioned 512k bytes of LINEAR address space for the Hitachi and then turned right around and said that the memory above 64k had to be switched in and out of the 64k address space the programmer uses That is not as contradictory as it may seem The address bus on the Hitachi is actually 19 bits wide allowing the processor direct linear access to any address within 512k bytes It is the programmer that has to work within the limits of addressing memory with only 16 bits Even that isn t entirely accurate as some operations such as DMA allow the programmer to specify the absolute addresses within the 512k byte address space Since addressing the 64180 s extra memory is one of the more confusing aspects of programming the chip I will cover it in detail The manual as supplied by Hitachi is somewhat con fusing and terse to say the least The 64k of memory that is accessible at any one time is divided into three separate areas called Common Area 0 Com mon Area 1 and the Bank Area How 512k bytes of physical memory is mapped into a logical 64K of address space is deter 23 FOR TRS 80 MODELS 1 3 4 4P IBM PC XT AT amp T 6300 ETC
164. ting who promised to send the info We still haven t received anything and frankly I m no longer in terested in dealing with them On the other hand I called Hitachi for info on their HD64180 and received a large box of material They also followed up with a phone call to see if I had received it and if I needed any further help Guess which product I ll support The American companies will continue to cry about how they are losing business to the foreign producers but in many cases it is their own fault because while they spend money on impressive advertising they won t pay attention to customers and provide support Hard Drives vs RAM Disks Hard drives are nice for operations in volving a lot of disk access such as data bases or compiling where the speed and capacity advantages over floppies are important BUT remember that when used continuously every hard drive will eventually FAIL The question is not IF but rather WHEN The expensive large drives intended for mainframe ap plications will probably last for a long time but some of the low cost drives for micros are not so durable In the case of the 10 Meg drive for our BBS the bearings gave out after about six months of continuous operation 1 noticed it in time to save the data but have to send the drive out for repair The board is running on just two flop pies until I decide on a long term solution but I question if I want a hard drive running 24 hour
165. to disassemble a normal transient program and not a ROM or other type of program Storage These are slightly more complicated as the execution address may differ from the physical address The disassembler I use is my own the Masterful Disassem bler or MD for short but most any quality disassembler can be used It is most handy if the disassembler allows label names to be associated with addresses and also supports comments lines All disassemblers I know of allow you to define which areas of memory are instructions and which are data the more data types supported the better You will find it particularly handy if the disassembler will recognize tables of addresses and put these into its label pool If the disassembler you use does not allow label names and comments to be entered then you will have to work from a prin ted listing and use an editor to keep track of things This is a lot more trouble on large disassemblies because up to date listings may take hours to generate and you will be tempted to try and get by with older ones This will sooner or later cause duplication of effort as you re comment some areas a second time For an example I will be referencing TURBO Pascal This is because I am familiar with it and it encompasses many features common to most assembly language programs There is a knack to disassembling programs After you have done one the next comes easier Just like programming Choosing the Proper Candidates
166. trol to the system All error information is retur ned in memory in the parameter block This makes it very easy to use system fuctions directly in a high level language The use The Computer Journal Issue 27 of Unix like files instead of file control blocks like CP M means that any application written will still run even if there are radical changes to the internal structure of the disks 68 TinyGiant Hardware Description There are 6 connectors on the TinyGiant board that connect it to the real world Two of these are for expansion one for the console serial port one for the auxillary serial port one for the printer and finally one for the disk drives The size and shape of the board is such that it can be bolted to the side of a standard 5 inch floppy disk drive and the power connector for the 5 and 12 is the same as used on a floppy disk drive The 12 volts is converted to 12 for RS 232 by an onboard power converter Most of the cheap PC clone power supplies already have the connectors wired for floppy disks so one of them can be used The expansion bus is divided between two connectors P1 and P2 The P1 connector brings out all the basic 68000 control signals These come directly from the 68000 cpu chip and are not buffered The remaining signals come from the P2 connector Any signal should be buffered before it is used on an expansion board When power is applied the PROM is at location 0 As soon as the seria
