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1. SC 7 CH CR 54 LN SC PHDG 10240 2 DO 1 1025 MOD BK 6 BLOCK CE DUP IF DUP EMIT 10 R 0 1 2 3 4 5 PRTDOC DUP BK BLOCK print diagram from spec scr 6 7 8 9 IF LN 6 1 DUP LN z 10 IF PHDG THEN THEN 11 ELSE LEAVE THEN LOOP 12 13 PDOC 230 PRTDOC print last generated diagram 14 15 gt Page 31 SCR 4 110 O stack diagram package 8 of 14 B A Cole 810326 1 TEXT C SUM SWAP O true if 2 strings differ e DO OVER I CE OVER I CE SUM 1 LOOP 2 2DROP SUM i WIEST OVER DUP C t SWAP TEXT test 2 words for lt gt 7 DOC SCRST HERE 32 WORD DUP CO 1 ALLOT document 1 def 8 BLK 6 gt R IN 6 gt R O IN SWAP BLK E BEGIN 58 WORD IN 6 gt R 32 WORD find colon word 10 HERE WTEST 11 WHILE R gt 1024 x 12 IF NOT FOUND ABORT THEN REPEAT 13 DROF R gt IN 1 STACK now go from here 1 COMPILE FORTH R gt IN R gt ELK 1 15 gt from Barry A Cole Los Angeles CA 213 390 2551 K 111 TRIAD SCR 111 A et Vn Eu N QOO D ON EUN O Uu e 00 ON OUV wn O e Am DW mash SCR Ww ON Cun ZNO 10 11 12 13 14 15 stack diagram package 10 of 14 B A Cole 610425 PSH 2 IFPTR IFPTR O 1 SAV HERE PSH SP DEPTH 1 DUP DUP HERE SWAP DUP ALLOT CMOVE RST IFPTR 6 8 DUP 6 DUP 2 ROT SWAP DUP IF 0 DO DUP SWAP 2 LOOP THEN DROP KILL 2 IFPTR
2. CSP and CSP are currently used in and respectively to ensure that all structures in the definition have been completed before the semi colon Any structures uncompleted will leave data on the stack and thus allow CSP to flag the error These words can also be used to check the stack effect of user defini tions For example if a definition should have no stack effect leaves the same number of items on the stack as it removes the following would test this FORTH DIMENSIONS 111 1 CSP cccc CSP which would execute a definition named cccc and issue a Definition Not Finished error 20 if the number of items on the stack at the beginning and end of the definition were different PAIRS This word is used when testing for correct structure in compiler directives see STRUCTURE ERRORS to check that the value of the two numbers on the stack is the same If the value of the two compi lation conditionals on the stack is not the same a Conditionals Not Paired error 419 occurs PAIRS can be used to test similar situations in user programs but the error message given will be the same error 19 The checks on the dictionary and stack consist of testing the stack for under flow the dictionary and stack for over flow and the name of the dictionary entry to be created for uniqueness in A FORTH this test is optional and there is a test to ensure that a definition name is not null Some of the tests are performed
3. Memphis TN 38134 901 377 3503 Page 14 COMPILER SECURITY George W Shaw III SHAW LABS LTD 17453 Via Valencia San Lorenzo CA 94580 How it Works and How it Doesn t Adapted from a section of the Acropolis A FORTH manual There is much argument about parameter validation and error detection in FORTH Many problems exist with many good solu tions Fig FORTH and its derivitives have taken one route of extensive protection in compiler directives and their associated words This is not an only solution in this area Its extensiveness may not be necessary There may be better alterna tives Read on learn how fig FORTH works consider the options and then decide Your opinion and ideas are needed Fig FORTH and its derivitives provide a type of compiler error detection referred to as compiler security Compiler security provides protection against structural programming errors made by the programmer as well as insuring the proper machine state and in a very few in stances the validity of parameters Though it depends on the type of program ming the most common errors are struc tural errors machine state errors and then parameter errors respectively structural errors may be caught internally by detecting parameter errors See text STRUCTURAL ERRORS The compiler security system uses two methods to trap structural programming errors inside of colon definitions Structural errors are those caused by
4. defined on page 3 of the Standard to be a 16 bit memory location The word MOVE is defined on page 26 to trans fer 16 bit words cells while the word CMOVE on page 20 is defined to move bytes not cells If the C does stand for cell what is the rationale Why was the former stan dard s B for byte replaced by the mysterious C I note that in the reference section of the Standard the word DPL which formerly used to handle both input and output point situations now strongly emphasizes that input con versations should not affect its FORTH DIMENSIONS III l value What is the reason for this restriction How likely is it that this may become part of the Standard CREATE is not Does the second sentence When name gt is subsequently executed the address of the first byte of lt name gt s parameter field is left on the stack mean that the word CREATE alone is to function this way The definition for clear or only when followed by CODE or DOES gt In other words is it intended that CREATE work as in the FIG model or has its definition changed Taken literaliy FORTH 79 says that CREATE will generate an unsmudged header with the CFA point ing to the run time procedure for variables Is this what is intended COMMENTARY FROM THE FORTH DOCTOR Some computers apparently by Stan dard Team comment round quotients and remainders to smaller magnitude more negative Trucation of nega tive quotie
5. sign character is to be stored Why was this word changed from its former function between lt and gt 3 The word is defined as a non precedence word Is this a typo or is it intentional If intentional could you explain the rationale It seems that the number of occasions for which colon needs to be com Page 5 piled are few and could easily be handled by using the COMPILE operator ON the other hand syntax errors and typos often result in mistaken attempts to compile which when it s an immediate word can be flagged by the compiler The word CODE is defined as using the form CODE lt name gt END CODE However the word CODE says nothing about the corresponding form Our version of FORTH rquires that code level action routines defined by CODE also be terminated by the word END CODE Is this compatible with FORTH 79 The words FIND etc as defined in the Standard indicated a search of CONTEXT and FORTH only Is it considered an incompatibility if the CURRENT vocabulary is also searched if different The defini tion of VOCABULARY is not clear regarding the possibility of sub vocabularies such as ABC chained to XYZ chained to FORTH If this is allowed and ABC is the CONTEXT vocabulary is not ABC XYZ and FORTH searched What is the mnemonic significance of the C words such as C CMOVE etc Surely it doesn t stand for cell does it The term cell is
6. 56 77 88 99 OK PUSH MY STACK OK PUSH MY STACK OK PUSH YOUR STACK OK PUSH MY STACK OK PUSH MY STACK OK PUSH MY STACK OK PUSH YOUR STACK OK POP MY STACK 11 OK OK POP YOUR STACK POP YOUR STACK 2DUP 77 33 110 OK OK POP MY STACK 55 OK OK POP MY STACK 6 amp OK OK POP MY STACK 89 OK OK POP MY STACK 99 OK OK OK OK OK OK OK OK STACK MY STACK USER STACK EMPTY OK OK 11 PUSH MY STACK 22 PUSH MY STACK STACK MY STACK 307A 0016 OOOB OK HK UK EMPTY STACK MY STACK STACK MY STACK USER STACK EMPTY OK OK OK OK OK FORTH DIMENSIONS III l Note that the stack consistant with the 8080 architecture grows down in memory Following these stack parameters is the actual stack area which is allocated in the dictionary The PUSH and POP words are code defini tions for speed which push a 0 or 1 flag value to the top of the parameter stack Thus when the stack variable is subsequently executed this flag is used to differentiate between popping from the user stack flag 0 and pushing to the user stack flag 1 The assembly code is thus separated into two very similar exe cution loops which move stack data one word at a time until the proper number of words for the stack element have been moved these two loops differ only in the direction of the data transfer In both loops the A register contains the current word count which is intially set to the number of wor
7. EEEEECEEEEEFELEE FUATH GESTS FORTH INTEREST GROUP Volume Ill P O Box 1105 Number 1 San Carlos CA 94070 Price 2 00 ura Letters 4 Announcements SS FORT et Dialog fee o lt lt A Real Notes 10 J ProgrammingAids 13 FORTH Inc News 14 Parameter Passing 19 Compiler Security 20 n Userstack 23 AsStackDiagram Utility 33 Chapters Meetings FORTH DIMENSIONS Published by Forth Interest Group Volume li No 1 May June 1981 Publisher Roy C Martens Guest Editor C J Street Editorial Review Board Bill Ragsdale Dave Boulton Kim Harris John James Dave Kilbridge Henry Laxen George Maverick Bob Smith John Bumgarner FORTH DIMENSIONS solicits editorial material comments and letters No responsibility is assumed for accuracy of material submitted ALL MATERIAL PUBLISHED BY THE FORTH INTEREST GROUP iS IN THE PUBLIC DOMAIN Information in FORTH DIMENSIONS may be reproduced with credit given to the author and the Forth Interest Group Subscription to FORTH DIMENSIONS is free with membership in the Forth Interest Group at 12 00 per year 24 00 foreign air For membership change of address and or to submit material the address is Forth Interest Group P O Box 1105 San Carlos CA 94070 HISTORICAL PERSPECTIVE FORTH was created by Mr Charles H Moore in 1969 at the National Radio Astronomy Observatory Charlottesville VA It was created out
8. T B STYP SWAP DUP ROT SWAP DO spool word I SPIT LOOP 32 SPIT 32 SPIT d MTYP 2DUP STYP TYPE 2 SPACES SP type and spool word 13 PWRD DUP C 72 gt 1 IF ERR ABORT print encoded word 1 un c ELSE COUNT MTYP THEN lt gt 00909 from Barry A Cole Los Angeles CA 213 390 3851 99909 OK S A LLL LLL LL LL OL P a i t tnt as t ttm FORTH DIMENSIONS III l Page 30 105 TRIAD SCR 3 105 O stack diagram package 4 of 14 B Cole 410325 1 PSTAK DEPTH IF SP 2 SO 2 print all words on stack 2 BEGIN DUP 8 PWkKO 2 2DUP END 3 DROP DROP THEN 5 HEX T 8 3B01 DECIMAL test for not semicolon 6 7 C SWAP COUNT DUP ROT SWAP 8 HERE 14 SWAP CMOVE DUP HERE 14 9 ROT COUNT ROT SWAP DUP gt R CMOVE 10 R gt DUP HERE DUP ROT SWAP 11 C SWAP t ALLOT concatenate 2 words 12 13 gt 14 15 SCR 4 106 stack diagram package 5 of 14 B A Cole 810326 7NUM DUP 1 C 45 test if input is number 1 2 BEGIN 1 DUP C6 16 DIGIT 3 WHILE DROP REPEAT CA 32 i U HEAD CR 13 SPIT 10 SPIT DUP print line headerj 5 COUNT 10 MIN SWAP OVER MTYP 11 6 SWAP O DO 32 SPIT SPACE LOOP 7 124 SPIT 32 SPIT SP 8 MVB ROT DUP 14 SWAP setup for MVDEL 9 MVDEL BEGIN MVB Ce gt R MVB I SWAP C sre dst len 10 ROT DUP R gt END ROT 2DROP move a to d til delim 11 G HERE HERE PAD HERE 1 O MVDEL string into memory 12 HERE 1
9. changed from before the ELSE it issues a warning and calls SKBD to allow the user to correct a stack depth disparrity between the IF and ELSE clauses tm VARIABLE A defining word which causes the name of the defined word to be put on the stack when that word is encountered 102 TRIAD SCk Y 102 O stack diagram package 1 of 14 b A Cole 6810326 l i eDROP DkOP DROP gt 1 2 5 Calling sequences 6 screen DOC defname 7 screen SDOC 8 PDOC 9 10 DUC builds stack diagram for one definition 11 SDOC builds stack diagrams for entire screen 12 PDOC prints stack diagram built by DOC or SDOC SCR 103 stack diagram package 2 of 14 B A Cole 810326 O VARIABLE SPOOL offset into spooled print file O VARIABLE SPL O VARIABLE T1 O VARIABLE SUM 0 1 2 3 pointer to current input word 4 in TEXT true for difference 5 0 VARIABLE LN line number being printed 6 0 VARIABLE BK base block for spooled diagram T O VARIABLE SC current screen spooled 8 0 VARIABLE IFPTR address of top of IF stack 9 O VARIABLE IFST 20 ALLOT define IF stack 10 IFST IFPTR and initialize to empty 11 gt 12 13 14 15 SCR 4 104 O stack diagram package 3 of 14 B A Cole 810326 1 SPIT SPOOL 8 1024 MOD 9 MIN 230 e BLOCK CI 1 SPOOL UPDATE spool one character 3 l SP SPOOL O SPIT SPOOL mark spool file end 5 6 DEPTH SO 6 SP 2 1 compute stack depth
