TRS-80 <-> Timex Sinclair interface

[syzygy]

I was reading another thread and it reminded me about this project I did, "back in the day". I only had a Timex-Sinclair for a short time and honestly do not remember much about them anymore. Mine was, I think, a $99 model and it blinked the screen and had a pretty tough to use membrane keyboard. I built this 8255-based interface between the two to make it easier to play with.






Flow charts:



I am wondering if I didn't do it for some specific reason (e.g., built one for someone, because I wrote up a little manual, which I rarely ever did - usually a few notes just to remember what/why I was doing something.

I dug up a couple of BASIC programs that I might have used at the time:

5 D=0
10 CLS:OUT63,192
20 IF(INP(62)AND32)=32THENA=INP(60)ELSE20
30 PRINTA;:IFA=255THENS=S+1
35 IFD<>ATHENPRINT"ERROR AFTER ";S;" PASSES":END
38 D=D+1:IFD=256THEND=0
40 GOTO20

10 'TRS-80 TO SINCLAIR SEND DATA PROGRAM
20 'SENDS A TEST SEQUENCE (0-255) REPEATEDLY
30 '
40 CLS
50 OUT63,192:'SETS 8255-A TO MODE 2
55 A=0:N=-256
60 A=0:N=N+256:PRINT@100,N;" BYTES SENT SO FAR"
70 IF(INP(62)AND128)<>128THEN70
80 OUT60,A:PRINT@320,"SENDING OUT DATA BYTE VALUE= ";A
90 A=A+1:IFA=256THEN60ELSE70
100 'EXIT WITH THE BREAK KEY

But I found some asm code that looks like it may have had bad sectors or is otherwise incomplete.

 

[syzygy]

...and BTW, least anybody is thinking I was some EE designer, I was definitely not. Strict hobbyist at the time and just liked doing challenging "new" projects. In this time period, one would read stuff and then think "hmmm, I wonder if I could do that with this".

Also in the folder were these two articles (first page). The 8255 interface to a TRS-80 was almost definitely what I used and I can see where I used "white out" to mask a portion of the interface - I think it covered a manual reset that I didn't think was necessary (or I didn't have a switch).

The other article was about getting a Timex and an H8 to talk and I don't know why I would have saved it in the same place unless it gave me the idea to try it with the M1.

At the time, it was an amazing and exciting hobby.

 

[SiriusHardware]

Brilliant, thanks for posting - I have to admit I wasn't expecting it to be a parallel computer to computer interface, so that was a bit of a surprise. Thanks for keeping all of this together for all of that time.