Trs8bit - FabsitesUK.com
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1. 10 cpi bi directional N Y N N N N Y print head life chars 150 million 50 100 million 200 million n a 30 million n a descenders Y Y N Y N N Y no of wires in head 9 9 9 n a n a 7 n a densities chars line 40 66 80 132 40 66 80 132 40 80 132 40 80 9 18 cpi 40 80 5 8 5 10 12 17 graphics N Y Y Y Y Y Y slash zero N N Y Y Y Y N line spacing Lines per inch 6 6 or 8 6 or 8 software selectable 6 6 9 variable fwd amp rev max paper width 9 5 fanfold 8 5 cut 10 fanfold 9 5 fanfold 8 5 cut 4 5 2 38 ins fixed 9 5 fanfold 8 ins tractor or friction feed F T Both F F T F max copies 3 3 3 1 1 1 1 ink ribbon mobius loop ribbon cartridge ribbon 5 typewriter 4 colour pens Aluminum coated inked roller cassette bubble jet cartridge TRS8BIT vol 02 no 03 september 2008 page 7 o0o Continued from page 2 For those of you who visit the web site on a regular basis you ll already know I ve put out a request for help on an article to convert a program from apple ii basic to level ii basic It is supposed to produce a sudoku puzzle on a 9 x 9 grid I just thought that producing sudokus on a level 2 model 1 would be just amazing and make a great novelty idea for the Christmas edition Which by the way should be available early December 2008 I also won on ebay a dpm 100 print2. Recently i received a call from a man who needed to know how many tracks and heads were on a Radio Shack 70 Meg hard drive Such a simple request and completely necessary in order to partition and format a hard drive But where do you find the information when you need it at 1 AM The answer should be in the Radio Shack hard drive manuals but it is only presented in a fragmentary and incomplete fashion unless you have the Service Manual for that particular drive If you are doing a drive swap like hot rodders used to swap engines forget it Radio Shack doesn t even want to talk to you This article will provide a quick summary of the pertinent factors for the various drives Radio Shack has used in our TRS hard drive packages I will exclude the 8 4 Meg drive as that drive is not suitable for the Model 1 111 and 4 family Model 1 3 and 4 drives I will include a few other drives which you may run into To begin with all drives suitable for use with Radio Shack controllers are categorised as MFM meaning modified frequency modulation and have the same interface as the Seagate ST 412 or Seagate ST 506 drives This interface physically consists of two card edge connectors one with 20 conductors the other with 34 plus a 4 wire male power cable connector Usable drives in this category range from 5 to 70 Megs The maximum head count and cylinder count which can be use by the Radio Shack hard drive controller
3. between pins 8 and 9 of z37 a solder sucker is need here close to pins 9 and 10 of z73 pin 10 on the component side and pin 5 of z74 note some late issue boards also have the traces of pins 12 13 and 14 of z73 joined together so the trace both sides of pin 13 must also be cut using thin insulated wire connect these pins in this order from z73 pin 11 to z74 pin 10 from z73 pin 12 to z73 pin 5 from z73 pin 10 to z73 pin 4 and on to z51 pin 13 from z73 pin 13 to z37 pin 10 from z73 pin 9 to z51 pin 14 and on to z21 pin 15 from z73 pin 8 to z37 pin 9 from z74 pin 5 to z36 pin 4 from z37 pin 8 to z37 pin 7 now x3 has to be modified as mentioned earlier starting from pin 1 leave that as is pins 2 3 4 and 5 have to be open and pins 6 7 and 8 closed a small screwdriver can be used to open and a blob of solder to close as needed before the 16k ram chips are removed the system can be tested by switching the computer on in level 2 mode and entering print mem the answer should be either 48340 or 48338 depending on which type of roms are fitted the figures are only 2 reflections of the existing 16k and as such cannot be used providing the system works this far then fitting the 64k rams can be carried out remove the 16k rams and put them safely away with the keyboard still laid out with the keys away from you cut the 12v trace at pin 8 of z19 cut the 5v trace at the capacitor pin below
4. both machines are configured as data terminal equipments dte and although you can reverse pins 2 and 3 on the rs 232 board in the model 1 the other signals will be trying to output to one another this should not result in any damage but will prevent proper hand shaking between the systems you will need what is termed a null modem connector with all the signal crossed over these can be obtained at many local computer supply shops or you can easily make one for yourself see the article on page 3 ed assuming you have a smart terminal program like st80 iii on the model 1 you set the system up for 300 baud 7 data bits even parity 1 stop bit transmit auto line feed on and receive TRS8BIT vol 02 no 01 MARCH 2008 page 6 auto line feed on on the model 100 select telecom from the main menu then set the rs 232 parameters using f3 stat 37e1e now use f4 to get into terminal mode keys pressed on the model 1 should be echoed on the model 100 and vice versa showing that all connections on both systems are functioning if you are transferring a file from the model 1 to the model 100 you now get the file into the model 1 buffer using shift g respond to the transmission speed question with 1 to be on the safe side on the model 100 use f2 to select the download mode the system will request a filename after inputting the filename f2 will be displayed in reverse video now press shift
5. but a short article for trs8bit telling us how well or otherwise the mods went would be most appreciated Also While I m thinking about freebies I ve once again thanks to ebay acquired a number of new old stock ribbons for an Epson lx80 if you re having trouble sourcing a replacement just let me know The reference numbers quoted are 8mm x 6m F35703za And while helping on a clearance I came across a TRS8BIT vol 02 no 03 september 2008 page 2 pc 6 computer any time I need a conversion figure here s a few old chestnuts but just in case you don t have them to hand to disable the model 1 s break key poke 16396 23 and just as handy to enable the break key poke 16396 201 if you can t remember what you ve set memory size to when starting level ii basic here s an easy way to help printpeek 16561 peek 16562 256 2 If peek 293 73 the machine you re on is a model 3 any other value and it s a model 1 these work fine with matthew reed s m1 emulator if you re on a model 1 Poke 15360 1 Print peek 15360 this will print a 1 if the r s lower case mod had been fitted If not the result will be 65 There s a little buglett in some editions of trs dos 2 3 which I had forgotten about the password protection gives up after one try The first time you try to copy an uncopyable file it will give the error message file access denied Try to copy it again this
6. o on the model 1 keyboard and the file will be transferred from the model 1 to the model 100 being simultaneously displayed on the model 1 and model 100 screens when the file has been transferred st80 iii ready will be displayed on the model 1 if you press f2 on the model 100 the file will be closed and you can exit from telecom by pressing f8 twice to upload from the model 100 to the model 1 first set the model1 up for receive auto line feed on shift b and open the memory buffer shift c keying f3 on the model 100 will result in the request for the file name input the file name and respond to the width question with enter up will be displayed in reverse video and the file will be transferred to the model 1 being displayed on the model 1 screen as transfer occurs when the file has been transferred up on the model 100 screen will change from reverse video to normal Keying shift x on the model 1 will close the memory buffer and the file can be transferred to disk using shift f This program is one of the most useful ones I ve ever had for a 16k model 1 it will actually fit down to a one liner It s a super little lower case driver It worked well subject to any necessary hardware mod being completed with ordinary level ii basic aculab xbas disk basic and more recently matthew reeds emulator The really nice thing about it was that it works in reverse i e with the