10. circulated FORTH IF HONK THEN or alternately LOVE FORTH IF HONK THEN Just thought you might like to know ed Dear Fig TGIF is very interested in swapping listings with other Fig FORTH groups Our current listings are 2 Decompilers Full Screen editor CASE statements for 8080 Z80 and 6502 6502 Assembler TGIF FORTH INTEREST GROUP TULSA Box 1133 Tulsa OK 74103 How about sending them in to FORTH DIMENSIONS ed Page 2 Dear Fig I was lucky enough to attend one day of the recent West Coast Computer Faire and to meet some of the mentors of FIG I had numerous questions and enjoyed talking to Bill Ragsdale and others about them By the way for those of you who couldn t make it to the Faire the FIG booth was one of the most crowded People were standing there like no where else even as the 5 00 closing approached We all owe a thanks to the dedicated folks for their time and effort in this endeavor promoting and spreading the word of FORTH and FIG One of my questions to Bill was How can we remote members contribute to FIG in ways other than articles for FORTH DIMENSIONS I got a number of project ideas for one of which I need the help of the whole membership So PLEASE NOW HERE THIS I propose to assemble a book of utility program packages for publication by FIG I have a list of functions which I think should be included This covers such things as editors both the current FI
11. incorrect program structure either improper nesting of structures or not completing a structure inside of a defi nition Either of these conditions would cause the program to compile incorrectly Page 15 and could cause disastrous effects i e a system crash at run time The methods used by the compiler security system entail either checking a value on the top of the stack to verify the proper nesting of structures or checking that the stack position is the same at the end of a defi nition as it was at the beginning of the definition to ensure program structure completion These two methods probably trap about ninety percent 90 of the structural programming errors that a pro grammer might make The first in each of the paired struc tural compiler directives i e pairs such as IF THEN DO LOOP etc leave on the stack at compile time a value which is checked by the ending structure to ensure the proper nesting of structures For example the word IF leaves in addition to the other data necessary to compile an IF the value of two 2 on the top of the stack The words ELSE and THEN remove a value from the top of the stack and check to see if it is a two 2 If the value on the stack was not a two 2 a Conditionals Not Paired error f19 results and compilation is termi nated control returns to the keyboard If the value is a two 2 the remainder of ELSE or THEN executes removing the necessary data from the
12. necessary to make your ideas publishable On the aesthetic side you will find this edition con tains several photographs and art illustrations This is a FORTH DIMENSIONS first and you can expect to see more in the future Photographs and art illustrations will be chosen and published on the basis of their educational and human interest value This issue also introduces the character HEX who wil be FORTH DIMENSIONS official comic strip You will find the HEX comic strip in future editions of FORTH DIMENSIONS HEX s adventures will be a com bination of humor and education Ideas for HEX comic strips are welcome C J Street Editor PUBLISHER S COLUMN Renewals and new members are coming in at a fast pace We expect to climb to 3 000 members in the next few months and to 5 000 within a year Both the Computer Faire in San Francisco and the Computer Festival in Trenton New Jersey were huge successes We ll be in both again next year I d like to know of any other shows where you think FIG should exhibit Good material is coming in for FORTH DIMENSIONS Keep it coming and send in your comments Hoy Martens FORTH DIMENSIONS III 1 LETTERS Dear Fig My company is developing business systems using FORTH and we would be interested in communicating with local FIGGIES as well as offering our input to FST FORML FIG and other applicable F acronyms since it is obviously in our interest to promote the spread and ac
13. of dissatisfaction with available programming tools especially for obser vatory automation Mr Moore and several associates formed FORTH Inc in 1973 for the purpose of licensing and support of the FORTH Operating System and Programming Lan guage and to supply application programming to meet customers unique requirements The Forth Interest Group is centered in Northern California Our membership is over 2 400 worldwide It was formed in 1978 by FORTH programmers to encour age use of the language by the interchange of ideas through seminars and publications Page 1 EDITOR S COLUMN The last edition of FORTH DIMENSIONS was the beginning of many changes in editorial policy and format All these changes are designed to make FORTH DIMENSIONS a practical and useful communications tool This practical approach continues In this edition you will find a number of utility programs that will make the task of implementing practical applications in FORTH easier and faster All of these utilities have been contributed by FIG members who have found them to be valuable tools The editorial staff thanks these contributors and would like to encourage all FIG members to share their ideas and experience f you have a programming idea or tool that you have found useful please send it to Editor FORTH DIMENSIONS P O Box 1105 San Carlos CA 94070 YOU DON T HAVE TO BE A WRITER the editorial staff wili provide whatever copywriting is
14. subtracts the boolean flag result from X 08 to generate the char acter to emit in response to a back space Toby L Kraft 7822 Convoy Court San Diego CA 92111 714 268 3390 This really needs expansion and gener ality How about terminals that need an escape sequence to clear screen i e form feed Toby HEX should be used insteat of X ed Dear Fig I wish to convey a concept which has greatly increased the clarity of my FORTH coding It has to do with in line docu mentation of the contents of the stack comments within parathesis Unfortunately none of the existing techniques space hyphens brackets or ordinal suffix provide the brevity and clarity that one becomes accustomed to with FORTH The technique which I have devised provides both It revolves around the backslash character which I refer to as under and the double hyphen which I refer to as leaves Using this terminology the following comment address count is read address under count leaves nothing and N1 N2 N3 is read Numberl under Number2 leaves Number3 FORTH DIMENSIONS 111 1 The under symbol imparts a clear verbal and graphic representation of the ordering of the stack contents and provides an elegant solution to a major problem encountered when transporting FORTH algorithms and source code Don Colburn Creative Solutions Inc 4801 Randolph Road Rockville MD 20857 Dear Fig Som
15. until the next Tests two strings for not equal SL A string constant used for building expressions when arithmetic or logical operations are encountered in the dia grammed input string stl st2 TEXT cond True if the two strings differ val l val 1 Decrements the top of stack value by one vl v2 2DROP Drops the top 2 elements off the stack and discards them This is the stack diagram redefinition of colon It diagrams the word following it instead of compiling It is invoked by colon as the very last definition from within this package stl st2 C st3 Concatenates two strings into a single combined string It is used to build expressions when operators are en countered in the screen to be diagrammed HEAD Prints the header for a line of output to the console and also the spool file SKILL Removes and discards the top of the IFST NFD addr This is called when the word being analyzed is not in the special stack vocabulary It checks for valid numbers If this test is passed it returns a pointer to that string Otherwise it invokes SKBD to get user help adr PSH e Pushes the address of a level of the stack values onto the separate IF stack This is used for IF ELSE THEN stack restoration and checking adr RST ell el etc Restores the stack from the IFST stack Does not affect the IFST adr SAV Saves current stack element list o
16. 0 END DROP ERASE LOOP DROP 11 EXPECT MOVE DROP LEAVE 12 SPACES DROP TYPE BEGIN LO 13 ENDIF THEN REPEAT THEN WHILE 14 AGAIN UNTIL 1 15 gt SCH 115 OU stack diagram package 14 of 14 B A 1 GWRD O GWRD 1 GWKD 2 2 G 1 lt MINUS G 3 63 3 6 3 amp ANDA 6 3 08 amp G 2 1 le l 3 6 2 1 1 1 5 6 2 2 2 2 G 2 2 3 2 72 6 GC 1 NOT GWRD I 7 GWRD here HERE here GWRD pad 8 2DROP cond ALLOT DROP a VARIABLE DROP GWRD CONSTANT VAR lt e 3 11 S QUIT gt QUIT 34 WORD 12 FORTH DEFINITIONS 75 1 t 15 SCR 116 0 1 2 3 4 5 6 7 B 9 10 11 12 13 14 15 9 from Barry A Cole Los Angeles CA OK 213 390 3851 0099 FORTH DIMENSIONS 111 1 FORTH CLASS Date June 22 26 Where Humbolt State University Arcata CA 95521 Who Kim Harris and Henry Laxen What Intensive 5 day course on the use of FORTH Cost 100 140 plus room and board How Call Prof Ron Zammit 707 826 3275 MMS FORTH FOR STRINGY FLOPPIES Kalth Microsystems will make available to all licensed MMS FORTH users a modified version that runs on the TRS 80 with an EXATRON stringy floppy This modification is said to make MMS FORTH operate as it would on a disk except for the speed Users retain the capability to switch back to cassette operation with a single com mand Imp
17. C for ten years as a character byte prefix Ignore if you can that a character is defined as 7 bits in the Stan dard This was a hotly disputed point with FIG and the Europeans for B yte and FORTH Inc and a couple of others for GC Kitt Peak was adamant before the meeting for B and other uniformity improvements Their representatives made no defense of the issue Historical precedence wins this one Reference Section is just left overs Only one vote of any team member was sufficient to maintain a Reference word on the list The Standard attempts to minimize system variables Increased usage of special variables is unlikely Things like DPS are delegated to applications The definition of CREATE is quite clear You have stated it and then correctly paraphrased it Other defining words may be used before DOES which help build a parameter field DOES rewrites the code field to its own code CPU CONSTANT DOES is equivalent to CPU CREATE DOES gt uA Page 6 TECHNICAL NOTES BUGS amp FIXES Dear Fig I have recently brought up FORTH on a 6800 system and find it to be a very easy and powerful system for microcomputers I have a mini computer with a cross assembler on it which I used to assemble the source after keying it in Naturally as soon as I got it working I wanted to change it I feel that the EXPECT routine and backspace handling could be improved Significantly by incorporat
18. DUP 1 DUP ROT SWAP DUP 13 IF HERE C ALLOT 14 ELSE 2DROP 2DROP O THEN 15 ESC PAD C 27 IF ESC ABORT THEN escape gt SCK 4 107 stack diagram package 6 of 14 BE A Cole 510326 VOCABULARY STACK O CONSTANT LLIMIT filled in later 0 1 2 3 SKBD CR DROP KEY DUP EMIT scan kbd for drop pusnes de 48 XOR DUP 9 lt 5 IF DEPTH 1 HIN O DO DROP LOOP 6 ELSE DROP THEN 7 BEGIN CR PUSH VALUE PAD BO B EXPECT ESC G HERE O END 9 10 NFD TI 8 NUM handle word not found 11 IF Tie number 12 ELSE SKBD SPOOL SPL undefined 13 Ti 8 HEAD DROP SPL SPOOL THEN 14 e gt 15 80888 from Barry A Cole Los Angeles CA 213 390 3851 eenre OK 108 TRIAD SCR 4 105 O stack diagram package T of 14 B A Cole 8163206 1 F ND FIND DUP IF 2DkOP DUP LLIMIT gt 5 IF 1 ELSE Os THEN THEN Doo f stack diagram redef of 5 BEGIN FIND HERE DUP DUP Ti word to mem and printed 6 CO te ALLOT HEAD T 7 WHILE IF CFA EXECUTE ELSE NFD THEN execute each word and 8 2STACK PSTAK REPEAT print stack 9 DROP PSTAK CR 13 SPIT 10 SPIT SP SP 10 19 SCKST O SPOOL DUP 256 MOD reset spool ptr and place 12 SWAP SPIT SPIT sereend in spool 13 ta SDOC SCKST STACK LOAD document 1 screen 15 COMPILE FORTH gt SCR 109 stack diagram package B of 14 B A Cole 810326 PHDG 12 EMIT print heading on top of page STACK DIAGKAM SCREEN
