Re: EGA FLAND maps 0/1 loading issues in UniPCemu

Posted on 2024-02-24, 16:38

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by GloriousCow

in PC Emulation

in PC Emulation

Does it instruct MS-DOS to write directly the read file contents into VRAM? I see lots of INT 21h function AX=1A1Ah followed by INT 21h function AX=2121h (memory at DS:BX=2)? Yes, it does. It sets the map mask register to isolate the appropriate plane, then Int 21h 3F to read two blocks of 8000h …

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Re: EGA/VGA programming differences and incompatibilities

Posted on 2024-02-24, 16:16

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by GloriousCow

in PC Emulation

in PC Emulation

Congrats!

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Re: EGA FLAND maps 0/1 loading issues in UniPCemu

Posted on 2024-02-24, 16:12

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by GloriousCow

in PC Emulation

in PC Emulation

Nothing special that I can see - but I suspect you might be making some assumptions about text mode. Normal text mode puts the CRTC in word mode, with the sequencer and graphics controller in Odd/Even mode FLAND puts the CRTC in byte mode, and the sequencer and graphics controller are set for …

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Re: EGA/VGA programming differences and incompatibilities

Posted on 2024-02-23, 13:48

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by GloriousCow

in PC Emulation

in PC Emulation

Well, my Mode F needs some work, but I can see a smooth sinus pattern with the pel panning, just like the melt demo.

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Re: EGA/VGA programming differences and incompatibilities

Posted on 2024-02-23, 02:13

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by GloriousCow

in PC Emulation

in PC Emulation

Is Mode F supposed to use the 14Mhz clock?

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Re: EGA/VGA programming differences and incompatibilities

Posted on 2024-02-22, 18:43

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by GloriousCow

in PC Emulation

in PC Emulation

I implemented pel panning as a fundamental operator of the Attribute Controller. There's nothing to 'latch' per se; when you write a new value to the attribute controller's pel panning register it takes effect immediately. If you maintain a two-character / 16 pixel FIFO, then you can just shift the …

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Re: EGA/VGA programming differences and incompatibilities

Posted on 2024-02-22, 18:30

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by GloriousCow

in PC Emulation

in PC Emulation

melt (game.exe) in MartyPC: Filename melt_02.gif File size 1.43 MiB Views 1045 views File comment MELT effect in MartyPC (click for animated version)

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Re: EGA/VGA programming differences and incompatibilities

Posted on 2024-02-21, 14:31

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by GloriousCow

in PC Emulation

in PC Emulation

Just have been thinking... UniPCemu latches pixel shift count and byte panning (which are combined) on vertical retrace end (pixel shift count) and vertical retrace start (byte panning). Are those even latched? Or always live? Byte panning btw is counted as pixel shift count addition measured in …

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Re: MartyPC

Posted on 2024-02-19, 13:37

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by GloriousCow

in PC Emulation

in PC Emulation

Afaik it depends on the pixel mode. During 8 pixel character clocks it MOD 7. So 8-F=0-7. During 9 pixel character clocks 8=0, 0-7=1-8. Above 8 is undocumented. I simply made it 0 there. Perhaps it aliases 1-8 to 9+? You'd need to check real hardware on that. Have you tried FantasyLand in UniPCemu?

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Re: MartyPC

Posted on 2024-02-18, 21:36

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by GloriousCow

in PC Emulation

in PC Emulation

FantasyLand doesn't seem to use pel panning, which is interesting. It uses the preset row scan register for smooth vertical scrolling, but horizontal scrolling appears character based. Hmm - I'll admit that I was lazy and only looked it up on youtube (https://www.youtube.com/watch?v=czfGt5iNuSQ), …

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Re: MartyPC

Posted on 2024-02-18, 19:01

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by GloriousCow

in PC Emulation

in PC Emulation

FantasyLand doesn't seem to use pel panning, which is interesting. It uses the preset row scan register for smooth vertical scrolling, but horizontal scrolling appears character based. Just curious, how do you handle the monitor's borders? I get weirdly sized black borders on top,bottom,left,right …

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Re: MartyPC

Posted on 2024-02-18, 14:54

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by GloriousCow

in PC Emulation

in PC Emulation

FantasyLand doesn't seem to use pel panning, which is interesting. It uses the preset row scan register for smooth vertical scrolling, but horizontal scrolling appears character based.

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Re: MartyPC

Posted on 2024-02-18, 12:49

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by GloriousCow

in PC Emulation

in PC Emulation

I'm pretty sure FantasyLand does that. It should be a good text mode torture-test in general, although it expects the EGA to be switched to 15.7KHz-only operation (i.e. 200-line text modes). PCjs made a big deal of being able to run it, although it gets the color palette glaringly wrong. :) It runs …

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Re: MartyPC

Posted on 2024-02-17, 21:51

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by GloriousCow

in PC Emulation

in PC Emulation

EGA support is coming along well. The EGA emulation is character-accurate and the various duties of the various LSI chips are simulated. A similar strategy has been used for EGA as was used for MartyPC's CGA - one of two fixed resolution fields are scanned out (depending on whether the EGA is …

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Re: Emulating smooth scrolling in EGA - SOM + Pel panning?

Posted on 2024-02-15, 12:35

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by GloriousCow

in PC Emulation

in PC Emulation

keenmaster486 wrote on 2024-02-15, 04:40: I think there's been discussion about this before with reference to clone EGA cards not scrolling Commander Keen correctly. Because they latch the start address at a different time?

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Re: Emulating smooth scrolling in EGA - SOM + Pel panning?

Posted on 2024-02-15, 01:11

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by GloriousCow

in PC Emulation

in PC Emulation

Well, as soon as I post this, I find this thread: https://www.vogons.org/viewtopic.php?t=57320 Changed from latching the start address at vertical total to latching it at vsync, and now the scrolling is smooth. Imagine that. Would still love to know what the heck the SOM bit is supposed to do, …

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Emulating smooth scrolling in EGA - SOM + Pel panning?

Posted on 2024-02-14, 23:36

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by GloriousCow

in PC Emulation

in PC Emulation

I'm confused about the SOM field in the End Horizontal Retrace Register. Ferraro has this to say about it: Determines whether an odd or even memory address should be used as the first memory address after a horizontal refresh =0 Start at an even memory address =1 Start at an odd memory address IBM's …

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Re: EGA/VGA and mode Fh mono 'colors'?

Posted on 2024-02-11, 20:31

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by GloriousCow

in PC Emulation

in PC Emulation

superfury wrote on 2024-02-11, 00:20: GloriousCow wrote on 2024-02-10, 23:44: Can you post your test utility? I can see if it blinks on hardware, if you haven't tested that. https://bitbucket.org/superfury/unipcemu/src/ … niPCemu/pascal/ You'll need UNIPCEMU.PAS and MODE0F.PAS. I was hoping you …

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Re: EGA/VGA and mode Fh mono 'colors'?

Posted on 2024-02-10, 23:44

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by GloriousCow

in PC Emulation

in PC Emulation

Can you post your test utility? I can see if it blinks on hardware, if you haven't tested that.

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Re: EGA/VGA and mode Fh mono 'colors'?

Posted on 2024-02-10, 14:50

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by GloriousCow

in PC Emulation

in PC Emulation

It's both inverted and reverted if I'm using the proper terms. On=0, off=1 (=inverted) clock #0=SW#3 and clock #3=SW#0 (=reverted) Otherwise, the IBM documentation on the switches and resulting table entries doesn't match the monochrome modes properly (not selecting 3Bx or aborting in some cases)? …

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