7. these 11 34 and 67 Meg drives It is not possible to use any drive larger than 67 70 Megs because the HDC cannot deal with more than 8 heads and 1024 cylinders and the DOS cannot handle other than 32 sectors of 256 bytes each No matter the 67 Meg is a large drive and you are unlikely to fill it Slave drives I have omitted discussing slave drives in this article The whole point of swapping drives is to get more capacity and my feeling is that you are better off to put a big drive in the master and file the slave in the closet You can go as large as 70 Meg in your master so why fool around with the slave drive Just in passing I will remark that the three wires are actually four in number in a slave box TRS8BIT vol 02 no 02 june 2008 page 7 the fourth wire bringing 12 volts to a power relay which obviates the need for a power switch in a slave and the wire colours differ from those in a master box Miscellaneous comments A few other factors of interest are the sector interleave the cylinder to reduce write current the cylinder to begin pre compensation and the average access time The sector interleave is predetermined within the formatter and unless you are good at machine code is not adjustable The gurus who designed the Radio Shack hard drive system set this for us I have not made any attempt to tune the interleave having not had the time nor the interest to tack
8. TRS8BIT vol 02 no 01 MARCH 2008 page 1 Trs8bit Welcome to this the first edition of 2008 thanks for taking the time to download and read it Don t forget that the newsletter format is designed to produce an a4 booklet when printed I find that an a5 sized booklet is much easier to hold and read I hope that once again I ve managed to find interesting items to cater for a selection of tastes and interests The model 1 does seem to dominate but never having owned any other trs 80 I m a bit in the dark with the later model 3 s and 4 s If there is any subject you wish to be featured please email me with suggestions and I ll do my best to oblige I ve noticed on ebay over the last 6 to 8 weeks 2 video genies 3 model 100 2 s and various model 4 come up for sale I was surprised at how little they fetched One of the genies a model 3003 went for just under 40 one of the model 100 only fetched 99p and a model 4p only managed just over 15 Whilst rummaging through my bit and pieces I came across items for both the model 100 and the video genie this lead me to discover another interesting web site in new Zealand I ve put a link to this on trs 80 org uk This edition includes an article by ken Robinson which lists details of the genie s 50 way bus as matched to the model 1 s 40 way bus Knutt has various pieces of genie information on his web site It s well w
9. for saying may is that the white wire also enters into the picture The white wire senses seek completed which is a signal returned by the drive to the HDC While the drive is actively stepping this line will be at 5 volts signifying seek is not complete When seek is complete the line goes low and the white wire will be at 0 volts The white and yellow wires are NORed to turn on the green light when TRS8BIT vol 02 no 02 june 2008 page 5 both are low If the drive is stepping or not selected the green light goes dark Thus the steady green light means the drive is selected and is not stepping and a flickering green light means either the drive is stepping or is momentarily not selected as the DOS checks on a floppy drive or does something else Normally the green light is lit on the master drive If you have a slave connected its green light will normally be dark The orange wire is part of the Write Protect circuit and sends 5 or 0 volts to the HDC thereby informing the logic whether the WP switch on the front of the case is depressed When the switch is depressed and the red light is on the orange wire is at 0 volts When the WP light is off the orange wire is at 5 volts A cautionary note on a quirk of the write protect circuit is appropriate The red lamp is active in a sense even when it is dark When the lamp is dark 5 volts is passed through it to the remaining l
10. give us the address of somewhere different in memory where the string is located this address is stored in the usual z80 format of least significant byte first followed by the most significant byte if we wanted to be bullet proof then we ought to include a test on whether or not the varptr supplied from basic belongs to a string or some other variable this we could do by looking three bytes before the size and checking that the value there is three if not the varptr belongs to something other than a string once we have checked that the size isn t zero and the actual TRS8BIT vol 02 no 04 Christmas 2008 page 4 address has been loaded into the d and e registers then we go round a simple loop looping the a register with each character in turn checking if it is outside the range a to z and if not then re setting bit 5 to zero by and ing with 5fh putting the result back where we found it on completion we simply ret urn to basic to get this routine within a basic program we convert all of the bytes into decimal numbers eg cd 12 16 13 7f 7 16 15 etc and writing them into data statements but as this system of putting them back into memory requires an even number of bytes we must add a zero at the end giving 28 bytes in total we are going to store them in an integer array where each value in the array holds 2 bytes so for 28 we need to dimension 13 as we will use the zero one to ge
11. prompt which I ve been playing around with I ve produced a chart of look at a glance printer information to assist in checking for comparable options There s an article by anon who doesn t like mod Perhaps in his younger life he was a rocker eh Star billing goes to a cracking article by ec Kilpatrick for all you hardware buffs or anyone wanting to fit 48k inside their keyboard This all came about because I won some 8 bit 64k ram chips which were for sale on ebay and I was sure that in the back of my mind there was an article which had a use them Sure enough I found it It was originally published in natgug news in September 1984 and I ve managed to incorporate all the later additional amendments that went with it The chips are marked Sharp LH2164 15 now if anyone would like to try it out I d be more than happy to send the ram chips for you to use If you re interested please email me with your details and I ll send the chips off to you This looks to me like major surgery and is way past my meagre diy abilities I can t even guarantee that the chips are suitable or even still usable but it would be real fun to try it out Just think of it hardware mods on a 30 year old micro computer I don t recommend attacking your one and only remaining model 1 though N b this offer is by its very nature on a first come first served basis There would be no charge
12. shift held down lower case letters are produced This avoided accidental lower case entries A real boon for program development and de bugging o0o TRS8BIT vol 02 no 01 MARCH 2008 page 7 CONVERT WRITTEN BY LEOR ZOLMAN THIS PROGRAM CONVERTS REGULAR C SOURCE FILES INTO A FORMAT SUITABLE FOR EDITING ON THE TRS 80 OR ANY UPPER CASE ONLY SYSTEM SINCE THERE ARE QUITE A FEW ASCII CHARACTERS THAT NEED TO BE REPRESENTED EVEN THOUGH THEY DON T SHOW UP ON UPPER CASE ONLY SYSTEMS A SPECIAL NOTATION HAS BEEN CREATED FOR REPRESENTING THESE CHARACTERS THE POUND SIGN IS USED AS A SORT OF SHIFT KEY WITH THE LETTER FOLLOWING THE POUND SIGN DENOTING THE SPECIAL CHARACTER NEEDED NOTE THAT THE C COMPILER DOES NOT RECOGNIZE THIS SPECIAL SCHEME AND BEFORE YOU CAN COMPILE A SOURCE FILE CONTAINING THE SPECIAL CODES YOU MUST PREPROCESS THE FILE USING THE CC0T COMMAND THE SPECIAL CODES AND THE CHARACTERS THEY REPRESENT ARE L LEFT BRACKET FOR SUBSCRIPTING 5B HEX R RIGHT BRACKET 5D HEX C CIRCUMFLEX BITWISE NOT 7E HEX H UP ARROW EXCLUSIVE OR OPERATOR 5E HEX V VERTICAL VAR LOGICAL AND BITWISE OR 7C HEX B BACKSLASH FOR ESCAPE SEQUENCES 5C HEX U UNDERSCORE 5F HEX FOR EXAMPLE THE COMMAND A gt CONVERT FOO C BAR CT WILL EXPECT FOO C TO BE A NORMAL C SOURCE FILE ON DISK AND WILL CONVERT IT INTO A FILE NAMED BAR CT THE FILE BAR CT MAY THEN BE EDITED TO YOUR TASTE BUT REMEMBER TO PREPRO
13. the location in memory where the asterisk actually resides one found poke the address with 23 then list the line the line automatically causes the computer to change into the enlarged format by using different combinations of this technique you can make it a real pain for anyone to alter or analyse your basic code as an idea poking 28 will home the cursor and poking 31 will erase to the end of screen Nice one eh TRS8BIT vol 02 no 04 Christmas 2008 page 1 Trs8bit Dee and I wish all of our friends out there in trs 80 land a very Merry Christmas And a happy New year I hope once again I ve managed to put together some interesting items for this issue star billing in this issue must go to peter Phillips who has given us all a Christmas present by converting an apple 2 sudoku creation program to run on a level 2 16K machine of course it works just as well with disk basic According to peter the program was originally written in apple integer basic I must admit it seemed a bit odd to me However peter has done us proud yet another program for a 30 year old computer It works surprisingly quickly managing to produce a puzzle in approx 10 seconds Because of the programs size I ve placed a zip file for downloading it on the web site with a copy in both disk and cassette format just to save those rsi fingers I hope you enjoy it as much as dee and I have By way o