19. ENSIONS III l PARAMETER PASSING TO DOES gt David McKibbin Sygnetron 2103 Greenspring Drive Timonium MD 21093 Often in programming one runs into the case where several different processes share similar structures Not wanting to waste time or space for redundant code the programmer usually creates a sub routine or procedure to execute the basic structure Then the individual processes merely pass arguments to the prodecure to accomplish their task Several schemes can be used to pass these parameters In simple cases the stack can be used directly This is the typical act of programming in FORTH DELAY 0 DO LOP SPIN FOR A WHILE 100 DELAY COUNT PASSED ON THE STACK However as the procedures get more com plex it gets more and more difficult to keep track of the passed parameters espe cially when the procedure itself is using the stack heavily Also many times it is necessary to pass not only numbers but operators or words as parameters One means of accomplishing this is via BUILDS DOES gt Parameters will be stored in the parameter field of the newly defined word and accessed from DOES gt via a new word 1 will push the first parameter on the stack 2 will push the second etc All parameters are 16 bits Varia ble R is used to store the parameter base address 1 DUP RF PARAMETER PUSH THE N TH EXAMPIE BUILDS DOES Rb 1 2 EXEQUE EXAMPLE ZZZ 90 EMITCFA TYPEA
20. G line oriented editor and a video screen type editor string processing data structures extended math double prec ision as an example math functions sin log etc matrix operations and float ing point routines No doubt there are others to be considered and I solicit your suggestions The plan I propose to compile and publish such a document is as follows l Members are asked to send their proposals for implementing utility packages to me at the above address or through FIG These proposals should consist of well documented lots of comments fig FORTH source code accompanied by complete instruc tions for use any known operating limitations and a brief technical description or reference if appro priate The programs should be as transportable as practicable if system unique routines are necessary Page 3 enough information should be provided so as to allow them to be adapted to a different machine I will compile a draft of the pro posed publication and submit it to a technical review committee for review and appropriate testing This com mittee of FIG members I am looking for volunteers will scrutinize the proposals and alternatives if appro priate test them on a running FORTH system and make recommendations I will then compile the final version and submit it to FIG for publication I have set some timelines for com piling this compendium such that it can be published by next year s Comp
21. IF 017 ELSE QUIT THEN AGAIN Page 7 Modifications to the fig FORTH boot up literals 1 Backspace Character Character to emit in response to a backspace entry X 08 control H is character FORTH responds to for backspace function Character to emit is terminal dependent and should be defined in the user table This also allows use of a printable character e g C to emit for backspace for use on printing terminals 2 Form Feed Character Character to emit to cause terminal or printer to advance to top of form This is also device dependent and should be in user table 3 Form Feed Delay Number of null characters to emit after issuing a form feed charac ter This is similar to CR LF delay which is already provided Recommendation Add variable BSTOF to user table X BBFF two characters of data FF form feed character X OC initial value BB back space character X 08 initial value Add word BSTOF to vocabulary to access this variable in user table Similar to BASE Modify definition of current user varia ble DELAY to include formfeed delay in upper byte Add word DELAY to vocabulary to access this variable in user table Modify startup parameters and cold start accordingly FORTH DIMENSIONS III l Modify EXPECT to use user defined backspace character and to explicitly generate bell code X 07 Currently EXPECT tests for the beginning of the buffer and
22. Listings of fig FORTH for specific CPU s and machines The above manual is required for installation Check appropriate box es Price per each e 1802 6502 6800 6809 o 8080 8086 8088 9900 APPLE Il o PACE ALPHA MICRO __ PDP 11 NOVA 10 14 PROCEEDINGS 1980 FORML FORTH Modification Lab Conference 25 35 T FORTH 79 Standard a publication of the FORTH Standards Team 10 13 I Using FORTH by FORTH Inc This is the best users manual 25 32 m Kitt Peak Primer by Stevens An indepth self study primer 25 35 TP BYTE Magazine Reprints of FORTH articles 8 80 to 4 81 5 8 ix FIG T shirts Small Medium Large X Large 10 12 Poster 1981 Calendar Aug 1980 BYTE cover 18 x 22 5 8 am FORTH Programmer s Reference Card If ordered separately send a FREE stamped addressed envelope TOTAL NAME a ci AMS OAF ORGANIZATION IF company address ADDRESS MN Bs TA TE IP COUNTY VISA f MASTER CHARGE s Minimum of 10 00 on charge cards Make check or money order in US Funds payable to FIG All prices include postage No purchase orders FORTH INTEREST GROUP PO BOX 1105 SAN CARLOS CA 94070 FORTH CLASSES June 22 26 Humboldt State Eureka CA See Page 32 June 23 amp July 24 College of Notre Dame Belmont CA See Page 4 LEARN FORTH FORTH INTEREST GROUP P O Box 1105 San Carlos CA 94070 Address Correction Requested BULK RA
23. M MOV RP SHLD SAV IP H POP B POP PUSH POP FLAG C A MOV BORA Os IF POP DATA FROM NSTACK TO PARAMETER STACK M A MOV WROS ELE H DCX M B MOV H DCX M C MOV CSP IN BC eee BLOCK i151 NSTACK DEFINITION CON T BEGIN MOVING DATA WORDS AT A TIME PSM PUSH B LDAX B INX A E MOV B LDAX 8 INX A D MOV PSW POP COUNT D PUSH DATA FROM NSTACK A DCR Os END ELSE PUSH PARAMETER STACK DATA TO NSTACK M A MOV H DCX M B MOV H DCX M C MOV CSP IN BC BEGIN TO PUSH DATA D POP PSW PUSH COUNT B DCX DA MOV B STAX B DCX E A MOV B STAX PSW POP A DCR Os END THEN C M MOV H INX B M MOV SAVE NE RP LHLD M E MOV H INX M D MOV gt CSP e H INX RP SHLD NEXT JMP BLOCK 4 152 STACK TYPE VARIABLES CON T gt CODE POP O H LXI PUSH JMP CODE PUSH 1 H LXI PUSH JMP STACK 1 NSTACK I INTEGER ELEMENTS DSTACK 2 NSTACK t DOUBLE PREC INTEGER ELEMENTS FSTACK 3 NSTACK FLOATING POINT ELEMENTS USER AIDS WHICH CANNOT BE COMPILED EMPTY STACK NNNN EMPTIES THE USER STACK NNNN BY RESETTING ITS STACK POINTER EMPTY STACK 31 C DUP 3 SWAP y STACK NNNN PRINTS OUT THE CONTENTS OF THE USER STACK STACK J C DUP 3 OVER DUP O gt IF 1 gt L SWAP DUMP ELSE 2DROP T USER STACK EMPTY THEN 4 ts e m ni UR OK OK OK 100 STACK MY STACK OK 35 STACK YOUR STACK OK OK 11 22 33 44 55
24. MAL BASE ee Page 10 Here is an adaptation of George Shaw s VIEW to use the word WHERE which on my system invokes a full screeen editor that highlights the word pointed to by a block number and displacement It certainly helps pick out a word in dense code SCR 66 O VIEW USING WHERE 4 15 81 REE 1 ADAPTED FROM FORTH DIMENSIONS VII NBR 6 P 162 2 FORTH DEFINITIONS 3 500C lt BIK ING 3 SAVE BLK AND DISPLACEMENT 4 CONSTANT gt DOC lt COMPILE CONSTANT REBUILD THE WORDS 5 VARIABLE gt DOC lt COMPILE VARIABIE THAT BUILD WORDS 6 1 DOC lt COMPILE 7 CBUILDS Oo 5DOCXIOMMPIIE BUILDS 8 USER re orina 9 CREATE DOC lt COMPILE CREATE 10 VIEW IOOMPIIE NFA GET HEAD OF THE HEADER 11 DUP COPY THE ADDRESS 12 2 GET THE DISPLACEMENT 13 SWAP 4 GET THE BLOCK NUMBER 14 WHERE GO SHOW amp HIGHLIGHT 15 de HELP WANTED Senior Level FORTH Programmers Friends Amis 505 Beach Street San Francisco CA 94133 Call Tom Buckholtz 415 928 2800 Intermediate amp Senior Level FORTH Programmers for Data Entry Applications MSI Data 340 Fischer Avenue Costa Mesa CA 92627 Call Joan Ramstedt 714 549 6125 PRODUCT REVIEW by C H Ting Feb 26 1981 Timin FORTH from Mitchel E Timin Engi neering Co 9575 Genesee Ave Suite E2 San Diego CA 92121 714 455 9008 8 single density diskette 95 00 I was invited by Dr
25. STACK DEFINITIONS HERE LLIMIT gt Vie stack diagram package 11 of 14 B A Cole 810425 THEN DEPTH IFPTR 6 14 C DUP IF 128 2DUP IF CR STK ERROR ELSE THEN SKBD ELSE 2DROP THEN ELSE DROP THEN KILL ELSE DEPTH 128 gt R SP RST R gt IFPTR 6 6 14 C IF DROP SAV FORTH DEFINITIONS gt 113 stack diagram package 12 of 14 B A Cole 810326 GBLD IN 32 WORD HERE C 1 ALLOT GWRD IN 6 BUILDS GBLD DOES GWRD GWRD G 1 IN 6 BUILDS GBLD DOES SWAP SWAP C C G 2 IN 6 BUILDS GBLD DOES C 3c SWAP C G 3 IN BUILDS GBLD DOES SWAP C C C SWAP C 41 WORD IMMEDIATE gt from Barry A Cole Los Angeles CA 213 390 3851 90 OK FORTH DIMENSIONS III l Cole 810425 P OVER OVER HEX HEX 2 MSG BLANK T DROP DUP DUP 3 LOOP DROP ob sak 7 OR iF 5 Cole 410425 CWRD 2 6 3 6C 3 G 3 XOR G 2 2 24 2 G 2 2 2 2 GWRD cond PAD pad IABLE 114 TKIAD SCH 114 O stack diagram package 13 of 14 B A i 2 STACK DEFINA TIONS le da 3g WORD HERE DUP C 1 ALLOT 4 DUP DUP ROT ROT SWAP SWA 5 A gt DROP DROP DROP DROP 6 DECIMAL DECIMAL 2DUP 2DUP 1 DROP DROP Ct 7 50 DROP SPACE i B 21 1 DROP DROP ALLOT DROP 9 C DROP DO f DUMP 1 EMI 1
26. TE U S POSTAGE PAID Permit Mo 261 Min View CA
27. TH Arrange ments are also being made to produce the FORTH processor and we expect this project to start very soon LIFEBOAT REPRESENTATIVE VISITS Masa Tasaki Managing Director of Lifeboat Inc FORTH Inc s distributor in Japan spent two days at FORTH Inc recently to discuss mutual marketing plans Lifeboat Inc is one of the few software distributors in Japan and polyFORTH is the top of their product line Tasaki has installed over 40 polyFORTH systems in Japan in the past year and plans to sell an additional 50 polyFORTH systems by the end of 1981 STARTING FORTH BOOK PREPRINTS AVAILABLE STARTING FORTH a 380 page book intro ducing the FORTH language and operating system will be published by Prentice Hall this September in both hard and soft bound editions FORTH Inc is offering limited preprints to customers until then The preprint numbered and signed by both author Leo Brodie and Charles H Moore sells for 50 00 plus 6 sales tax for residents of California You may reserve a copy of STARTING FORTH by calling Winnie Shows at 213 372 8493 All orders must be pre paid Page 13 RECENT FORTH COMMERCIAL APPLICATIONS Work has just been completed for Raytheon Corporation on a terminal cluster up to 32 terminals with a single concen trator Each component of the system is controlled by an 8085 processor and all are programmed independently using polyFORTH This is a capability they ve never had bef
28. Timin to compare his CP M FORTH FD 11 3 p 56 with the Z 80 FORTH by Ray Duncan Laboratory Microsystems FD 11 3 p 54 FD II 5 p 145 I ran the two FORTH systems on his home made Z 80 computer S 100 bus 6 MHz The results of a few bench marks were Program Timin Z 8 LOOPTEST 7FFF O DO LOOP 2 3 sec 2 9 sec TEST 7FFF O DO I DUP DROP LOOP 5 9 7 4 TEST 7FFF 0 DO I DUP DROP LOOP 44 0 54 9 TEST 7FFF O DO 7FFF 1 DROP LOOP 74 3 88 6 WIPE 120 61 DO I CLEAR LOOP 34 3 81 8 97 LOAD four hundred eighty 9 s o 17 9 18 6 I was surprised that Timin FORTH which is 8080 fig FORTH ran faster than 2 80 FORTH which uses the extra Z 80 registers for IP and W Dr Timin s opinion was that the Z 80 instructions using these extra registers are slower then the simpler 8080 instructions The word WIPE tests disc access time Timin FORTH accesses the disc by 1024 byte blocks and it is twice as fast as Z 80 FORTH which reads writes by 128 byte sectors as in the fig FORTH model The dictionary in Timin FORTH is about 11 Kbytes including an editor and an assembler The editor is the same as that of the fig FORTH model The assembler has all the Z 80 instructions An interesting word SAVE allows the whole system in cluding application words to be preserved Page 11 FORTH DIMENSIONS 111 1 as a CP M file which can be loaded back for execution It maintains eight i Kbyte disc buffers The documenta
