Early S-100 Graphics cards.
 

Matrox produced two early graphics cards, the ALT-256 and ALT-512. I have done up an article on these showing the graphics/images they were capable of displaying:

http://worldphaco.com/uploads/MATROX_ALT256.pdf

A couple of images attached. It was relatively easy to repair the cards, but more difficult to write the software to load the images. I have been running these in a SOL-20 computer.

Re: Early S-100 Graphics cards.
 

I enjoyed reading your clear and detailed write-up. Thank you for taking the time and trouble to share your adventure. I had no idea that Matrox had been around for so long.

I was intrigued to see that "clear all pixels" and "set all pixels" are apparently implemented in hardware. Can you explain how they work? I speculate that they jam 0 or 1 on the write port to all rams and somehow reuse the video readout address counters to cycle through writing all addresses during the course of one frame time.

Regards

Neal.

Re: Early S-100 Graphics cards.
 

It is a very useful feature to clear the screen before writing the image. I'll have a look a the schematic and see if I can figure out exactly how they did it, you are probably correct. The feature (bulk erase) is the same on both cards, but on the 512 you have to also select the plane register first.

Re: Early S-100 Graphics cards.
 

Interesting write up thanks!

The bulk clear is indeed interesting. I was amazed when I ported the BBC micro ROM how much trouble (and precious ROM space) was taken up with a fast clear screen routine.

D