14. the large spaces in both programs are created by the down arrow and not the space bar for a longer game just increase the f loop I ve revamped an original article by Laurie Shields which gives some great ideas for changing lower case to upper case The small assembler program with notation is included together with a basic program that uses a usr routine to call it I hope you find it of some interest Anyone fancy changing it to convert upper to lower case Well That just about wraps up this issue I d love to have your feedback the next issue should be out early march 2009 so in the meantime Take care Bye for now dusty At the READY gt Prompt I was busy playing with my model1 the other day filling arrays with generated random numbers and I suddenly thought it would be a good idea if the machine gave me an indication that it was working ok other than TRS8BIT vol 02 no 04 Christmas 2008 page 3 Text Conversion And other bits From an original idea of Laurie shields None of my model 1 collections has the lower case mod fitted but matthew reed s emulator come with l c as standard all that s needed is a driver for the benefit of anyone out there without l c I think you ve only got half a computer Although I love my teletype font all program titles and prompts on the screen look infinitely better with l c as does any printer output l c is taken for granted on all m
15. time you should succeed part box of new 8 floppy disks So it you run a model 2 or any machines with 8 drives and you re having difficulties getting media again please let me know They are Memorex single sided double density soft sectored with 77 tracks Talking of model 2 s one sold on the uk s ebay for 75 there has been quite a few tandys sold over the last few weeks with model 1 s fetching between 18 and 35 and model 4 s fetching between 50 and 90 there s been considerably more sales of accessories books and software too for all models As at the time of writing there is a video genie for sale in an ebay shop The price is 80 It s nice to know there s still a bit of interest out there Continued on page 7 At the READY gt Prompt One really neat feature of disk basic is that it allows the use of hex and octal constants i e if you issue the command print amp h5bbb it returns the answer 23483 the decimal equivalent This Saves me having to get out my tandy o0o Here s a one liner from an original idea by Michael lyon TRS8BIT vol 02 no 03 september 2008 page 3 48k in the model 1 keyboard ec Kilpatrick now that general northern have gone out of business we thought it would be a good idea to see if it was possible to modify the model 1 keyboard to read 48k without having to add a decoder board with considerable help from my good fri
16. to z74 pin 5 this gate together with 2 other originally spare gates z73 pins 11 12 13 and z37 pins 8 9 10 will be used to decode the row and column addresses of the 64k ram chips pins 9 and 10 of z73 must have their incoming traces cut and replaced by links to a14 and a15 at z21 pin 15 and z73 pin 4 respectively z73 pin 8 outputs the a15 or a14 condition required in the first paragraph to address the top 48k of the memory map this signal is inverted by the spare nor gate of z37 8 9 10 and combined with ras in the spare or gate of z73 12 13 which in turn from pin 11 feeds the existing ram connection at z74 pin 10 note pins 8 and 9 of z37 must be separated and only one of them may be connected to pin 8 of z73 as although TRS8BIT vol 02 no 03 september 2008 page 4 pin 9 appears to be floating it is not possible to be 100 certain about pin 8 so it must be tied to pin 7 earth a14 and a15 must also be linked to pins 14 and 13 of the data selector z51 while it s output at pin 12 will be linked to the number 9 pins of each of the 64k rams here are the detailed changes necessary open up the keyboard and locate the following chips on the trace side of the board z21 z36 z37 z51 z73 and z74 i stuck a small number label on each chip to make sure i could always read them and locate pin 1 lay the keyboard component side down with the keys away from you cut the following traces
17. 28 9 a2 40 10 a14 23 10 a0 25 11 a8 22 11 d5 28 12 out 32 12 d2 32 13 wr 40 13 cas 3 14 intak 14 d1 22 15 rd 41 15 d0 30 16 mux 25 16 d3 26 17 a9 24 17 d7 20 18 d4 20 18 d6 24 19 in 33 19 vcc 20 d7 17 20 d4 18 21 int 31 21 a15 7 22 d1 14 22 a8 11 23 test 39 23 a14 10 24 d6 16 24 a9 17 25 a0 10 25 mux 16 26 d3 16 26 a10 4 27 a1 7 27 a13 6 28 d5 11 28 a11 9 29 gnd 1 2 49 50 29 a12 5 30 d0 15 30 phi 31 a4 6 31 pint 21 32 d2 12 32 out 12 33 wait 37 33 in 15 34 a3 6 34 phlda 35 a5 5 35 phan 36 a7 3 36 halt 37 gnd 1 2 49 50 37 pwait 38 a6 4 38 ilrq 39 gnd lev 2 only 39 phold 23 40 a2 9 40 wr 13 41 rd 15 42 ccdbs 43 mreq 1 44 d0dbs 45 mi 46 reset 47 rfsh 48 nni 2 49 gnd 8 37 29 50 gnd 8 37 29 The original article was in very poor condition and consequentially very difficult to read I hope I ve managed to copy all the details correctly Trs 80 video genie TRS8BIT vol 02 no 01 MARCH 2008 page 5 here s a nice little mod to the cassette version of electric pencil from an original article written by Rodney schreiner for several months i ve been using the cassette version of pencil to prepare manuscripts and letters using single sheets of 8 5 x 11 inch paper since pencil does not automatically pause at the end of a page i have to watch the printer and stop the program manually so i can insert a new she
18. CESS IT WITH CC0T BEFORE APPLYING THE C COMPILER AS YOU MAY HAVE GATHERED FROM ALL THIS THE LANGUAGE C WAS NEVER INTENDED TO BE IMPLEMENTED ON A SYSTEM HAVING UPPER CASE ONLY NEVERTHELESS HERE IS A WAY FOR IT TO BE DONE THIS PROGRAM IS RATHER SIMPLE AND THUS IT WILL NOT RECOGNIZE THAT SPECIAL CHARACTERS IN QUOTES ARE NOT SUPPOSED TO BE CONVERTED DEFINE LEFTCURLY 0X7B DEFINE RIGHTCURLY 0X7D DEFINE LEFTBRACK 0X5B DEFINE RIGHTBRACK 0X5D DEFINE CIRCUM 0X7E DEFINE UPARROW 0X5E DEFINE VERTIBAR 0X7C DEFINE BACKSLASH 0X5C DEFINE UNDERSCORE 0X5F CHAR IBUF 134 OBUF 134 MAIN ARGC ARGV INT ARGC CHAR ARGV BEGIN INT FD1 FD2 CHAR C IF ARGC 3 BEGIN PRINTF USAGE CONVERT OLD NEW lt CR gt N EXIT END TRS8BIT vol 02 no 01 MARCH 2008 page 8 o0o FD1 FOPEN ARGV 1 IBUF IF FD1 1 BEGIN PRINTF NO SOURCE FILE N EXIT END FD2 FCREAT ARGV 2 OBUF IF FD2 1 BEGIN PRINTF CAN T OPEN OUTPUT FILE N EXIT END WHILE C GETC IBUF 0X1A amp amp C 255 BEGIN SWITCH C BEGIN CASE LEFTCURLY PUTST BEGIN BREAK CASE RIGHTCURLY PUTST END BREAK CASE LEFTBRACK PUTSPEC L BREAK CASE RIGHTBRACK PUTSPEC R BREAK CASE CIRCUM PUTSPEC C BREAK CASE UPARROW PUTSPEC U BREAK CASE VERTIBAR PUTSPEC V BREAK CASE BACKSLASH PUTSPEC B BREAK CASE UNDERSCORE PUTSPEC U BREAK DEFAULT PUTC TOUPPER C OBUF
19. DATA 1 1 7 1 17 1 24 1 32 1 34 6 42 7 0 300 DATA 1 1 7 1 17 2 24 1 32 1 34 14 0 310 DATA 1 1 7 1 11 2 15 4 20 2 25 1 32 1 34 15 0 320 DATA 1 1 7 1 11 2 15 5 21 1 25 1 39 1 32 17 0 330 DATA 1 1 7 1 11 2 14 8 25 1 28 21 0 340 DATA 1 1 7 1 9 1 11 13 25 1 28 10 39 10 0 350 DATA 24 13 39 11 0 22 28 0 20 32 0 19 35 0 360 DATA 17 7 27 23 0 17 6 27 24 0 99 Here s this years xmas print The original can be viewed on page 3 I know you need to squint a bit at it but hey Give me a break It is Christmas after all TRS8BIT vol 02 no 04 Christmas 2008 page 7 o0o With thanks to peter Phillips here s your Christmas present from trs8bit It s a level ii 16K runable version of a sudoku creation program The more I run this program the more impressed I become with it On a standard level ii machine or within matthew reed s emulator running at 1 7 mhz it manages to produce a puzzle in approx 10 seconds Quite an impressive achievement for a 30 year old piece of hardware Ramp up the speed on the emulator and it s truly amazing Anyone out there fancy improving it How about an additional option to enter the numbers from an existing puzzle and calculate the answer instead of using all random numbers Don t forget to save you typing the program in a download is available on the website Just click on the named box Merry Christmas everyone and a happy new year TRS8BIT vol 02 no 04 Chris