29. Z EXAMPLE SPC 10 SPACES CFA TYPE 10 SPACES Now that the mechanics are explained the following example will more fully demon FORTH DIMENSIONS III l strate its usage Both DUMP 16 bit dump and CDUMP 8 bit dump share a common structure with only a few inner words dif fering DUMPS is a new defining word used as a procedure for both DUMP and CDUMP U R O SWAP D R DUMPS BUILDS DOES Rf STORE PARAMETER BASE ADDRESS BASE R gt HEX SAVE BASE AND SET HEX OVER SWAP CONVERT TO BEGINNING AND END ADDRESS BEGIN CR DUP 4 U R 2 SPACES TYPE ADDRESS 1 0 D0 DUP 2 EXECUTE 3 UR 4 2DUP OVER 16 MD O OR IF LEAVE THEN LOOP 2DUP TERMINAL OR UNTIL DROP DROP CR R gt BASE RESTORE BASE DUMPS CDUMP 16 CACFA 4 1 2 ADDRESS 1 COUNT DUMPS DUMP 8 CFA 6 2 2 ADDRESS 1 COUNT What has been accomplished is akin to passing procedures functions as parameters in Pascal I expect that there are other ways to do this FORTH beyond what has been proposed FIG FORTH UNDER OS 65U Software Consultants has announced the availability of Fig FORTH under 0S 65U for the Ohio Scientific Line The package includes assembler and a terminal oriented editor and is available now for 79 95 This version is said to support hard disk multi user systems and may even be run in one partition and BASIC in another For more information contact Software Consultants 7053 Rose Trail
30. an example of using SEARCH We are searching for the string COUNT in screens 39 41 the source code of SEARCH is on screen 40 The screen and line numbers are shown for each hit Inci dently the search string may contain blanks Just type the first screen number the last screen number SEARCH followed by one blank and the target text string Conclude the line with return The routine will scan over the range of FORTH DIMENSIONS III l screens doing a text match for the target string All matches will be listed with the line number and screen number Happy SEARCHing 39 41 SEARCH COUNT 00 VARIABLE COUNT ER 2 40 1 COUNT ER COUNTER 40 1 COUNTER COUNT ER 4 40 56 DIF 0 COUNTER 5 40 12 EMIT 01 TEXT O COUNT ER 840 OK SCR M 40 Q0 SEARCH OVER RANGE OF SCREENS WFR 1 DECIMAL 2 00 VARIABLE COUNTER 3 BUMP THE LINE NUMBEK AND HANDLE PAGING 4 1 COUNTER COUNTER 5 56 gt IF 0 COUNTER 6 CR CR 15 MESSAGE 12 EMIT THEN 7 SEARCH FROM TO TARGET STRING 8 12 EMIT 01 TEXT 0 COUNTER 9 1 SNAP DO FORTH I SCR 19 EDITOR TOP 11 BEGIN 1LINE IF 0 M SCR BUMP THEN 12 1023 Ra lt UNTIL 13 LOOP CR SEARCH IS LOADED 5 14 15 TYPICAL USE TO LOCATE KEY UORD 21 44 SEARCH KEY UORK DD o tc PROGRAMMING AIDS amp UTILITIES Kim Harris FORTHRIGHT ENTERPRISES P O Box 50911 Palo Alto CA 94303 In true ideal FORTH programming style the definit
31. and CMOVE when desired Something as simple and extremely effec tive as the CSP and CSP in and respectively may be left in the kernel system to give warning to even the best of us when necessary Definitely also the stack checks at compile time and possibly the uniqueness though it should be optional and null definition currently A FORTH only checks should be left in but the structure and state testing is often incomplete and annoying Anyone who has tried to write and secure a good general CASE structure or a BEGIN WHILE REPEAT loop which allows mul tiple WHILEs will know what a pain it is to try to secure them in a reasonably complete fashion For these people compiler security dosn t work Addition ally new structures transported from my system to another may not remain secure because the same conditional pair numbers used in my structure on my system may have been used in a different structure on the other system Again the compiler secur ity dosn t work The same method used in high level struc ture testing is also used in one known assembler which the author considers totally inappropriate If one is program ming in FORTH assembler one is doing so for speed which may require not being structured at all Currently the matter of compiler security is being studied by the group writing the next 8080 fig FORTH version which could possibly outline a new model Should we have all the protection all the time
32. base block number for spooled stack diagram Page 27 LN Line number being printed Used for page headings SC Current screen number being spooled IFPTR The address of top of IF stack Used to restore values on stack for IF ELSE THEN construct IFST The area reserved for pointers to previous stack contents It is used to restore the stack on ELSE and THEN clauses SPL A temporary variable used by NFD to retreat the spool file to erase the unknown stack prior to operator specifi cation of what is added or dropped SPOOL Offset into spooled print file SUM The sum of differences in two strings Used in TEXT Value is 0 for a text match and nonzero if different Ti Pointer to current input word in memory type format CONSTANTS LLIMIT The limit address for dictionary search to keep from using standard FORTH words from within the STACK diagrammed words FUNCTIONS FIND pfa length true found a FIND false not found This is the same as FIND except that the true condition is set only if the work is found above LLIMIT This restricts the search to stack vocabulary words A string constant used for building expressions when arithmetic or logical operations are encountered in the dia grammed input string FORTH DIMENSIONS 111 1 Defined back to its original state after being used as a concatenation token this marks the beginning of a comment All text following it is ignored
33. ccess Corporation both of Belmont CA Beginners workshops start June 23 and advanced workshops start July 14 Classes meet every Tuesday and Thursday evening from 7 00 to 9 00 P M Registration is 135 for 3 weeks 12 hours For more information and registration contact College of Notre Dame 415 593 1601 Page 4 CONTINUING DIALOG ON FORTH 79 STANDARD Dear Bill We recently obtained a copy of the FORTH 70 Standard from FIG and are attempting to align our version of FORTH with it The document is generally well done and in most cases cleariy and con cisely expressed However there are about a half dozen or so definitions that seem to us somewhat ambiguous I am writing to you in the hopes that you can clarify the word definitions in question or that you can refer us to someone who can I am also interested in knowing whether the FIG model has been aligned yet if not when it vill be My list of questions is enclosed and I would appreciate anything you can do to assist us in their resolution Cordially Robert D Villwock MICROSYSTEMS INC 2500 E Foothill Blvd 102 Pasadena CA 91107 OPEN QUESTIONS FORTH 79 Standard 1 For the words and does the terminology rounded toward zero essentially mean truncated If not precisely what does it mean 2 The word SGIN is now apparently defined to be used outside of the lt f operators What is the pre cise definition of where the minus
34. ceptance of FORTH We re also confirmed FORTH fanatics David B Moens BUSINESS SYSTEMS SOFTWARE INC 27 East Kings Highway Haddonfield NJ 08033 609 429 0229 You are our kind of fanatic and we re happy to put the word out for you Dave ed Dear Fig Re Born again programmer and Born again FIGGER in FORTH DIMENSIONS I1 5 My interest in FORTH as a programming language does not envolve becoming mired down in the morass of a religion LE would be best to stay on rational grounds in the development of FORTH and leave religion to those who are unable to think without faith I will not take part in a religious group Therefore I will not be renewing my membership Larry R Shultis P O Box 218 Fontana WI 53125 Just goes to show you that there is more than one type of fanatic Keep the faith Larry OOPS sorry about that I meant Don t worry Larry FIG is not envolving your spelling into a religious group ed FORTH DIMENSIONS 111 1 Dear Fig Thank you for the prompt and efficient service I have received I realize that you can t have much time left to look after the rest of the world but without your interest it may never have reached these shores Spread the good WORD J Huttley UNIVERSITY OF AUCKLAND 19 Duncan Avenue Auckland 8 New Zealand You are very welcome ed Editor s note At the WEST COAST COMPUTER FAIRE in California two versions of a FORTH bumper strip were
35. d Wed MMSFORTH Users Group 7 00 pem Cochituate MA Call Dick Miller at 617 653 6136 for site Seattle Chuck Pliske or Dwight Vandenburg at 206 542 7611 Paul van der Eijk at 703 354 7443 or Joel Shprentz at 703 437 9218 Potomac Tulsa Art Gorski at 918 743 0113 Texas Jeff Lewis at 713 719 3320 or John Earls at 214 661 2928 or Dwayne Gustaus at 817 387 6976 John Hastings 512 835 1918 Phoenix Peter Bates at 602 996 8398 New York Tom Jung at 212 746 4062 Detroit Dean Vieau at 313 493 5105 FORTH Interest Group c o 38 Worsley Road Frimley Camberley Surrey GUl6 5AU England England Japan Mr Okada Presdient ASR Corp Int l 3 15 8 Nishi Shimbashi Manato ku Tokyo Japan Canada Quebec Gilles Paillard at 418 871 1960 West Germany Wolf Gervert Roter Hahn 29 D 2 Hamburg 72 West Germany 040 644 3985 Publishers Note Please send notes and reports about your meetings FORTH DIMENSIONS II1 1 FORTH INTEREST GROUP MAIL ORDER FOREIGN USA AIR Membership in FORTH INTEREST GROUP and Volume III 6 issues of 12 24 FORTH Dimensions Check one NEWor RENEWAL Volume Il of FORTH DIMENSIONS 6 issues 12 15 Volume of FORTH DIMENSIONS 6 issues 10 14 idm fig FORTH Installation Manual containing the language model of 10 14 fig FORTH a complete glossary memory map and installation instructions Assembly Language Source
36. dge The number is 415 538 3580 The system runs 24 hours a day Use a 300 baud modem and start with two returns the system is self instructing This conference holds information on employment vendors applications announcement calendar inquiries books etc Information of the conference is organized in a tree struc ture hence the name Conference Tree Our hope is that half of the callers will review the available material and then ask questions The other half should add answers to these questions You simply find a topic or message and attach your query response Users naturally organize their material in a form that facilitates retrieval This system was written in Cap n Software Version 1 7 Versions for other than Apple II are being developed For availability contact The CommuniTree Group Box 14431 San Francisco CA 94119 or call the original Tree 415 526 7733 THAT IN DECIMAL Page 12 FORTH INC NEWS MAJOR EXPANSION PLANS FORTH Inc is now entering a major expansion phase according to President Elizabeth Rather Appearing on a panel on Programming Languages for Small Systems at the recent NCC in Chicago Rather observed The level of excitement and enthusiasm about FORTH in the industry is tremendouus We are increasing our number of OEM S and we have been approached by several major silicon manufacturers desiring to obtain marketing rights for special versions of polyFOR
37. ds per stack element and decremented each time through the loop The BC register pair contains the current user stack pointer while the HL register pair contains the address of the stacks parameter field so that the new user stack pointer value may be saved after all words within the stack element have been trans ferred CONCLUDING REMARKS These user stacks have been optimized to provide rapid execution speed at the expense of high level transportability and error checking for a stack pointer out of bounds It is felt that the concept in whatever realization is important since it provides a very readable and structured method to temporarily store and sort data without having to resort to such unclean practices as using either explicitly addressed arrays or the return stack It s the type of FORTH word that once you have it prompts the question it s so obvious why didn t someone think of it before Page 22 NEW PRODUCT STAND ALONE FIG FORTH FOR OST FORTH Tools has announced stand alone Fig FORTH for all OSI mini floppy com puters that combines Fig FORTH with stand alone machine drivers by FORTH Tools With this system OSI 65D is superfluous with FORTH booting up directly yet the disk is OS 65D compatible Since FORTH Tools FORTH dispenses with the OSI operating system FORTH Tools has developed disk display and kevboard drivers for the OSI hardware FORTH Tools FORTH for OSI is strictly compatible wi