167. ts In beginning we will have to view the disk system as the DOS sees it and work our way deeper into the concept as we go Any other route in our quest would lead to miles upon miles of dull theory I would rather do than read wouldn t you Of all the thousands of details concerned with disk management only a few are of real concern to the DOS segment The DOS relies upon the BIOS to take care of these details The DOS asks the BIOS to provide it with a set of parameters describing the disk device Many times as we attempt to inter face new technologies with standard and aging systems all the better to upgrade them as we are doing here the BIOS will lie to the DOS segment about the disk drive What the DOS doesn t know won t hurt it The most common occurence of misinformation is about hard drives which were not common when CP M was written 40 Primary Disk Parameters Some Theory The DOS asks the BIOS for parameters which describe what the mass storage device looks like We will cover these parameters several times with a slightly different perspective each time We have to begin somewhere and what s good for the DOS is not always good for the BIOS The size of the blocks of disk space used by the concerned format is a trade off decided upon by the author of the BIOS It is said that who writes the BIOS owns the company There are many reasons why this is true and we will discover them The allocation block
168. tween actual and desired course is provided While feedback provides a means to reduce error by measuring the activity it can also create system instability cause overshoot and exhibit undesirable transient response An 14 example of potential instability and undesirable response would be if the driver of the automobile were drunk or had to rely on in formation verbally transmitted to him by another observer With this in mind it is important to have the capability to assess a control loop s characteristics In particular one of the first issues requiring resolution is that of loop stability Since loop stability accuracy and transient response are all related to loop gain the loop gains for which the loop remains stable are another area of interest The question of loop stability with respect to loop gain arises because loop element gains may change due to environment and loop accuracy is strongly affec ted by loop gain When the issues related to loop stability have been resolved the designer then turns to concerns regarding loop transient response This defines the loop response to a step change in in put to the control system One method for studying and predic ting the behavior of closed loop systems is called the root locus method The root locus method attempts to calculate the roots of the denominator of the closed loop transfer function H s for the control loop With this method the transfer function is determined in
169. uch as the video and casette Storage are obsolete but he has some very good discussions on the CPU and programming as well as the operating theory of computers in general My soldering iron is warm now If this project works I will let you know If anyone is interested in developing sof tware of the type described above the assistance would be appreciated The profitability of this system is close to ab solute zero that s why it should be in the public domain N E Editor s Note The documentation will be very much appreciated for our reference files which will be used to assist people working with older systems Can anyone help with the info needs His project sounds interesting and if enough readers express an interest we ll try to get him to submit an article in the meantime if someone is willing to assist him with the software contact TCJ for his address Ever Wondered What Makes TURBOPASCAL Tick Source Code Generators by C C Software can give you the answer The darndest thing I ever did see if you re at all interested in what s going on in your system it s worth it The Jerry Pournelle BYTE Sept 83 fully commented and source code for your Pascal SCG TP program produces labeled TURBO system To modify just edit and assemble Version 3 00A 280 is 45 SCG s available for CP M 2 2 45 and CP M 75 Please include 1 50 postage in Calif add 6 5 C C
170. ust complete a year long research project and Senior Thesis I am building a portable laser ranging device and I want to hook the experiment up to a ZX81 computer The laser will stop and start a timer as it is shot and returns from a target I want to send the time to a program that will calculate the distance to the target I was wondering if you have had any prior experience with this particular computer and if you could give me some advice or suggest someone who could I would be most grateful for any help E T Editor s Note Is anyone willing to of fer some help or comments on this project even if it doesn t concern the ZX81 8 Bit Fan To date I have found TCJ to be the best publication of many that land on my desk in a week Always good solid hands on in formation Hopefully you will not go the IBM route as did another magazine We broke our rule with them about more that a one year subscription and after a couple of issues off they went predominantly IBM Reading items of in terest to us in it takes less that five minutes and we are not renewing for that reason Somewhere you got our initials shor tened up regarding the hard disk problems in issues 25 and 26 the initials should have been JTL not JT The reply from Tom Hilton in issue 26 was very interesting but not an answer Cer tainly we agree with the 8MB limit BUT our question was how do we add say _another 40MB drive to an SB180 system Our BIOS ca