20. END END IF C 255 C 0X1A DIGITAL RESEARCH WOW PUTC C OBUF FFLUSH OBUF END PUTST STRING CHAR STRING BEGIN WHILE STRING PUTC STRING OBUF END PUTSPEC C CHAR C BEGIN PUTC OBUF PUTC C OBUF END I hope you ve enjoyed this issue If you have why not drop me a line and tell everyone what you re up to with your Tandy If not Let me know and I ll try and improve the next issue which by the way should be out early June 08 And finally has anyone a pdf copy of pathways through the rom from ira s site If you have would you email me a copy It s the same address for all correspondence tia dustym beeb net TRS8BIT vol 02 no 02 june 2008 page 1 Trs8bit I can t believe that this is our 6th edition of trs8bit Time definitely goes faster as my age increases I hope you enjoy this edition as I feel there are some fascinating article to keep you amused Star billing in this issue must go to an article Roy T Beck has updated which was originally written for trstimes It s for any brave soul who would like to attach a hard drive to a model 1 3 or 4 If anyone has or has had a go I d love to hear how you got on This must be one of the most exciting and well researched article I ve ever come across for the trs 80 community There s A smashing one liner to calculate prime numbers Just as a matter of interest I can load up matthew re
21. O 3160 3130 Y 1 GOSUB 3400 3160 NEXT I 3170 FORI 1TO81 B I A I NEXT 3180 RETURN 3400 FOR J 0 TO 8 3420 W 9 J I Y V 9 J I Z 3425 P A W Q A V 3430 A W Q A V P 3470 NEXT J 3480 RETURN 4000 PRINT 4010 FORI 1TO9 A I I NEXT 4020 FOR I 1 TO 30 4030 X RND 9 Y RND 9 TRS8BIT vol 02 no 04 Christmas 2008 page 9 o0o 4030 X RND 9 Y RND 9 4035 IF X gt Y THEN 4030 4040 B A Y C A X 4050 A X B A Y C 4110 NEXT I 4120 RETURN 5000 PRINT 5005 FORI 1TO81 B I 0 NEXT 5010 FORI 1TO9 A I 9 A I NEXT 5015 P 1 5020 FOR I 0 TO 2 5030 FOR J 1 TO 7 STEP 3 5040 FOR K 0 TO 8 B P K A I J K NEXT 5045 P P 9 5050 NEXT J I 5060 RETURN 6000 REM 6010 INPUT ARE YOU SURE YOU WANT THE ANSWER Y N D 6020 IF D lt gt Y THEN RETURN 6030 F 1 FORI 1TO81 A I B I NEXT 6100 F CHR 191 L STRING 11 140 T CHR 188 6105 PRINT PRINT T L T L T L T 6110 FOR J 0 TO 8 6120 PRINT F 6130 FOR I 1 TO 9 K 9 J I 6140 IF A K lt gt 0 PRINT A K ELSE PRINT 6150 IF I 3 INT I 3 0 THEN PRINT F 6160 IF I 3 INT I 3 gt 0 THEN PRINT 6170 NEXT I 6175 PRINT 6177 IF J gt 7 THEN F CHR 143 6190 IF J 1 3 INT J 1 3 0 THEN PRINT F L F L F L F 6200 NEXT J 6210 PRINT 6220 INPUT HIT ENTER TO CONTINUE D 6230 RETURN 7000 REM 7010 FORI 1TO81 A I B I NEXT 7020 PRINT PRINT HOW DIFFICULT DO YOU WANT YOUR PUZZLE PRINT 1 EASY PRINT 2 MEDIUM PRINT 3 HARD 7030 INPUT A 7040 IF A l
22. ad been advertising 270 issues of byte for sale With a starting bid of 200 it was too much money for me but they would make very interesting reading Ebay com still manages to amaze me with the quantity and diversity of items still being offered for sale If only the postage costs from the states were not so high Just by way of advance notice my isp beeb net is closing down at the end of june08 this means a new home for trs 80 org uk has had to be found pretty sharpish I hope to accomplish the change over as seamlessly as possible but just in case I ll ask for you forbearance It also means of course my email address will change to dustym fabsitesuk com Please use this address with immediate effect I shall be sending an email to everyone who has contacted me over the last two years so hopefully no contribution to trs8bit will go amiss continued on page 10 At the READY gt Prompt Having bitten the bullet and started using matthew reed s emulator running newdos80 o0o Louis Pelletier has written a cracking one liner to calculate prime numbers it s surprisingly fast for just level 2 basic it calculates all the primes up to 1000 in under 10 seconds on a 16k level ii machine Don t believe me Just try it TRS8BIT vol 02 no 02 june 2008 page 3 Summary of radio shack hard drive parameters An updated article by Roy T Beck Which first appeared in trstimes Introduction
23. address with 191 Most of you are probably already familiar with this process so I won t say anything more about it except that disk users have TRS8BIT vol 02 no 02 june 2008 page 9 a real advantage in the use of DEBUG The interesting thing about super graphics is the method in which they work The S 80 converts all commands into one byte tokens to save memory it just happens that the command tokens are the same ASCII values as the graphics characters That s why a super graphics line contains only command words Now for the Heavy Stuff stay close We ve all been told that super graphics lines cannot be edited This is because the computer reads all the contents between quotes as regular character information rather than tokens If you re like me you find you need to edit the line that you ve slaved so hard over to convert to tokens There is a little trick that will permit you to edit your super graphics without losing your tokens If while you re editing the line you C hange the first quote in the line to an asterisk the line will be retokenized Then when done editing POKE the asterisk back to a quote and Voila The line is converted back to super graphics after editing This little trick should prove useful whenever you find you need more characters in a line which is already packed For those of you with a disk system I suggest doing all the aforementioned with DEBUG the monito
24. e string field For example the expression defines a string field of 4 positions the beginning and end percent signs count as one space each when you use this print mode the computer takes the operand string supplied by you and tries to put it into the print using field for example 10 print using dusty will print dust all characters that don t fit into the print using statement are truncated any percent sign that is not beginning or ending a string field is regarded as just another character You can of course pre define your print using string to save memory and effort for example 10 a 20 b 27 letsbie avenue 20 print using a b Will print 27 letsbie this is a neat little device for limiting the width used by fields within print outs or screen displays And while I m mentioning the lack of lower case I ve also included one of the most useful lower case drivers I ve ever used it works great with Matthew reed s model 1 emulator which by the way has had another update See trs 80 org for details All of the one liners and programs for trs8bit are either written devised or tested using the emulator I m quite hooked on the windows virtual cassette That s about it for now keep in touch dusty o0o At the READY gt Prompt within level ii basic there isn t an xor instruction only and or not however it is possible acco
25. e a go at the one liners in this issue They are all about hand and eye coordination The idea being that you just type in the respective screen number when bits of it light up The first one was quite simple but the other one took a bit more TRS8BIT vol 02 no 04 Christmas 2008 page 2 printing endless random numbers a simple flashing asterisk as used for the cassette tape i o would be just the ticket it can be done quite easily in basic as 10 if peek 15423 42 then poke 15423 32 else poke 15423 42 the top right hand corner of the screen is memory address 15423 if it contains and asterisk ascii 42 then write a space ascii 32 else write an asterisk this works fine but is not very elegant when compared to the code in rom which simply xor s the contents of 15423 with 10 writing a small machine code routine should be quite simple but then I thought as the routine is already in rom at 022ch according to James lee farvour s m s basic decoded I could use that for level 2 users just poke16524 44 poke16527 2 for disk basic users type defusr0 amp h022c x usr 0 this little bit of code will do the equivalent of a gosub and put or wipe out an asterisk in the top r h corner of the screen as per the example below effort to get it down to just the one line It was those pesky if statements They will keep dropping you through to the next line when their conditions are met Don t forget