38. during the execution of other functions by the testing word such as the tests per formed by WORD and by CREATE Only the testing performed by these words will be described here CREATE This word creates a dictionary header for a new word In the process of creating this header a dictionary search is performed to check that the header is unique The message given if a duplicate is found is Isn t Unique 4 This is not a fatal error but just a warning A FORTH allows the disabling of this test and the associated message and performs another test for a dictionary entry whose name is a null The creation of a dic tionary entry with a null name is not allowed because the null is the name of the entry interpreted at the end of the disk or terminal buffers If an attempt to create a null entry is detected a Null FORTH DIMENSIONS III 1 Definition Name error 9 is given If a dictionary entry with a null name were created the system would attempt to interpret this as the end of the current buffer with unpredictable results STACK This word checks that the parameter stack is within bounds It compares the current stack position by executing SP against the base stack position in user variable SO to check for a stack under flow It also checks that there are at least 128 bytes of dictionary space left to leave room for PAD and stack work If the stack underflows an Empty Stack error 1 is given If the stack comes w
39. e time ago I bought your Installation Manual and the 6502 Assembly Listing I have been studying both for quite a while and am also a charter member of the Potomac FORTH Interest Group PFIG Joel Shprentz and Paul VanDerEijk I have MMS FORTH cassette for the TRS80 up and have just bought GEOTEC FLEX FORTH for my KIM although I don t have my 16K ram card installed in KIM yet I do like FORTH The PFIG has been fairly inactive for some time due to lack of a meeting place but Joel Shprentz has been conducting some Intermediate FORTH classes 30 for six lessons which are ongoing and very interesting we are well into lt BUILDS DOES gt and will then go on to disking etc Ask Joel for details I m still planning to bring up FORTH on the KIM from my own hand assembled ver sion just to satisfy my own curiousity about what makes FORTH tick I do think I m finally beginning to understand how everything fits together In this vein I have a few comments to pass on from an advancing novice FORTH enthusiast The first two comments regard the above referenced Installation Manual and 6502 Assembly Listing The last two are ideas of my own which I offer for what they are worth l There is a disparity in the Instal lation Manual version of the 6502 memory map regarding the placement of the Disk buffer and User Area Page 8 Indeed there is disparity in the 6502 Assembly Listing between what is done near the front and w
40. ere the compiler security system plainly does not work but there are probably more How is this apparently incomplete structure checking performed Read on The values on the stack is verified by PAIRS For example the words PAIRS BEGIN and AGAIN are defined as follows PAIRS 19 ERROR BEGIN COMP HERE 1 IMMEDIATE AGAIN 1 PAIRS COMPILE BRANCH BACK IMMEDIATE BEGIN first checks to make sure that it is being executed in compile mode inside a definition with COMP which issues an error if it is not It leaves the current dictionary address on the stack HERE as a branching reference for AGAIN and then the 1 as the first of a conditional pair When AGAIN later executes during the compilation of the definition it first checks the stack to see that a BEGIN preceded it at the same level of nesting by executing PAIRS PAIRS expects to find a matched pair of values in this case ones 1 as a matched set of condi FORTH DIMENSIONS 111 1 tional pairs If PAIRS does not find a matched set it aborts with a Conditionals Not Paired error 19 If the values on the stack are paired it removes them and returns The above simple form of error checking is very effective but as structures become more complex manipulating and maintaining the stack values can become cumbersome and unwieldy The above is also not yet complete One more check must be executed to ensure that the structures in the defi
41. get the source codes directly from disk and then to generate a printer format spool file also onto FORTH screens Keeping track of values when an IF was encountered and restoring them on ELSE and THEN was added This generates a warning message if the two paths leave different numbers of parameters on the stack Finally concatenation of strings for algebraic and logical expressions was added USAGE AND OPERATION The main routines called by a user are screen DOC defname to document 1 definition screenff SDOC to document a whole screen screen PRTDOC to print from given screen PDOC to print last documentation The program clears the display stack before each colon definition A search is made for the first colon on SDOC or the specified name following a colon on DOC The name of the function is displayed along with the currently empty stack con tents It requires user input to continue since the entry conditions of the routine are unknown It prompts DROP to see how many excess elements should be dropped from the stack A carriage return suf fices to leave it alone It continues with the prompt PUSH VALUE For each symbolic name of a value on the stack a free form name should be typed followed by a carrlage return The prompt will be repeated until a line consisting of only a carriage return is typed There are no limitations imposed on the input however it is advised that nulls and tabs should not be included as this
42. hat is actu ally implemented per the installa tion Manual The Installation Manual puts the Disk buffer at the top of RAM with the User area just below Line 0051 of the assembly manual says User area is top 128 bytes with disk buffer next line 0052 CREATE assumes just the oppposite in both the Installation Manual and Assembly Listing Editor correct on all all points The author was inconsistent 2 In screen 49 of the Installation Manual I see no need whatsoever for a dedicated word such as ID to move the word name to Pad and then type it out The first 4 words are not needed and neither are the words following PAD SWAP CMOVE PAD Just a waste of time and space to bring the name to PAD and then type it out Editor this is not so If you have WIDTH set to less than 31 ID is required 3 I would suggest a word Q that might be inserted into any type of loop DO LOOP or BEGIN AGAIN to allow a timely exit when things go awry as they do with Novices It s very simple Q TERMINAL IF QUIT ENDIF MMS FORTH has this embedded into the code of but I think that s overkill But it sure is nice to undo errors put into loops Editor this is terrible style LEAVE is the correct way for a controlled termination 4 This has specifically to do with the Jump Indirect of the 6502 as used in both the Installation Manual and the assembly listing Having used the 6502 for better than 4 yea
43. he fig FORTH at the West Coast Computer Faire April 1981 Top l r Michel Mannoni FORTH vendor Dave Boulton and Martin Schaaf Answering the question What s FORTH 10 000 times Bottom l r Roy Martens FD Publisher Anne amp Bill Ragsdale FIG prime movers Order your T shirt like Bill s FORTH DIMENSIONS II1 1 ANNOUNCEMENTS FORML CONFERENCE CALL FOR PAPERS Papers are requested for the three day technical workshop to be held next November 25th to 27th at the Asilomar Conference Grounds in Pacific Grove California Monterey Peninsula Although registration for this con ference is not yet open attendance will be limited to 60 persons Authors will be accepted before listeners so if you want to attend the only sure way is to write a paper Please note abstracts or propo sals for papers or discussions must be submitted no later than September 1 1981 for inclusion in the conference and its proceedings completed papers by Sep tember 15 1981 The purpose of this workshop is to dis cuss advanced technical topics related to FORTH implementation language and its applications Potential authors should write for an author s packet for detailed instructions Send all correspondence regarding the conference or papers to FORML CONFERENCE P 0 Box 51351 Palo Alto CA 94303 FORTH WORKSHOPS Beginners and advanced workshops in FORTH are being jointly sponsored by the College of Notre Dame and Inner A
44. he top of page heading and sets the lines per page count Used by PRTDOC blki PRTDOC a n rm rrr cm mk re ee m Prints the stack diagram from the spool file whose starting block is the specified blk PSTAK Prints all words from the string addresses on the stack The top element is printed to the right of previous elements The stack is unchanged adr cnt PWRD aoa Prints one word via MTYP Used by PSTAK REPEAT Functionally identical to the re defined THEN scri SCRST scri Resets the spool pointer and places the screen number into the beginning of the output spool to be used in top of page headers by PDOC scri SDOC Documents one whole screen by exe cuting it using the diagram definitions oo SKBD This scans the keyboard for user interaction It generates the DROP and PUSH VALUE prompts It is invoked whenever intervention is required in the diagramming process char SPIT Writes character out to disk spool file STACK This is the name of the vocabulary containing this package adr cnt STYP Similar to TYPE but spools to disk rather than typing to the screen Outputs an additional two blanks after the message adr Ts cond Tests the current string for a match to the FORTH word semicolon This is used to exit DOC THEN aan Re defined in the stack vocabulary this cleans up the IFST If the depth of the stack has
45. in 8080 assembly language for speed defines the execution time actions taken by the stack varia ble Both of these defining parts will be explored in greater detail below The format of the user stack in the dictionary is shown in Fig l It con sists of a normal FORTH header followed by the following four stack definition parameters a current stack pointer two bytes b words per stack element one byte c maximum stack pointer address two bytes d minimum stack pointer address two bytes BYTES FIELD COMMENTS 1 CHAR COUNT CHARACTERS characters saved for word name 2 VOCAB LINK 2 OWE ADDRESS Points to CODE part of NSTACK def 2 CURRENT STACK PTR E WORDS STACK ELEMENT 2 MAX SIK PTR ADDRESS 2 MIN STK PTR ADDRESS m STACK DATA AREA bytes needed to contain specified of stack elements Figure 1 Dictionary Layout for a Stack Type Variable FORTH DIMENSIONS III 1 eee BLOCK 150 STACK DATA TYPES PHH 23 OCT 60 C ELEMENTSILSWORDS ELEMENT NSTACK NNNN CREATES THE STACK CALLED NNNN WITH THE GIVEN NUMBER OF ELEMENTS STACK DATA TYPES MAY BE PUSHED OR POPPED TO OR FROM THE PARAMETER STACK NSTACK XBUILDS SWAP OVER DUP DUP BYTES IN STACK HERE DUP SET UP CURRENT STK PTR ROT C AHORDS STK ELEM MAX SP ADDR HERE MIN SP ADDR 10 ALLOT SPACE FOR STACK 9 1CODE WARAM 2 B LXI E DAD H PUSH HL PTS TO WWRDS ELE gt RP LHLD H DCX D M MOV H DCX E
46. ion of the en closed recommendations I also experimented with the GLOSSARY routine submitted by D W Borden in FORTH DIMENSIONS Volume 1 No 4 I modified it to handle the variable length name field and changed the format slightly Keep up the good work Toby L Kraft San Diego EXPECT 001 EXPECT MODIFIED FOR USER DEFINED BACKSPACE CHAR gt 002 26FEBS81 TOBY L KRAFT 003 EXPECT 004 OVER OVER 005 DO 006 KEY DUP amp ADD COUNT TO ADDRESS FOR LOOP LIMI gt GET CHAR AND SAVE COPY yd OE ORICIN GET SYSTEM BACKSPACE AND CHECK FOR IT gt IF 00 DROP DUP I LOSE CHAR CHECK BUFFER BECIN 3 010 DUP R gt 2 OR ADJUST BUFFER POINTER APPROPRIATELY 011 IF 07 ELSE BSTOF Ce ENDIF BELL BECINNING BS OTHERWISE 012 ELSE 013 DUP OD CHECK FOR CARRIAGE RETURN 014 IF 015 LEAVE DROP BL O PREPARE TO LEAVE 016 ELSE DUP ENDIF 017 I1C 01 1 STORE CHARACTER IN BUFFER 018 ENDIF 019 EMIT ECHO CHAR TO TERMINAL 020 LOOP 021 DROP O22 GLOSSARY 001 GLOSSARY GENERATOR ROUTINES 002 DECIMAL 003 O VARIABLE CMD 004 TOF CR CR 32 SPACES GLOSSARY CR CR GENERATE PACE HEADING 005 LEN WORD 15 SPACES NFA PFA CR CR 006 HEX 007 GLOSSARY TOF CONTEXT e e CMD 008 BEGIN CMD IF 009 CMD C 3F AND 010 DECIMAL DUP 3 R SPACE O11 F SWAP CMD ID SPACES 012 CMD HEX amp R SPACE 013 CMD 1 TRAVERSE DUP 014 3 6 R SPACE CR 015 1 CMD 016 TERMINAL IF QUIT END
