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TRS 80 Model III Hi-res Graphics Board


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  TRS 80 Model III Hi-res Graphics Board by Bill Degnan - 09/05/2014 10:43
TRS 80 Model III 26-1125 hi-res board demo image
TRS 80 Model III 26-1125 hi-res board demo image. Click on image for larger view.

Here are the initialization commands necessary for a model III with programs written with micro-labs GBASIC, and a model III 26-1125 graphics board:

A=PEEK(16912) OR 16
POKE 16912, A
OUT 236,A

TRS 80 Model III 26-1125 hi-res board
TRS 80 Model III 26-1125 hi-res board. Note that to get to the board I had to first remove the factory-installed metal cover and inner shielding (yellow mylar?) that covered the hi-res board like an envelope. This is the view of the rear of the computer after these two covers were removed and after re-connecting the card to the computer for testing. Click on image for larger view.

When I first got this unit the hi-res board did not work. It turned out that the board was not plugged into the expansion connector correctly.

Note how RadioShack added a extension cable to the expansion port so one could still use this port for something else. That's the cable coming out from under the computer in the middle of this picture. The owner used this to connect his Exatron Stringy Floppy.

More Photos and the 26-1125 manual

  Space Invaders by Bill Degnan - 03/30/2015 15:27
Space Invaders for the hi-res board. Let me know if it works.

  Model III Graphics Image Generator by Bill Degnan - 08/09/2015 11:51

This looks like a great way to build up a library of images.

To get files to my TRS 80 Model III - I use my modern PC to optimize an image and upload to the web utility above to be converted. I take the BIN output file and move to a 3.5 disk. My IBM 5155 portable has 3.5" and 5 1/4" drives. Cross Zap is a PC utility that makes TRS 80 disks of various types, and allows the user to copy files. With this setup I can run the Cross Zap (XZ) utility to move the BIN file from the 3.5" IBM format disk to a 5 1/4" disk formatted by XZ for the TRS 80 Model III TRS DOS 1.3.

I boot up my copy of the TRS 80 TRS DOS 1.3 Computer Graphics disk and run the command...


I would still recommend using the FreHD but the method described above is "$free to me" being that I have everything on hand to do the job.

  Compatibility Issues by Bill Degnan - 08/19/2015 18:41
trs 80 Model III hi-res board distortion
Distorted image as displayed by my Model III.

Next - I have a problem with the way the software copies files from IBM PC format to TRS 80 Model III TRS DOS 1.3 SS format...need try a different machine. The file sizes are not correct. I tried covering the index hole, which allowed me to make it through the copy but not without errors.



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