26. ed s emulator run the program print out the answers and close down in less time that dee s laptop computer under windows xp takes to power on There s the usual at the ready prompt and various other little snippets I ve been playing around with over the last few weeks At long last I felt I had to buck up courage and have a go at running Mathew reed s emulator with disks a giant leap for mankind you might think The only dos I own is newdos80 v2 and I m on a steep re learning curve see at the ready prompt for what I mean During the 80 s I never managed to afford an e i and disk drives of my own but I was lucky enough to be able to use ones owned by friends I has half a dozen disks of my own and a genuine copy of newdos80 As you can imagine I m really enjoying myself As an aside I ve just been elected treasurer of the local branch of the british printing society and have decided to do all the accountancy work on my M1 emulator by using electric pencil and visicalc I ll let you know how I get on Thanks to everyone who offered me copies of pathways through the rom It was greatly appreciated Thanks must go to david cooper for being the first to offer and letting me have many other bits and pieces some of which I haven t seen for years Knutt has released his latest program playcass It s available as a download from his website There is a link to his
27. end guy grantham who had already modified his video genie we have succeeded here is how we did it the memory signals combined with ras and cas to read up to 16k ram require a15 low and a14 high from 16k to 32k require a15 high and a14 low from 32k to 48k require a15 high and a14 high therefore to read all 48k either a14 or a15 or both must be high at the relevant time originally the computer could only recognise up to 16k of ram because it was only decoded to read memory while a15 was low due to z73 pins 4 5 6 or gate controlling z21 2 line to 4 line decoder at pins 14 and 2 these signals will be retained for video keyboard and rom but no longer used to generate the mem and ram signals by opening links 2 3 4 5 on x3 new connections are required to generate the mem signal which comes from pin 6 z74 this signal now has to be active low whenever there is a rd active excluding calls to reserved memory 3000h to 37ffh which is required for disk and printer i o or to the keyboard at 3800h to 3bffh or again to the separate video ram at 3c00h to 3fffh all these invalidating conditions are met when a15 and a14 are low and a13 and a12 are high as provided by the output from z21 pin 12 to input pin 4 of z36 so by cutting the trace to pin 5 of z74 and linking pin 4 of z36 to this pin the required conditions of mem are met for 48k ram z73 pins 8 9 10 are now spare by virtue of cutting the trace
28. er but so far I haven t been able to get it running using the tandy printer to keyboard interface connector as yet It seems to power up ok but then just sits there looking amazing but doing nothing I m still looking for more information regarding the aculab floppy tape please let me know if you come across anything of interest It would be most appreciated Well I think that just about wraps up this issue If you ve any special requests or ideas for the xmas issue please ask and I ll do my best to include them In the mean time Take care dusty Hide your code By Philip Case here s a tip about using control code functions to make your programs harder for other people to list examine and or amend if you remembers chr 23 puts your model 1 s screen into the enlarged mode 32 characters per line consequently anything that s on the screen in the 62 character mode will lose every other letter when you switch into the enlarged mode you can illustrate this by typing anything on the screen pressing shift right arrow then printing chr 23 home cursor by doing this you are entering a control character in the immediate mode You can put these codes in your basic program coding by adding a rem ark at the end of an important line then and asterisk here s an example 10 for a 1to10 nexta rem this line will still function in the regular way after editing the line go back and find
29. erSoft Supreme HD Drivers series RS both will work with all of them The MISOSYS drivers are easier to install but the Powerboat Supreme Drivers allow greater flexibility when you want maximum control over placement of partitions note The driver RSHARD that Roy refers to is currently available for downloading at www tim mann org A big thanks go to Tim Mann amp Roy Soltoff for this facility It is still possible to buy MFM drives I ve seen them advertised on Ebay on a number of occasions Ed Packing and super graphics by Phillip Case By now most of you have seen those funny listings which appears to be garbage Programs like android Nim Bee wary and Star Scout all look like bad loads when listed This is due the use of a process known as packing the graphics The reason these programs have their graphics strings packed this way is to save memory By packing your strings in this memory you reduce the amount of overheads memory needed by about two thirds To create super graphics one simply changes the value of the characters between the quotes in a line to read as graphics codes For example 10 A To change this line one would simply POKE the memory location that contains the with the value of the graphics character needed in this case let s use a full graphics block or CHR 191 To change line 10 to print a CHR 191 we find the address which contains the and POKE the
30. et of paper the tediousness of this task finally got to me and i decided to investigate the program to see if i could modify it so that it would stop at the end of each page after a lengthy search through the code i located the spot at which the program tests for the final line of a page at this point the program jumps to the page spacing routine by changing only 2 bytes i altered this jump to a return to the main system now when the printer reaches the end of page it stops and i can load a fresh sheet of paper at my leisure all that is necessary to continue printing is to move the cursor to the start of the next page i require printing and off i go the changes i ve made are detailed below change 4f3fh from 28 to c8 4f40h from 06 to 00 only bytes 4f3f and 4f40 are changed this can be accomplished by using t bug relocated to high memory after the 2 changes are completed a new system tape can be written from t bug the starting address is 4350h the ending address is 5374h and the entry point is 4350h this new version of pencil cannot print continuously since the alterations above force it to stop at the end of each page However if i need continuous printing i can use my original pencil cassette o0o File transfers on the models 1 and 100 by Leon heller if you are using the Tandy rs 232 board it is not advisable to just plug the cable from the model 1 into the back of the model 100
31. f a xmas tradition if we ve been about long enough to have a tradition I ve produced another ascii print with a suitable xmas flavour The program is nearly identical to the one used last xmas except for an additional line for you lucky people with more than 16k of ram Other than that it s only the data lines that have changed Perhaps some of you will remember that a couple of issues ago I mentioned that I was taking over the job as treasure of my local branch of the British printing society There are a very small number of transactions throughout the year so I thought it would be nice to try and run the accounts using visicalc and electric pencil It actually worked out quite well I d forgotten just how good visicalc is was The only problem I encountered was with the resulting print out I wanted to use this type face teleprinter and not having a teletype 33 anymore I had to cheat a little I downloaded a copy of my end of year statement to windows using matthew reed s trsread program and used windows notepad to change to the required font Just to refresh your memory I ve included a model 3 visicalc crib sheet just in case you want to play too Sorry if the reproduction is not too good but the original is on the waxy paper we all knew and loved so much Dee s been playing with a new game on her Nintendo ds which has yet again inspired me to hav
32. ime and the sharp hard little knob would play havoc with your finger s with the crank however it takes no more than 2 or 3 minutes to wind the entire ribbon o0o Continued From page 2 I ve managed to do a deal with fabsitesuk com who allow web hosting for very moderate fees if you re a non profit making organization Talking of news letter contribution they are a bit thin on the ground If you re having fun with your trs 80 I d love to know what you re up to Just an update of a few lines would be appreciated My email address on the web site has been changed from the date of this issue so in case you loose this note of it just click on the email button Well that about wraps up this edition I hope you found something of interest so until September Bye for now Dusty TRS8BIT vol 02 no 03 september 2008 page 1 Trs8bit Welcome to the September edition of trs8bit Just a quick thank you for the feedback kind comments in general and in particular about roy s hard disk article in the last issue It seems at least two people have been assisted by it How about letting us all know how you re getting on Contributions have been a bit thin on the ground most probably due to the august holiday time but I hope that I ve managed to find odd little bits of interest for you The usual one liner makes an appearance and a number of snippets in at the ready