47. ions contained within the screens clearly designates their use 81 LIST 82 LIST SCR 81 Software Development tools fig FORTH 1 x for LOADing LOAD sert gt DUP LOAD THRU lstScreen lastScreenf LOADs range of screens 1 SWAP DO I LOAD LOOP 0 I 2 3 4 5 6 non destructive stack print 7 DEPTH StackCellsUsed SP SO SWAP 2 FORTH DIMENSIONS III l 8 S prints stack contents top last stack unchanged 9 DEPTH IF SPA 2 SOQ2 DO I Z LOOP 10 ELSE Empty THEN 11 12 which vocabulary is being referenced 13 VOC prints CONTEXT VOCABULARY name 4 CONTEXTO 4 NAI 15 SCR 82 O Tools number printing fig FORTH 1 x 1 2 BASE prints current radix in decimal BASE DUP DECIMAL BASE create base specific stack print operators BASED lt BUILDS newBase DOES n g un Eu 7 BUILDS 8 DOES BASE SWAP BASE SWAP BASE 9 10 16 BASED H print top of stack in hex 11 8 BASED O print in octal 12 2 BASED B print in binary 13 14 15 The following utility indexes 10 screens at a time and is an excellent aid in searching HEX INDEX 113 O DO DUP 10 SWAP OVER INDEX KEY ESC IF LEAVE THEN LOOP The following utility was contributed by Sam Bassett and is an excellent program development aid that shows you what the current base is BASE BASE DUP DECI
48. ithin the 128 bytes of the dictionary a Full Stack error 7 is given STACK is not executed at runtime unless compiled by the programmer though it is executed frequently during compiling and text interpretation WORD A FORTH only This definition moves text from the current input buffer to the head of the dictionary The error test performed checks that there is enough space between the head of the dictionary and the top of the stack for the text about to be moved If there is not enough space a Dictionary Full error 2 is given This prevents the system from crashing by writing over its own stacks DO WE NEED IT Should we have all this security all the time Or just when we think we need it Fig FORTH currently does not give us a choice on the matter Sure we can com pile on top a new set of compiler direc tives which don t have the tests but we have then already wasted all the memory for the secure directives the XXX words and the lot The reverse course I con sider more appropriate The kernel system should have as little protection as pos sible The system should not suffer the overhead for those who do not desire it If security is desired a Novice Pro grammer Protection package could be Page 18 compiled into a user s area which would include all the words necessary to protect him or her and the other users from him or herself This would allow protection even for the words such as store FILL
49. lementation includes the normal read write block commands plus a number of new utility words The modification is available on ESF wafer for 14 95 includ ing shipping For more information contact Kalman Fejes KALTH MICROSYSTEMS P O Box 5457 Station F Ottawa Ontario K2C 3J1 Canada Page 32 How to form a FIG Chapter 1 You decide on a time and place for the first meeting in your area Allow about 8 weeks for steps 2 and 3 2 Send to FIG in San Carlos CA a meeting announcement on one side of 8 1 2 x 1l paper one copy is enough Also send list of ZIP numbers that you want mailed to use first three digits if it works for you 3 FIG will print address and mail to members with the ZIP s you want from San Carlos CA 4 When you ve had your first meeting with 5 or more attendees then FIG will provide you with names in your area You have to tell us when you have 5 or more Northern California 4th Sat FIG Monthly Meeting 1 00 p m at Southland Shopping Ctr Hayward CA FORML Workshop at 10 00 a m Southern California Los Angeles 4th Sat FIG Meeting 11 00 a m Allstate Savings 8800 So Sepulveda L A Call Phillip Wasson 213 649 1428 Orange County 3rd Sat FIG Meeting i2 00 noon Fullerton Savings 18020 Brockhorst Fountain Valley CA 714 896 2016 San Diego Thur FIG Meeting 12 00 noon Call Guy Kelly at 714 268 3100 x 4784 for site Page 33 Massachusetts 3r
50. len addr char DUP len addr char char OUCH len addr char OVER len addr char addr ci len addr l len addr 1 SWAP addr 1 len l addr 1 len 1 ELSE len addr char len addi char DROP len addr SWAP add len DROP addr 20 add 20 OUCH addi 0 addr 0 OVER addr 0 addr Cc addi 0 add 0 THEN addr 0 ELSE len addi char len addr char DROP len addr 8 len addr 8 OUCH len add 1 len addr 1 SWAP addi 1 len l addr 1 len 1 THEN addr 1 len l addr 1 len l OK HELP WANTED FORTH PROGRAMMER Entry Level Will Train John Sackis Data Breeze 2625 Butterfield Rd Suite 112E Oakbrook IL 60521 312 323 1564 FORTH DIMENSIONS III l CONDITIONALS The IF ELSE THEN construct automatically saves and restores the stack values A mismatch in number along the two paths produces a warning message STK ERROR ELSE m THEN n where m is the number of parameters left on the stack at the end of the IF clause and n is the number left when the THEN is encountered The DROP PUSH prompts are presented for the user to attempt recovery A known cause of this message is a DUP preceding the IF as this is not handled SPOOLING TO DISK To be useful a hard copy of the output without all the intermediate operator conversation is useful It is also quite possible that a machine readable version would be handy to facilitate distributi
51. machine is not in the execution state when EXEC executes an Executlon Only error 18 occurs If the machine is not in the compilation Page 17 state when COMP executes a Compilation Only Use in Definition error 17 occurs Tf the machine is not in a state of loading when LOADING is executed a Use Only When Loading error 22 occurs The testing of machine states as above is necessary when words such as BEGIN and AGAIN see example in STRUCTURE ERRORS above are used These words may only be compiled because they must compile something other than themselves which is not known at the time they are executed During compiling and similar operations there are only a few parameters which are actually checked In most cases the parameters checked are those involved in the other areas of compiler security or those which deal with the size or validity of the dictionary and stack The words involved in other compiler security areas are ICSP CSP PAIRS These words are used to protect against structural programming errors as described above in STRUCTURAL ERRORS An explanation of each of the uses of these words is as follows CSP CSP These words are used together to check for changes in the stack position CSP stores the current stack position in the user variable CSP 2CSP compares the value in CSP to the current stack position and if they are not the same issues a Definition Not Finished error 20
52. n the IFST Does not affect the parameter stack Marks the end of the spool file with a zero adr NUM cond Checks current word to determine whether it qualifies as a legal hexadecimal number CONSTANT A defining word which causes the name of the defined word to be put on the stack when that word is encountered a DEPTH depth Computes the depth of the stack in items scr DOC a Page 28 Searches for a colon followed by the word whose name follows this invocation on the specified screen It aborts if the definition is not on the specified screen Otherwise it commences to gen erate the diagram for the word specified ELSE ell el2 etc Clears the stack and then restores it from IFST ESC aos Aborts the package if an escape key was the first key pressed in answer to the PUSH prompt The vocabulary reverts to FORTH however the stack diagram package is still loaded and ready to go G HERE adr cond Moves a string from PAD into the dic tionary It allots the space and leaves the address of the item and a true cond if successful It leaves only a false cond if no valid string was found expr G 1 op expr Builds an expression from a simpler expression At execution time of the following word the top of the stack is enclosed in parenthesis and preceded by the operation symbol It is used for unary operations eg name expr G 2 oplexpr Similar to G 1 except that
53. n redefined to put their own name on the stack Before this facility was added I always retyped the variable name manually when it came up The spool function and some of the source reading routines such DOC assume that screen blocks are contiguous 1 024 byte areas Those functions using BLOCK will have to be rewritten if this is not the case in your system I recommend that you instead generate a new system with lk buffers as that is faster and more flexible WEAKNESSES AND PROPOSED FUTURE EXTENSIONS The diagrammer presently does not keep track of the contents of the return stack This requires uses of R and I go to the operator for clarification Try a pencil for now This could be added in a similar fashion as IF ELSE THEN by an additional stack The area of error recovery is ripe for suggestions Perhaps some dummy buffer area could be added and tested in PSTAK This would allow detection prior to destruction on stack underflow Backing up by reading backwards would be nice but also very difficult to implement CONCLUSION Now that the tool has been built its real function is more evident Tt 18 still used for documenting words as origi nally intended however its primary usage is debugging and validating code It has also proved to be very useful as a teaching aid to explain what is going on within the stack I hope it will be as useful to you as it has been to me A STACK DIAGRAM GLOSSARY VARIABLES BK The
54. ndex 52 MY ARRAY ZERO ORIGIN This would take data from the top of the parameter stack and store it in MY ARRAY Alternatively one would access an integer from this array by 27 MY ARRAY The disadvantage of arrays is that they require both an explicit index and an explicit load or store operator While an array could be used for temporary storage of parameter stack data such programming practice is not neccessarily clear or efficient So how does a user stack help us Consider the integer user stack defined 100 STACK MY STACK MY STACK would in this case have a size of 100 integer elements Data can be put into this user stack from the top of the parameter stack by gm H n pPPo PM M Q PB eP M M 4nM U P QP M M Q J s X e Q T Q Po MP D Pace 20 PUSH MY STACK while it can be retrieved back to the parameter stack by POP MY STACK Note that addressing is implicit there are no indices and that the direction of data transfer is set by the PUSH and POP words USER STACK WORDS types of user stacks STACK DSTACK and In practice three have proved useful FSTACK While stack variables created by these three defining words ali use the PUSH and POP words to save and retrieve data the amount or type of data pushed or po
55. nition have been completed Since the above error checking leaves data on the stack if a structure has not been completed the simplest check is that of the stack position When a definition is entered colon stores the Current Stack Position in the user variable CSP At the end of a defini tion semi colon executes CSP to compare the current stack position to the value stored in CSP If the values differ a Definition Not Finished error 20 occurs indicating that either data was left on the stack or that too much data was removed from the stack i e that a programming structure was probably not completed The word probably is used here because other conditions such as the improper or sometimes various proper uses of the word LITERAL will cause the same error condition to occur MACHINE STATE ERRORS The loading and execution of a FORTH program causes the system to enter several different machine states Three of these are loading compiling and executing Each of these states is defined by its own set of parameters and some states may even overlap For example while loading a screen off the disk the machine will be either executing or compiling Here the loading state has overlapped with either the execution or compilation state The machine cannot be in the execution state and the compilation state at the same time though the states may be inter leaved An example of interleaved states is the use inside a defini
