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Thread: M4 pixels not all the same size. really?

  1. #21
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    Quote Originally Posted by pski View Post
    They all use essentially the same port driven API for the hires board. Other than memory origination, only the keyboard, file and serial i/o routines would need to change.
    Barely on-topic for this thread, I have a quick dumb question (two-parter) about TRS-80 Hi-Res board(s), or at least a specific type of them. (I've been digging around for docs and so far it's a little thin on the ground.) First: it looks like there's at least two fundamentally different kinds of Model III/4 high-res boards? I see references to:

    A: The "original" Grafyx Solution for the Model III, which is memory mapped and completely different from the later boards?

    B: Later Microlabs and Radio Shack boards, which use a port-based API to access individual memory bytes and are more-or-less compatible with each other?

    And part 2: Is there any significant amount of software that's compatible with the "Type A" boards? (And more complete documentation for them?) Reason I ask is I'm slowly plugging away on an idea for making a cheap and cheerful design for a memory-mapped video card designed to roughly duplicate various early S100 and Tandy video systems while also offering full-screen pixel graphics modes, and from that brief description I linked to above emulating the "old style" Model III Grafyx board would be pretty trivial (except for text overlay) since I was planning to make the memory page-able within a 1k window anyway.

    Or is the Model III Grafyx enough of an odd man out that it's not really worth bothering?
    My Retro-computing YouTube Channel (updates... eventually?): Paleozoic PCs

  2. #22
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    I've not heard of anyone having the early Grafyx Model III boards. And have not run into software that uses them. So I'd say they're not worth bothering about.

    Micro-Labs and others made programmable character generator graphics boards for the Model I and Model III. They're relatively more common and may be of interest to you but I feel like I'd be hard pressed to round up more than 20 programs that use them. However, modern MSIE expansion board supports programmable character graphics so some modern software does use it.

  3. #23
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    I really wish I could find the manual for the Model III Grafyx solution nonetheless. TRS-80.com has a scan of the cover but I can't find the actual document *anywhere*.
    My Retro-computing YouTube Channel (updates... eventually?): Paleozoic PCs

  4. #24
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    Quote Originally Posted by Eudimorphodon View Post
    I really wish I could find the manual for the Model III Grafyx solution nonetheless. TRS-80.com has a scan of the cover but I can't find the actual document *anywhere*.
    Is the scan on Ian's website what you're after?

    http://members.iinet.net.au/~ianmav/hires/hires.htm
    See "INSTRUCTION MANUAL PDF" under "Grafyx Solution Software - GBASIC - Model III (came with µLabs board)"

  5. #25

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    I'm pretty sure Mav at one time sold a MIII Grafyx solution replica. Ask him if he still has any on hand.

  6. #26

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    Quote Originally Posted by gp2000 View Post
    I've not heard of anyone having the early Grafyx Model III boards. And have not run into software that uses them. So I'd say they're not worth bothering about.

    Micro-Labs and others made programmable character generator graphics boards for the Model I and Model III. They're relatively more common and may be of interest to you but I feel like I'd be hard pressed to round up more than 20 programs that use them. However, modern MSIE expansion board supports programmable character graphics so some modern software does use it.
    An example of PCG-80 support for the Model I in the MISE

    IMG_0633-300x225.jpg

  7. #27
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    Quote Originally Posted by gonk23 View Post
    Is the scan on Ian's website what you're after?

    http://members.iinet.net.au/~ianmav/hires/hires.htm
    See "INSTRUCTION MANUAL PDF" under "Grafyx Solution Software - GBASIC - Model III (came with µLabs board)"
    Thanks! I guess I did see that and assumed it was only documentation for GBASIC, but it turns out it has the information I was looking for regarding the memory organization of the paging system. (TL;DR, the Grafyx Model III's 12 screen pages correspond with the character row addresses. If you think CGA's 2-way interlacing in graphics mode is fun just hold onto your hat, the Grafyx Model III has *twelve way* interlacing.)

    Replicating the graphics/text overlay would be a challenge without adding a second RAM chip. Possibly not an insurmountable one, need to think on that.
    My Retro-computing YouTube Channel (updates... eventually?): Paleozoic PCs

  8. #28
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    Quote Originally Posted by Eudimorphodon View Post
    Thanks! I guess I did see that and assumed it was only documentation for GBASIC, but it turns out it has the information I was looking for regarding the memory organization of the paging system. (TL;DR, the Grafyx Model III's 12 screen pages correspond with the character row addresses. If you think CGA's 2-way interlacing in graphics mode is fun just hold onto your hat, the Grafyx Model III has *twelve way* interlacing.)
    I'll second that thanks! I didn't realize information was available on it.

    Should be fairly easy to implement in trs80gp. It's also a fascinating midpoint between their programmable graphic character boards and the Tandy-compatible (mostly) bitmap boards. The PCG version uses a similar re-use of the screen memory locations but instead of writing into bitmap RAM they writing into a character generator. Nifty.

  9. #29
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    The organization makes perfect sense, given it lets them just tack onto the Model III's existing row counter chain. It's no worse than any number of other machines, I suppose. (The Apple II hi-res mode, for instance, is pretty whack.) Perfectly linear framebuffers were more the exception than the rule back in the day.
    My Retro-computing YouTube Channel (updates... eventually?): Paleozoic PCs

  10. #30

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    I bought one of the cards from Ian (well just the board) and its sitting somewhere in the parts bin pigtails and all - That thing needed pigtails all over the damn place.

    Once it was working it was a huge disappointment to find that hardly anything worked with it. I got the RS repro board from him for my III and slapped it togther stole a CRTC from a Model 4P I think and it works fine with the RS Stuff for me. I use the repro 4 hi res cards in two Model 4s and I've not found anything that didnt work (a few patched programs needed). The only thing I dont like is that the III screen is squished a bit to keep the Hi Res from overscanning- which is just how it is. I use the 4P the most for hi res stuff, mainly because of where its sitting and play a few games on it when doing something crazy like installing Xenix Developer Kit.

    Now onto your speed thing, the SLOT machine program on the 4 hi res card is pretty good for moving the images around to look like a spinning wheel x 3. Dog Catcher is kinda a good example of it.

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