33. in ldos If anyone would care to send it in I ll be happy to publish it in the next edition of trs8bit not wishing to teach my grandmother to suck eggs but line 40 is also a nice little wheeze if you haven t come across it before the result in basic of the statement m gt 127 will evaluate to 1 if true or 0 if not true even without an TRS8BIT vol 02 no 04 Christmas 2008 page 5 o0o if command before it the expression 256 m gt 127 will result in either 256 or 0 for either true of false therefore m 256 m gt 127 will in one statement result in the value m 256 if m is greater than 127 and just m otherwise so by reading from the data statement pairs of values into variables l and m you guessed it least and most significant we calculate the combined value as 256 m 256 m gt 127 l without an if or else in sight N B it is necessary to re define the usr routine each time before use since introducing other simple variables into the running of whatever application you put this routine to could cause the actual bytes of memory allocated by basic for this array to be changed 1 ORG 8B00H load 8800h 2 8B00 CD7F0A START CALL 0A7FH get string pointer 3 8B03 7E LD A HL get length of string 4 8B04 B7 OR A test if null 5 8B05 C8 RET Z if zero bytes return 6 8B06 47 LD B A put byte count into reg b 7 8B07 23 INC HL point to lsb if string addr 8 8B08 5E LD E HL
34. ires as they are now attached to the HDC instead of the bubble notes for table 2 1 Solder wire to feed through near pin 6 Cut trace to pin 5 of J1 to prevent feeding 5V into the 20 c cable 2 Cut trace to pin 5 of J6 to prevent feeding 5V into the 20 c cable 3 Use empty pin hole of J6 instead of J5 4 The pad is marked R97 but no resistor is actually installed there All of the drives I deliver to customers are connected in the generic fashion described above This simplifies matters for both me and the customer and of course the logic works the same as always as the generic connection connects the three wires at the destination the HDC instead of at the source the bubble Over the last couple of years I have connected many different drives into our Radio Shack boxes up to and including the 70 Meg drive and all work well Be aware that the 12 Meg 35 Meg and 70 Meg drives all suffer from a bit of puffery They were advertised and sold by Radio Shack with those labels but the labels are only strictly true when installed on machines of the Model 11 family because those machines formatted more bytes per track than LS DOS and LDOS can do The real limits on those drives when used in a model 1 111 or 4 system are 11 304 960 bytes 33 554 432 bytes and 67 108 864 bytes respectively based upon 8 heads and 230 512 or 1024 cylinders Following the usual advertising practice you could more properly call
35. le this area The cylinder at which write current should be reduced is specifically stated by the drive manufacturers but our formatters simply assume a value and go ahead without asking us If you review the drive specs the recommended value is typically about half the total number of cylinders and I believe this is what the formatter programs assume Furthermore the newer drives take care of this function in hardware and so regardless of what the software and controller say the later drives do their own thing Don t worry about it it is not critical The cylinder to begin write pre compensation varies considerably Most older drives set it at about 1 2 of the total cylinders but some of the later ones don t want any pre compensation Again this value appears not to be critical and is taken care of in the driver software I have received one only report from a user who said he had to patch his code to suppress pre compensation in order to make his drive work but I lack any further details It seems to be a factor of concern generally Finally the average access time is a bragging point among IBM users but for us TRS types hard drives access so much quicker than floppies that the whole process seems like magic anyway For the drives we are using the access times are as shown in Table 1 and except for the 70 Meg drive are SLOW by IBM standards Even so the change from floppies is dramatic and y
36. load in e register 9 8B09 23 INC HL point to msb of string addr 10 8B0A 56 LD D HL de now has addr of string 11 8B0B 1A LOOP LD A DE get byte from string 12 8B0C FE61 CP a if lt lowercase a 13 8B0E 3807 JR C NEXT ignore it 14 8B10 FE7B CP z 1 if gt lowercase z 15 8B12 3003 JR NC NEXT ignore it 16 8B14 E65F AND 01011111B mask out bit 5 17 8B16 12 LD DE A put back into string 18 8B17 13 NEXT INC DE point to next character 19 8B18 10F1 DJNZ LOOP go round loop 20 8B1A C9 RET all done return to basic 21 END TRS8BIT vol 02 no 04 Christmas 2008 page 6 Next issue out early march 2009 All contributions welcomed 10 cLEAR500 20 M MERRYXMASMERRYXMASMERRYXMASMERRYXMASMERRYXMASMERRYXMASMERRYXM 30 GOSUB 200 40 READ S 50 IF S 0 GOSUB 150 60 READ L 70 T MID M S L 80 X PEEK VARPTR P 1 PEEK VARPTR P 2 256 90 REM THE LINE BELOW IS FOR 16K MACHINES 100 IF X gt 32767 X X 65536 110 FOR Y 1TOL 120 POKE X S Y ASC MID T Y 1 130 NEXT Y 140 GOTO 40 150 LPRINT P 160 GOSUB200 170 READ S 180 IF S 99 THEN END 190 RETURN 200 P STRING 63 32 210 RETURN 220 DATA16 1 0 16 1 0 15 2 18 1 0 15 2 18 2 0 13 1 15 2 18 1 0 230 DATA 13 6 0 12 8 0 5 24 0 5 1 13 2 18 3 28 1 0 240 DATA 5 1 12 3 18 4 28 1 0 4 1 12 3 18 3 29 1 43 5 0 250 DATA 3 1 12 4 18 2 30 1 43 6 0 2 1 11 10 31 1 42 8 0 260 DATA 1 1 11 12 32 1 42 9 0 270 DATA 1 1 9 1 19 3 23 1 32 1 36 4 43 7 0 280 DATA 1 1 8 2 20 1 23 1 32 1 35 6 43 5 0 290
37. mainder when a division operation is performed An elementary school student learning division would learn that 5 divided by 3 is one remainder 2 Thus 5 MOD 3 equals 2 In a similar fashion one could derive that 103 MOD 25 equals 3 The MOD function on the Model 2 takes the form A MOD B Its equivalent on the Model I or Model 3 would be A InT A B B Thus the equivalent of 103 MOD 25 as in our previous example would be 103 iNT 103 25 25 which as stated above simplifies to 3 MOD does not save a significant portion of execution time It does make code using this function a bit easier to read but this I believe is far outweighed by the incompatibility it causes Since it is extremely easy to construct a MOD function which will work on virtually any version of BASIC I would strongly advise against using this function Don t forget the Christmas issue TRS8BIT vol 02 no 03 september 2008 page 6 TRS8BIT at a glance trs 80 printer comparison chart cira early 1980 s Centronics 737 Epson MX 80 Oki Microline 80 CGP 115 Quickprinter 2 DMP 100 Cannon BJ 10sx LP II Weight lbs 12 12 14 1 8 8 6 3 7 Size 5 x 14 5 x 11 4 2 x 14 7 x 12 4 25 x 13 5 x 9 75 8 5 x 8 5 x 3 3 5 x 7 x 9 5 16 x 8 25 x 5 3 31 x 22 x 4 85 interface parallel serial P P P Both Both Both P speed 50 cps 10 cpi 80 cps 10 cpi 80 cps 10 cpi 12 cps 64 cps 50 cps 10 cpi 110 cps
38. nd if you are connecting a computer to another via their rs 232 serial ports you need a device call a null modem this is just a cable with appropriate connectors wired in such a way that each computer appears as a modem to the other with a couple of db 25 connectors and a few pieces of wire two screws and a few nuts you can easily build a null modem for a few pounds in about 20 minutes all you do is place the connectors back to back and link the pins between the connectors according to the table below then you fix the two connectors together using the screws and nuts as shown below if you want to be really posh you could use studding spacers and a small box of course I used a male and female connector as this enables me to connect my model 1 or model ii to most other systems by wiring the pins on a one to one basis with connectors of the appropriate gender you can easily make what is termed as a gender changer o0o TRS8BIT vol 02 no 01 MARCH 2008 page 4 not rd and wr hence the as opposed to the bar cas can be obtained from the cpu board inside the genie on pin 6 of z39 mux can be obtained on pin 5 of z37 also if you wish out is available on pin 8 of z15 whilst in is available on pin 6 of z15 1 ras 43 1 gnd 8 37 29 2 sysres 48 2 gnd 8 37 29 3 cas 13 3 a7 36 4 a10 26 4 a6 38 5 a12 29 5 a5 35 6 a13 27 6 a4 31 7 a15 21 7 a1 27 8 gnd 1 2 49 50 8 a3 34 9 a11