171. vides us with information as to the optimal loop gain and 1 LOCIPRO SPP and PDP are Professional Engineering Software products from BV Engineering 2200 Business Way Suite 207 Riverside CA 92501 phone 714 781 0252 The Computer Journal Issue 27 relative stability of the compensated system SPP will be used to verify that the response of the system is now acceptable PDP 18 used to make all the plots for these examples Imaginary Axis Real Axis Figure 2 Typical System Responses The stable platform control system shown in Figure 3 con sists of a platform an angular rate sensor and a torque motor to move the platform In this system a desired rate is input to the system and the amplifiers feed a signal to the torque motor which in turn causes the platform to rotate at a particular angular rate The actual rate is fed back to the control loop to allow the loop to accurately follow the commanded rate Rate Sensor Primary Lens Optical Sensor Position Sensor Figure 3 Stable Platform Control Feedback System It is desirable to have as high a loop gain as possible in order to maximize steady state accuracy of the closed loop The system requirements demand that the system settle to the desired steady state final value within 0 1 seconds for a step in put Figure 4 shows the block diagram of the components of the loop in the LaPlace domain The loop elements describe the characteristics of the gain
172. wer of the new CPU s will be multiuser multitasking systems employing mutiprocessors and will require a the BDOS liking CP M 2 2 45 The Computer Journal Issue 27 reliable bus structure which provides for interprocessor communications and multiprocessor communications I m sure that many readers will comment on my negative stand on the current multitasking and multiuser implemen tations and that s because I feel that the currrent systems do not have suf ficient power to properly execute these feature If we don t need these features then we don t need the new chips either I m happy with my 8 bit systems with hard disks for wordprocessing which is the majority of my work I ll probably upgrade to solid state RAM to speed things up a little and avoid the disk noise but I surely don t need a 16 bit or 32 bit CPU and I don t need multiuser or multitasking for our operation although other larger operations may well need this Eight bit systems are cheap and if I want to do several things at the same time I just use several systems at the same time I am very interested in the new chips for other applications but when I choose a powerful chip because of its features I insist on being able to use ALL of its speed and power If limited power is ac ceptable I can provide that with existing CP M or PC DOS equipment If more power is needed then I want to be abl
173. x max xl x max void draw x2 y2 color else if yl lt y min int x2 y2 color dx y min void do pixel move yl 7 y nin int dx dy incrl incr2 incr3 d x xl y yl xend yend elee if yl gt y max clip cur x cur y x2 y2 xl dx y cur xj yl y max yl cur y dx abs x2 x1 dy abs y2 y1 128 ONSS 19 941 r4 C Column 27 Listing 2 if dy lt dx absolute value of slope is lt 1 if gt x2 start at point with smaller x co ord 1 x x2 y2 xend xl dy y2 yl x xl y xend x2 i dy y2 yl d dy gt 0 incrl dx incrl dx incrl dy lt lt 1 incr2 dy dx lt lt 1 incr3 dytdx lt lt 1 do pixel x y color while x lt xend x if d gt 0 if dy lt 0 d yu d else if dy gt 0 d else d incr3 do_pixel x y color else if yl gt y2 x yend yl dx x2 negative or zero slope positive slope x xl yend y2 dx x2 xl d dx gt U 7 incrl dy dy incrl dx lt lt 1 2 dx dy lt lt 1 incr3 dxtdy lt lt 1 do pixel x y color while y lt yend y 1 if d gt U if dx lt U d incrl
174. y copyrighted by Richard Conn Denis Wright and Echelon To sell and support Z System is one reason Echelon is in business Last those who receive Z System fully installed on their computer e g on Micromint s SB180 and want to become involved with the Z System community should subscribe to our fortnightly newsletter Z NEWS It sells for 24 00 per year Also we have a free catalog of interesting Z80 and HD64180 Z System and CP M compatible software produc ts Additionally we support over 60 remote access systems called Z Nodes around the world acting as electronic forums for people interested in Z System Frank Gaude President Echelon Inc The Computer Journal Issue 27 Computer Corner Continued from page 52 cheap it is standardized plenty of sup pliers biggest assortment of cards and CPUs think the biggest thing goihg for the STD bus is the manufacturer s in novative abilities There are several manufactureers who have complete systems with 3 inch disks all in a stan dard cage running compatible PC operations The most important aspect is support and STD bus people have been suppor ting other manufacturers for some time and know just what they need One com pany I have had some experience with is Giddings and Lewis they make big lathes as well as the electronics to drive them We happen to have their old style systems but they also make STD produc ts or I should say they buy most of the

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