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Thread: Matrox graphics on my sol-20

  1. #1

    Default Matrox graphics on my sol-20

    I have been trying out a vintage MATROX S-100 graphics card in my SOL-20 running 48k CP/M.

    I started out with a 180kB .bmp graphics file, far too big for the SOL, took it across to my IBM5155 and wrote some small .exe's (8088 assembly language & MASM) to crunch the bytes and compress and format the files. Later sent these files to the SOL using PCGET and figured out how to get them from disk to memory where I processed them further with an 8080 assembly language program & ASM, to load the Matrox 's RAM, it requires a two plane image (the 4 shades of grey are possible because of the two planes which are simultaneously displayed with different weighting).

    Since I'm only just learning assembly language it took a while to get it right and no doubt my code could be more efficient. The initial image I started with had a little too much contrast, I'm preparing a better one now. And I'm writing up an article to explain how it was done (the first step was repairing the faulty card).

    I have attached a photo of the image on the VDU face that came up last night, it was a really great thing to see after all the byte crunching. Probably this card had not produced an image or graphic since the 1970's.
    Attached Images Attached Images

  2. #2
    Join Date
    Oct 2011
    Bedford, NH, USA


    Excellent! Well done! Thanks very much for sharing. I'll be looking forward to read your article.

    Do you have a Matrox ALT-256 or a Matrox ALT-512?

    I'd really love to get a hold of one of those!


  3. #3


    Quote Originally Posted by smp View Post
    Excellent! Well done! Thanks very much for sharing. I'll be looking forward to read your article.

    Do you have a Matrox ALT-256 or a Matrox ALT-512?

    I'd really love to get a hold of one of those!

    The ALT256 just has a single plane with on-off pixels, you can still do amazing things with that with line drawings etc. For those if you combine 3 cards you can have an 3 bit, 8 shade of grey or RGB color system.

    The ALT512 , the one that produced the image I posted, has enough memory for two planes, and they can be combined in a number of ways . The B plane has half the analog video weighting of the A plane so combining it with the A plane gives 4 possible output levels from the one card, black, dark grey, light grey and white, which is how that image was possible from just the one card. It would have taken two ALT256 cards to do it the same.

    Matrox made some fairly elaborate demonstration software for the ALT256, I'm planning to assemble that when I can. I couldn't find much on the 512, but it can behave like the 256 if the correct registers are used. I have the 256 card too and it will be featured in the same article with some information that helps to repair it, for example a pixel vs physical IC map useful in fault finding.

    (The source of the original image is interesting, was a jpeg I had in my files. It was a camera photo of a VDU(monitor) face of a still frame from a DVD, that I had after I wrote an article on a very unusual video monitor made by Conrac for some sort of military airborne radar application, the original photo is on about page 21 of this article: , if you want to see the world's best made monochrome video monitor, this is certainly it)
    Last edited by Hugo Holden; July 22nd, 2019 at 02:48 PM.

  4. #4


    I modified the original image contrast scale of the image which improved the final result after my compression software gets it down from about 180kB to 7.5kB per plane. When the pixels from the two planes are combined with the two level weightings, they can also be plotted on top of each other or interleaved, an example of both is shown in the attached photos, in one case the individual pixels are more easily visualized.
    Attached Images Attached Images


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