39. odern computers I doubt whether anyone ever thinks about it these days however once l c is fitted or being used problems can arise when string comparisons are required for example a stock number of 123xyz is not the same in uppercase as it is in lower case this is most annoying as a routine in basic to check input and convert any lower case to uppercase can be rather slow and will invariably invoke a string garbage collection freeze up well that was the problem I came across and as a result the following usr routine emerged in machine code it is easy once we know where abouts in memory the character string is located and also how many bytes are involved microsoft must have had just this sort of problem in mind when they put together lii basic as the function varptr tells us all that we need to know by simply including it within the usr brackets to get the value enclosed in the usr brackets in our case the varptr of the possibly lower case string we have to call a rom routine at 0a7fh and the information returns in the hl registers the information is in fact the address of the first byte of three that give details about the string variable and this one is simply the length of the string if it s zero then we have a null string the largest would be 255 which is why the longest string we are allowed is 255 bytes as any more would require more than one byte for the size the next two bytes
40. ogic in the HDC The quirk is that if the lamp burns out or fails to make good contact in its socket then the 5 volts does not get to the logic and the HDC sees 0 volts which it interprets as a write protected condition The result is the DOS cannot write on a drive even though the write protect was not deliberately engaged With a burned out lamp the drive is continuously write protected The lamp by the way is rated 5 volts 55 milliamp The current draw is not critical anything from one milliamp to 100 milliamp will work The problem is availability of this special lamp An emergency solution is to replace the burned out lamp with the one from the green ACTIVE socket The lamps are the same and the system doesn t care if the green lamp works or not I have chased out the original wiring of all the Radio Shack drives either personally or through other helpful persons I especially want to thank Art McAninch of Borger TX and Fred Oberding of Sausalito CA for their kind efforts and communications TRS8BIT vol 02 no 02 june 2008 page 6 Table 2 shows the original hook up plus an alternate and simpler generic arrangement for master drives especially where some other bubble is being installed See the sections headed generic for the simpler connections The advantage of the generic connection is that you can thereafter remove or exchange drives without having to unsolder the three w
41. orth a visit if you re interested There s a clear and comprehensive walk through instruction set for downloading models 1 and 100 using st 80 iii and details of how to build a null modem Both of these articles were originally written by Leon Heller and published in natgug news Talking of Leon he was the first person I came across who sparked my interest in the language c If I remember correctly there was a version of small c available for the model 1 but it was only produced for disk systems On early pc s I became involved with the American mix c language It had a big user base in the states with massive amounts of freeware functions but As the years progressed I found the curly curved and straight brackets more and more difficult to see no pun intended so I moved back to cobol pick and as a consequence basic I still think that c is a neat powerful and compact language however at times it can be a bit on the obtuse side On the subject of c I ve found on one of the many shareware cd s I have a nice little c source program for use on computers with only upper case TRS8BIT vol 02 no 01 MARCH 2008 page 2 output code which is the percent sign the percent sign marks the beginning and the end of a print location to be filled with string data between the 2 percent signs is a given number of spaces These spaces define the width of th
42. ou will enjoy Radio Shack hard drives anyway Most drives have buffered seek which allows the controller to send stepping instructions at the 10 microsecond rate The drive actually just holds the count in an internal register until the controller stops sending The drive then moves its heads at its own best rate and stops on the desired cylinder A few very old mostly 5 Meg drives lacked this feature and with these you must tell the controller to send the stepping pulses at 3 millisecond or greater intervals Always try the 10 microsecond step rate first and if the formatter chokes reports most TRS8BIT vol 02 no 02 june 2008 page 8 o0o cylinders bad then try slower stepping rates until you find one that works Here is a warning to NEWDOS 80 v2 5 users The hard drive version of NEWDOS 80 is V2 5 and it works fine on the old large HDC boards However there is a bug in NEWDOS formatter which prevents operation on the new smaller HDC s Fortunately this bug was squashed by an Aussie and a friend of his sent the cure along to me The patch to HDFMTAPP the NEWDOS formatter is as follows Using SuperZap DFS of file HDFMTAPP CMD FRS1 MOD D1 Find AF 32 CB 00 Change to 3E 0F D3 CB All of the drives in Table 1 are physically and electrically interchangeable There are actually many more floating around they just have to be MFM types The MISOSYS RSHARD5 6 drivers and Pow
43. pin 1 of z13 fit a thick wire from the 5v pin above pin 7 of z1 to the pin above pin 8 of z17 fold the keys over on top of the board and turn the whole assembly over very carefully bend up pin 9 of each of the 64k ram chips not too far or they may break and insert them in to the empty ram sockets the same way round as the 16k chips making sure that each pin 9 is clear of the top of the socket as that might be at 5v contacts may be TRS8BIT vol 02 no 03 september 2008 page 5 o0o o0o slightly proud on some types of sockets wire all the number 9 pins together and connect a wire from pin 12 of z51 to the nearest pin 9 of the rams carefully recheck that the 12v trace is definitely cut and the system is ready to go it is not essential to cut the 5v rail but it should be done as a safety measure cutting the original 5v rail is a very complicated job and is best left alone hence the comment about pins 9 being well clear of the socket as that is still at 5v note do not use texas 64k rams as they have a different refresh system and cannot be used without further modifications to the computer circuitry I don t like mods Anon MOD is an arithmetic function found on the Model II As with SWAP this function is useful but it can very easily be duplicated on a computer without this function such as the Model I or Model Iii MOD signifies the integer re
44. r which is a part of DOS More mileage from epson ribbons it is possible to extend the life of Epson mx 70 and mx 80 ribbon cartridges by flipping the ribbon over in the cartridge since the print head strikes off centre on the ribbon flipping the ribbon exposes a fresh surface here s a simple technique for doing just that take an ordinary paper clip and bend it as shown in figure 1 lay this aside within easy reach now take the ribbon cartridge and refer to figure 2 lift the ribbon at the end near the ribbon advance knob and give the ribbon half a twist turn the advance knob a few turns to feed the twisted ribbon into the cartridge through the advance mechanism at this point the ribbon cartridge should look as it did before except for a half twist in the exposed portion take the paper clip crank you made earlier and insert the loop end into the ribbon advance socket on the cartridge this is on the bottom of the cartridge opposite the advance knob as in figure 3 now use the crank to advance the ribbon until the half twist inside the cartridge comes out the other end that s all there is to it the ribbon is now flipped over it s the paper clip crank that makes this idea practical without this you would have to advance the ribbon with the knob since there are 20 yards of ribbon o0o TRS8BIT vol 02 no 02 june 2008 page 10 in the cartridge this could take quite some t