56. nts would do this If a correct representation is not possi ble the result should be nearer zero Dave Boulton is more know ledgeable on this point Sign is to be used within lt and gt The user chooses where to store the sign Notice that no word gener ates the saving of the sign In fig FORTH the only difference is the ROT would be explicitly done just before SIGN rather than in SIGN FIG and the Europeans make an imme diate word for error control Other users and FORTH Inc reject this level of error control too bad We need a technical paper presenting the trade offs code needed and compila tion slowdown Conversation at a team meeting is insufficient to change opinions developed over ten years These topics were barely touched on by the Team as CODE definitions are not portable CODE probably should FORTH DIMENSIONS 111 1 TR A m SS terminate in END CODE This is an unresolved area The standard wording was painstaking ly done regarding vocabularies This is the most divergent topic among users all known methods can comply with the Standard but it does less than all systems The rationale is that you build CURRENT but you exe cute only from CONTEXT and FORTH No chaining is recognized beyond context leading to FORTH This may be physical links or logical within FIND Again position papers are essential to get a common more advanced construct Charles Moore has used
57. on of the documentations A spool file is generated to satisfy these requirements It may later be displayed or printed by PDOC The spool file contains the encoded screen from which the diagram was made followed by variable length lines separated by carriage return characters The file is terminated by an ascii null character It resides on a set of consecutive screens The first screen and maximum number are determined by literals in SPIT and PRTDOC I use 10 screens starting at 230 These may be copied elsewhere and printed by PRTDOC Failure to copy them will cause the listing to be lost the next time a function or screen is diagrammed IMPLEMENTATION PROBLEMS AND SOLUTIONS It is important not to search the standard vocabularies when diagramming stacks This is because actions are different for the same name depending upon state By way of example for the operator must concatenate the symbolic name strings representing these elements FORTH DIMENSIONS 111 1 with an embedded plus sign rather than adding the top two elements on the stack Also not all operators are defined On detection of this case the diagrammer must shift control to the operator prompt section In polyFORTH this was accomplished by defining a new vocabulary and having it be the only one searched in fig FORTH this option is not directly available since the FORTH vocabulary is searched after the current vocabulary This may be solved by carefully b
58. or just some of it and a programmer protec tion package Or maybe there is a better alternative Your input is wanted and needed Write to the 8080 group at FIG PO Box 1105 San Carlos CA 94070 and tell us what you think Page 19 NEW PRODUCTS POLYMORPHIC FORTH NOW AVAILABLE FORTH is now available for the Poly Morphic Systems SSSD 5 systems 8813 amp 8810 The PolyMorphic disk operating system has been patched in and the system is interfaced to the PolyMorphic operating system PolyMorphic FORTH includes a modified systems disk and brief documen tation on changes to interface to the PolyMorphic SSSD 5 disk operating system based on 8080 Fig FORTH Price is 50 00 For more information contact Ralph E Kenyon Jr ABSTRACT SYSTEMS ETC 145 103 S Budding Avenue Virginia Beach VA 23452 FORTH FOR HP83 HP85 A disk based FORTH is now available for the HP85 HP83 personal computers The implementation is the FIG FORTH 1978 standard with some machine dependent util ities User receives both 16k and 32k versions with user space being 2k and 18k respectively Both versions require a disk Included is an assembler a FORTH decompiler and editor This is not an HP supported product but available through the user s library FORTH in object form no source an assembler decompiler and editor in source are sent on a disk This product recommended for experienced users only Those familiar with FORTH should have no
59. ore to do custom program ming and provide extensibility Terminals up to two miles away can be polled at a rate 30 times faster than the previous protocol which was written in assem bler Dean Sanderson was the principal programmer on the project The famous 200 Hale Telescope at Mt Palomar Observatory near San Diego has recently installed a polyFORTH system for data acquisition and analysis using a PDP11 44 and a Grinnell display proces sor The Observatory has been using FORTH since the early 1970 s including a miniFORTH system installed in 1975 and an early polyFORTH installed in the late 70 s Barbara Zimmerman a programmer at Cal Tech which operates the observatory said I am extremely impressed by the level of polish and sophistication in polyFORTH and the performance of this system is outstanding The type of work done involves reading data from an 800 x 800 array of CCD sensors integrating and recording the data and displaying it in the Grinnell Charles Moore installed the system which features a comprehensive math package for analysis as well as basic image processing functions A by product of this installation is the availability of polyFORTH in RKO5 disk cartridges These are available with on site installation SCHEDULE OF UPCOMING FORTH INC SEMINARS AND WORKSHOPS Location Seminar Workshop Palo Alto June 4 June 5 Houston July 7 July 8 Tampa July 9 July 8 Irvine July 23 July 24 FORTH DIM
60. pped differs As discussed earlier STACK deals with integer two byte words DSTACK consists of elements of double precision integer words four bytes while FSTACK elements are floating point numbers six bytes All three of these words are defined in terms of an arbitrary n precision NSTACK word which allows specification of any number of two byte words per stack element Two other words are also useful with user stacks There are EMPTY STACK and STACK Note that both of these cannot presently be used within colon definitions The line EMPTY STACK MY STACK will for example reset the stack pointer for the user stack MY STACK so that it will be empty Again using the MY STACK example STACK MY STACK will dump out the contents of the stack from the top of the stack through the bottom of the stack STACK is intended purely as an aid in debugging IMPLEMENTATION As was previously mentioned STACK DSTACK and FSTACK are all defined in Page 21 INCREASING MEMORY ADDRESSED of a more general NSTACK defining A line such as terms word 22 4 NSTACK WIDE STACK will define a 22 element stack with eight bytes four words per element NSTACK has two primary parts The first part executed when a new stack is defined builds a FORTH word header stores some stack definition parameters into the dic tionary and finally allocates the actual dictionary space for the stack The second part written
61. r INCH DROP PUSH VALUE char PUSH VALUE INCH len addr char DUP len addr char char 7F len addr char char 7F len addr char char 7F IF len addr char DUP len addr char char 0D len addr char char 0D len addr char char 0D IF len addr char DUP len addr char char OUCH DROP 1 PUSH VALUE Page 24 FIGURE 1 cont OUCH len addr char OVER len addr char addr Ci len addr 1 len addr 1 SWAP addr 1 len l addr 1 len 1 ELSE len addr char len addr char DROP len addr SWAP addr len DROP addr 20 addr 20 OUCH DROP 1 PUSH VALUE OUCH addr 0 addr 0 OVER addr 0 addr al addr 0 addr 0 THEN addr 0 ELSE len addr char len addr char DROP len addr 8 len addr 8 OUCH DROP 1 PUSH VALUE OUCH len addr l len addr 1 SWAP addr 1 len 1 addr 1 len 1 THEN addr 1 len 1 addr 1 len l OK FIGURE 2 OK 100 LIST SCR 100 1 ANALYZE SWAP INCH DUP 7F IF DUP OD IF 2 DUP OUCH OVER C l SWAP l 3 ELSE CR DROP SWAP DROP 20 OUCH O OVER C O THEN ELSE DELETE DROP 8 OUCH 1 SWAP 1 THEN t OK Page 25 FIGURE 3 PDOC STACK DIAGRAM SCREEN 4 100 ANALYZE addr len SWAP len addr INCH len addr char DUP len addr char char 7F len add char char JF len addi char chat 7F IF len add char DUP len addr char char 0D len add char char OD len addr char char 0D IF
62. reaking links with zero entries or alternatively by defining a special dictionary search routine that stops at some fence value I chose the latter Lt wasn t obvious until the implementation began that operators would require concatenation of their identifying strings It was also decided that parenthesis would be placed around each level of expression nesting so that ambiguity could be eliminated without rearranging expressions for precedence This occasionally leads to expression such as array 2 2 This is unavoidable since even the constants within the expression are treated as strings rather than numbers Thus the example cannot be reduced to array 4 Error recovery is not nearly as good as I d like it to be Stack underflow in the diagramming session is generally fatal Due to the amount of bookkeeping already being done there is no provision for retracting answers after wrong data has been put on the diagram stack This is inconvenient in a first pass through a function but has not proved to be a problem once a feel for the tool and the function being diagrammed has been acquired Provision is left for user defined functions in the last two screens of the diagram source This allows commonly used functions to be handled in an automated fashion This makes it very easy to define composite functions such as l as the sum of its component parts For out side of functions constant and variable Page 26 have bee
63. rs I have yet to use the JMP indirect after finding out about its shortcoming of wrapping around within a page if low byte of address is FF I pretend this opcode does not exist Editor CREATE on 6502 systems correctly Page 9 places code field Anymore comments should be directed to Chuck Peddle designer of 6502 Keep up the good work Edward B Ted Beach 5112 Williamsburg Blvd Arlington VA 22207 CORRECTION ON SEARCH by John James Vol IL 6 When you are debugging or modifying a program it is often important to search the whole program text or a range of it for a given string e g an operation name The SEARCH operation given below does this To use SEARCH you need to have the FIG editor running already This is because SEARCH uses some of the editor operations in its own definition The SEARCH source code fits easily into a single screen it is so short because it uses the already defined editing func tions Incidently the FIG editor is documented and listed in the back of FIG s Installation Manual Use the editor to store the source code of SEARCH onto a screen Then when you need to search load the screen Of course if you are using a proprietary version of FORTH it may have an editor and search function built in and auto matically available when needed This article ette is mainly for FORTH users whose systems are the ten dollar type it in yourself variety Here is
64. stack to finish the structure and compilation continues on to the next word Below is a table of the conditional pairs for the current structural compiler directives with the values placed on the stack open and the values removed from the stack in parenthesis Note that UNTIL and END as well as THEN and ENDIF have the same effect Only the former of each pair are presented here for clarity BEGIN 1 UNTIL 1 BEGIN WHILE 4 BEGIN 1 AGAIN 1 REPEAT 1 4 IF 3 THEN 2 IF 2 ELSE 2 2 THEN 2 DO 3 LOOP 3 DO 3 LOOP 3 DO 3 LOOP 3 DO 3 LOOP 3 FORTH DIMENSIONS III l Note that ELSE tests and replaces the same value on the stack Because of this the current compiler security system cannot detect the presence of multiple ELSEs in a definition For example in the definition ELSE EXAMPIE flag true or false message IF True part 1 ELSE False part 1 ELSE False part 2 ELSE False part 3 THEN if compiled and it will compile and then executed with a boolean value zero or non zero on the stack will execute without crashing the system But the execution may not be what you expected If entered with a true flag non zero the True Part 1 and the False Part 2 will print while if entered with a false flag zero the False Part 1 and False part 3 messages will print To borrow a phrase from Kim Harris probably Not what you had in mind zu This is the only case I know of wh