45. rding to john Phelan to use the following a xor b a or b a and b and obtain the correct result in the last edition I mentioned the print using sign so it seems only fair to feature the other string o0o Here s a great one liner for displaying characters rapidly to the screen by Patrick boyle TRS8BIT vol 02 no 01 MARCH 2008 page 3 trs 80 model 1 genie edge connector cross reference From an original article by Ken Robinson The following table shows the pin inter connections to obtain the trs 80 bus from the video genie in the table the symbols used either side of the genie pin number have the following meaning nn indicates an addition to the genie bus nn indicates a similarity between the genie and the trs 80 but not an identity an aculab floppy tape and an lnw expansion board controlling disks can be run off an expansion bus using the following substitutions pin 12 out can be obtained by or ing genie pins 40 and 38 pin 13 vr can be obtained by or ing genie pins 40 and 43 pin 14 intak can be obtained by or ing genie pins 38 and 45 pin 15 rd can be obtained by or ing genie pins 41 and 43 pin 19 in can be obtained by or ing genie pins 38 and 41 suitable or gates can be found on the 74ls32 which is a quad array unless intak is definitely required ir can be left cut for most applications it is worth noting that rd and wr on the trs 80 are in fact nenrd and memwr a
46. s HDC is 8 and 1024 respectively All of these drives are full height unless noted to the contrary Incidentally the bare hard drive is also commonly referred to as the bubble and occasionally I use that term to distinguish the hard drive from the overall package which includes the HDC and the power supply all in a case The bubble is called that because the heads and platters are located inside a sealed dust tight chamber in the drive Don t ever open the sealed chamber that should only be done in a Clean Room TRS8BIT vol 02 no 02 june 2008 page 4 Notes for Table 1 1 This drive was used in most Radio Shack 5 Meg boxes Cat No 26 1130 Some of these drives require the step rate to be set at 6 or even more This corresponds to 3 milliseconds Try the default value of 10 microseconds If the step rate is too fast verification will report numerous bad tracks lf this occurs repeat the partitioning with 6 which should work 2 Apparently some Radio Shack 5 Meg boxes had this drive 3 This drive was not used by Radio Shack but is mentioned in some of their Service manuals 4 This drive was used in all the Radio Shack 15 Meg boxes Cat No 26 4155 5 This drive was used in all the Radio Shack 12 Meg boxes Cat No 26 4152 6 This drive is widely available and works well in Radio Shack boxes It is a half height drive but is a drop in fit in place of a full height drive 7 This drive
47. site on trs 80 org uk Have a look it s yet again another remarkable piece of software just released for a 30 year old piece of hardware There has been a reduction in the amount of traffic on the uk s ebay for trs 80 related items for quite a while Various books seem to fetch a few pounds each TRS8BIT vol 02 no 02 june 2008 page 2 v2 here s a timely reminder of something else I d completely forgotten In order for the cassette programs to load and save a cmd t must be issued immediately before any basic tape input output operation These operations are timing sensitive and are affected by interrupt driven tasks such as trace amp clock Just to remind you the commands affected are Cload cload csave input 1 input 2 system print 1 and print 2 Don t forget to enable interrupts when you have finished with the cmd r command and yes before you ask I did And finally just a little bit of history turned up the other day Tucked away inside a book was a little cloth badge that someone had made for natug members when the group first started before the name was changed to natgug It s strange I can quite clearly remember Brian issuing them but I can t remember who it was who had them made Is there s anyone out there with a better memory than me who can remember who it was and a couple of model 4p s ranging from 12 40 each someone h
48. t 1 OR A gt 3 THEN 7020 7050 W 2 A 20 RND 2 1 7060 FOR I 1 TO W 7070 X RND 81 7080 IF A X 0 THEN 7070 7090 A X 0 7100 X 82 X 7110 A X 0 7120 NEXT I 7130 RETURN 8000 REM Porting comments 8010 REM 4000 Creates a random ordering of 1 9 8020 REM 5000 Fills puzzle with rotations of the random ordering 8030 REM 3000 More or less permutes the columns 8040 REM 7000 Hides some of the elements 8050 REM 6100 prints the puzzle array TRS8BIT vol 02 no 04 Christmas 2008 page 10 TRS8BIT vol 02 no 04 Christmas 2008 page 11 TRS8BIT vol 02 no 04 Christmas 2008 page 12
49. t the values into the array we multiply the second one of the pair by 256 and add it to the first but checking that the result is not greater than 32767 before allocating it to the integer array if the result is greater than 32767 then subtract 65536 first however I don t like these big numbers and as the only way to end up greater than 32767 is for the second number of the pair to be greater than 127 in the first place then this is simpler to sort out if you are fortunate enough to be using the zen editor assembler then include a load 8800h command just after the org statement and then peek at memory addresses 8800h to 881ah and get the decimal values of the machine code bytes convert these into data statements and your finish program should look something like the one on page 5 it is possible to go even further to make life much easier it s an interesting and clever little trick if you re using zen or any editor assembler that allows you to load code into memory and newdos80 V2 you can create the data lines for your program automatically viz open 0 1 data bas 1 110 data forx amp h8800 to amp h881a 1 peek x next 1 chr 13 close and then load into basic data bas list the program and you ll see you re already half way to writing your program and not had to go through the hassle of converting a load of hex values to decimal I assume that a similar statement is allowed
50. tmas 2008 page 8 5 DEFINTA Z 10 DIM A 81 B 81 20 PRINT LARRY NELSON S SUDOKU FOR THE APPLE II 25 PRINT CONVERTED FOR TRS CONVERTED FOR TRS CONVERTED FOR TRS CONVERTED FOR TRS 80 BY PETER PHILLIPS 80 BY PETER PHILLIPS 80 BY PETER PHILLIPS 80 BY PETER PHILLIPS 30 PRINT INPUT WANT INSTRUCTIONS D IF LEFT D 1 Y THEN GOSUB 1000 40 PRINT CREATING 50 GOSUB 4000 60 GOSUB 5000 70 GOSUB 3000 80 GOSUB 7000 90 GOSUB 6100 95 F 0 100 PRINT 1 NEW PUZZLE PRINT 2 ANSWER TO PUZZLE 105 IF F 0 THEN PRINT 3 SHOW PUZZLE AGAIN 107 PRINT 4 QUIT 110 INPUT A 120 IF A 1 THEN 40 130 IF A 2 THEN GOSUB 6000 135 IF A 3 AND F 0 THEN GOSUB 6100 140 IF A 4 THEN END 150 GOTO 100 1000 PRINT SUDOKU IS A NUMBER PUZZLE IN A 9X9 GRID 1010 PRINT THE GRID IS SPLIT INTO 9 3X3 MINI GRIDS 1020 PRINT SINGLE DIGITS FILL THE GRID THE DIGITS 1040 PRINT MAY BE IN ANY ORDER THERE ARE JUST 1050 PRINT THREE RULES FOR SOLVING THE GRID 1060 PRINT EACH ROW MUST HAVE ALL THE DIGITS 1 9 1070 PRINT EACH COLUMN HAS ALL THE DIGITS 1 9 1080 PRINT EACH MINI GRID MUST ALSO HAVE ALL THE 1090 PRINT DIGITS FROM 1 9 1100 PRINT INPUT HIT ENTER TO CONTINUE D 1110 RETURN 3000 PRINT 3010 FORI 1TO81 A I B I NEXT 3020 FOR I 1 TO 7 STEP 3 3030 X RND 6 1 3040 IF X 0 THEN 3160 3050 Y 0 Z 2 3060 IF X 1 THEN Y 1 3070 IF X 3 THEN Z 1 3080 GOSUB 3400 3090 IF X lt 4 THEN 3160 3100 IF X 5 THEN 3130 3110 Z 1 GOSUB 3400 3120 GOT
51. was not used by Radio Shack but is listed here because it is one of the generic MFM drives frequently mentioned 8 This drive was not used by Radio Shack but is listed here because it is the other generic MFM drive frequently mentioned 9 This drive was used in the Radio Shack 35 Meg boxes Cat No 26 4171 It has auto parking built in it parks itself at the highest cylinder on loss of power 10 This drive was used in the Radio Shack 70 Meg boxes Cat No 26 4173 The infamous three wires The three wires l am referring to are three wires which run from a harness in the hard drive case to specific points on the bubble varying with the actual bubble used in the system Radio Shack soldered these three wires directly to the PC board of the bubble which could easily be done on the production line It does pose a problem to us users especially when we wish to swap bubbles It may be useful to explain the purpose of the three wires The wire colours are as found in a master drive the colours are different in a slave drive The yellow wire responds to the drive select signal The system can electrically accommodate up to 4 drives one master and three slaves There is a drive select line for each of them The selected drive has 0 volts on its select line and the other three stand at 5 volts When the master drive is selected the yellow wire will be at 0 volts and the green light may be on The reason
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