65. th Fig FORTH Ail words in the Fig model including disk support work correctly Portability to other machines is also claimed Stand alone Fig FORTH for OSI is avail able on one 5 1 4 disk for Cl Super board C2 and C4 machines with 24K Product includes a structured 6502 macro assembler and disk utilities designed by FORTH Tools and the FIG portable line editor Complete technical documentation and the fig FORTH glossary are also included The complete price is 49 95 For more information contact FORTH Tools Box 12054 Seattle WA 98102 DEA EDI I AM AFR THA THE LLT IN THE LAS ISS ABO SOR INC USI ONL THR LET NAM FIE HAS HAD THE OPP EFPT FRO wHA THE WaAl WAN SiS LET LIZ THA THR LET AND U iS J ARI o TER OF A TRA OFF BZT t KEE LEG WE STI DON SEE THE NEE FOR 31 CHA NAM Y THE GEN CAS YOU TRU CHU MOO POR INC P S MR FRE THO IS XOT AN EMP OF FOR INC Page 23 A STACK DIAGRAM UTILITY Barry A Cole 3450 Sawtelle Blvd 332 Los Angeles CA 90066 INTRODUCTION AND CONCEPT A year and a half ago when I was still fairly new to FORTH I spent a lot of time drawing pictures of stacks as I made up programs I crumpled them up and started over each time I changed them As sections were debugged I drew up another copy to document the code When I found an error I would have to redra
66. tion of a pro gram segment similar to this Page 16 SCREEN 3C0 LITERAL which temporarily suspends compilation to calculate the value within the brackets and then compiles it as a sixteen 16 bit literal Remember though that to com pile the machine is executing a program and that compiler directives such as LITERAL above execute during compilation to perform their task but the machine state remains that of compilation Certain words require that the machine be in a specific state to execute proper ly These words are programmed to contain one of the following words COMP EXEC LOADING which check for their corresponding state and issue an error message if the machine is not in that state Below is a descrip tion of each of the above words and the parameters which determine the current machine state EXEC or COMP The execution state or compilation state is determined by the value of the user variable STATE which has a zero 0 value if the machine is in the execution state and a non zero value the machine is in the compilation state LOADING Loading is determined when the value of the user variable BLK has a non zero value A value of zero for BLK indi cates that input is coming from the user s terminal and that the machine is therefore not loading The above words are defined as follows EXEC STATE 18 ERROR COMP STATE O 17 ERROR LOADING BLK Q9 Oz 22 ERROR LI LI i If the
67. tion supplied with the system is a 68 page booklet USER S MANUAL amp TUTORIAL It is a very well done manual introducing users to the systems and to the FORTH language However source listings are not provided My overall impresssion was that this is a well rounded FORTH system suitable for engineering and professional applications Editors Comment FORTH Dimensions refrains from publishing timing benchmarks as this reflects processor speed more than effectiveness of problem solving How ever the above review points out that the allegedly superior Z 80 runs these tests slower than the 8080 Our point is that the user should evaluate all aspects of problem solving hardware characteris tics language implementation and appli cation technique The Timin manual is sold separatly for 20 00 This price is not justified by the copy received for our evaluation HELP WANTED FORTH PROGRAMMER PDP 11 RSX Op Sys On Site Contractor Micro Temps 790 Lucerne Dr Sunnyvale CA 94086 408 738 4100 STEWARD WHAT F NOU MEAN KIND OF AIRPLANE 1 A DEE CEE I THIS R ONE ZERO FORTH DIMENSIONS III 1 FORTH TELE CONFERENCE IS NOW OPERATIONAL FORTH now has a dynamic public access data base By dialing into the FIG CommuniTree tm the CommuniTree Group you may access our tele conferencing system It was created by Figger John James to allow group interaction to build upon our collective knowle
68. trouble using this system i e there is no manual inluded However sufficient references are civen Current cost is 50 00 For more information contact Nany Reddington at 503 757 3003 FORTH PROGRAMMER AVAILABLE 3 mos experience with FORTH also know BASIC amp COBOL Active member of F I G Contact Martin Schaaf PO Box 1001 Daly City CA 94017 415 992 4784 FORTH DIMENSIONS 111 1 USERSTACK Peter H Helmers University of Rochester Department of Radiology Medical Center Box 648 Rochester NY 14642 INTRODUCTION One of the advantages of FORTH is its use of a stack oriented architecture In conventional FORTH implementations one has available two kinds of stacks the return stack and the parameter stack In general the return stack is used to keep track at execution time of the path of invocation of nested FORTH words while the parameter stack is used to manipulate data used within and or passed between FORTH words Unfortunately in the real world such a clean segmentation between parameter data and execution nesting data tends to break down For example DO LOOPs are imple mented by using the return stack to keep track of the loop count and associated data The motivation for this violation of the sanctity of the return stack with DO LOOP parameters is the desire to separate the DO LOOP data from any parameters being used by the programmer within the loop Failure to do so would allow conf
69. unary operation is also enclosed within the parenthesis eg name 2 espr G 3 op expr Similar to G 1 except that binary operation is also enclosed within the parenthesis eg vall val2 inadr GBLD An auxiliary word used to build a named string in the dictionary from the word following GBLD This is used at Page 29 compile time of the stack diagram package GWRD A defining word for building strings into the dictionary at compile time of the stack package On invocation of the new word the address of the string displaying its own name is put on the stack The word that follows GWRD is read twice at compile time once for the name of the function and a second time to be placed in string format into the dictionary This is used to build up constant words for the diagramming package cond IF Drops the condition flag from the top of the stack without evaluating it It then invokes SAV for ELSE restoration and THEN error checking adr cnt MTYP Types the message to the screen and also passes the parameters to STYP for spooling src dst len MVB dst len src l src Intermediate function to set up for MVDEL src dst delim MVDEL adr Move a string from the source to the destination address until the specified delimiter is encountered This is used to build data strings within the dictionary PDOC ao Prints the latest generated diagram from the default spool file blocks PHDG Prints t
70. usion of loop parameters with actual user data causing a consequent abnormal execution of the DO LOOP arising from an unwarranted modification of loop parameters In addition to the above saving of DO LOOP parameters on the return stack it is not uncommon practice for a program mer to want to save some parameter stack data in order to be able to first calcu late using data beneath it One previous ly employed method to do this was to temporarily push the parameter stack data onto the return stack and then later Editor s Note Mr Helmers uses URTH a dialect of FORTH FORTH DIMENSIONS III 1 retrieve it when subsequently needed Admittedly this is an easy lazy way to achieve tranisent data storage But woe unto those who forgot to pop the return stack of this temporary data USER STACKS The user stack concept allows a FORTH program to retain the convenience of an auxiliary stack but in such a way as to avoid mixing temporary data with execution time return information As an added convenience this concept allows creation of multiple named stacks which can be typed according to the number of two byte words per stack element A user stack can be thought of as an array integer double precision or real of data which has implicit addressing Consider by way of analogy a conven tional array such as 100 DIM MY ARRAY One would store the 53rd integer element by explicitly stating the i
71. uter Faire Material should be sent in no later then 1 September 1981 please send them early and give me a chance to get ahead I will distribute the draft for review and testing by 15 October 1981 Finally I will begin compiling the final version by 1 January 1982 and have it ready for publication by 1 February 1982 This may seem like a long time abuilding but I want to provide ample opportunity for the contribu tors to develop their ideas fully and conduct a fair amount of testing themselves before submission I also want to provide a good review by the committee to provide the highest quality document for FIG It will be worth it in the long run Your con tributions will be sincerely appre Ciated and though the publication as are all of FIG s will be in the public domain credit will be given to the authors and contributors So if nothing else this is a chance to get your name in print in an inter national publication Sincerely George O Young III 617 Mark NE Albuquerque NM 387123 FORTH DIMENSIONS 111 1 Eri i 1 This is a great project Our goals continue to be to decentralize FIG activities and George s project of a published Goodies Package wiil be helpful to all Contributors should send a brief description to George and then prepare the full document This will allow co ordination of similar material ed IH wr aesr SC OBADUS Y FE HTK os HNL oy ANTEREST GROUP Spreading t
72. w whole series of stacks just as a cartoonist would have to change a whole series of frames It soon became clear that I was expending time to do rather tedious work I came up with an idea for an automated tool to update these diagrams I thought up a way to represent the stack data easily and an approach to implement the tool The original implementation was done in 8080 polyFORTH by my co worker Greg Toussaint We collaborated in the initial debugging and then passed it back and forth over the next four months After nearly a year in active use I converted it to fig FORTH and updated several messy areas to be more straight forward The results of these pursuits are detailed in this paper for more general consumption ORIGINAL IMPLEMENTATION The original program was going to take push and pop information from the keyboard to generate pictures of what was on the stack It became immediately clear that the stack could more easily be represented horizontally than down the page We chose to put the stack to the right so that the size of the stack could be read like a bar graph I figured that if I represented each item on the stack as an address pointing to a count and printable string that many of the stack diagram words would be identical to the FORTH word eguiva lent Thus DUP OVER DROP as well as many other primitives would be coded before I started Even as it was being FORTH DIMENSIONS 111 1 built the tool grew to
73. will detract from the clarity of the final output The program will then continue reading words from the source screen and generating output lines to the console and spool file In a typical sequence up to about a dozen lines will be handled without inter vention For example occurences of DUP DROP and numeric literals will be pro cessed automatically When a is encoun FORTH DIMENSIONS III l tered it will revert to the prompts since it is not known what a symbolically appro priate name is for the fetched value Processing will terminate with an OK for sucessful completion of the screen or colon for SDOC or PDOC respectively If stack underflow occures it will abort It is good practice to do a FORTH after an abort condition to insure that the stack vocabulary is properly exited A user abort is also provided This is accom plished by typing an escape key followed by a carriage return in response to the PUSH VALUE prompt SAMPLE DIALOG The package creates a special stack vocabulary as well as the user entry points The use of the package is best seen by example Figure 1 is a sample dialog Notice how little intervention is required and how the ELSE restores the stack values Figure 2 is the source that was used in the examples Figure 3 is the printer output as displayed by PDOC FIGURE 1 100 spoc ANALYZE DROP PUSH VALUE addr PUSH VALUE len PUSH VALUE ANALYZE addr len SWAP len add

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