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Implmenting VESA on IBM XGA-1 on P75 with LCD Monitor

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First post, by uscleo

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Hi! I have been restoring a P75 and I have pretty much got it running so I have been trying to run some games on it. The P75 has a built in XGA-1 type card for graphics (drives both the internal VGA monochrome 16 shade plasma display, as well as the external VGA at 256 colors) which works well runnng Windows 95. Using the latest XGA drivers, I have been able to run Windows 95 at 16 bit color, but I have been running into problems with late-dos games.

In particular, it seems that the XGA-1 is not nativly VESA compliant, requiring the use of XGA212.exe - a file I found here http://ohlandl.ipv7.net/video/XGA1.html The disk comes with some setup instructions on how to load drivers for XGA in config.sys and autoexec.bat, but the game I am trying to run still won't load, giving "no vesa driver found" errors. Then there is a folder in the XGA212 called Vesa and in there there are executibles which emulate vesa compatibility - running the game after running the program (called VGAVESA or soemthing similar) allows the game to load but the color palette is broken - greens show up as orange, etc - picture is fine, and so is resolution, but the color almost looks inverted. Anyone have any ideas on what to try?

Reply 1 of 4, by Jo22

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Not 100% sure, but wasn't there an issue with 15-Bit vs 16-Bit colour depth ? Or was it about VESA 1.2 vs VESA 2.x ? Sorry, can't recall. 🙁
Just vaguely remember that there was a tool that did hide some VESA features in order to make some DOS games happy.

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Reply 2 of 4, by G B

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There is an .exe file I have seen called XGAPAL.EXE

It corrects the color issue that you describe. Last place I saw it was in the VESA\IBM folder of a DOS install for SimCity 2000.

Reply 3 of 4, by dr.zeissler

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G B wrote on 2021-10-20, 22:16:

There is an .exe file I have seen called XGAPAL.EXE
It corrects the color issue that you describe. Last place I saw it was in the VESA\IBM folder of a DOS install for SimCity 2000.

Yes indeed, there is such a file in the VESA - IBM Folder of the SC2000 network edition.
I don't know if it fixes SC2000 on XGA Vesa but it defenetly does not fix XGA2 on MCA or ISA for things like image-viewer like quickview102.
Beside that the IBM xga2-vesa driver does not offer 1024 resolution and nothing more than high color, but XGA2 does true color.
The IBM Win30 driver seems also be affected by the color issue. Try loading true-color images with paintbrush30 on windows30a with 640x480x16M colors.
The only image viewer under dos that does XGA mostly correctly is GWS7. It struggles with 800x600 though (some doubled lines on the bottom).
And 1024 does not work (blank-screen perhaps 43hz monitor-setting and the other settings are ignored, seems to be hardcoded) but 640x480 works fine without the broken colors.

Retro-Gamer 😀 ...on different machines

Reply 4 of 4, by dr.zeissler

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I have to correct myself. XGA2 on MCA bus is working in some circumstances, but that does not count for XGA2 on ISA bus for PS/2E. So show 8.3 and GWS7 fail on XGA2 on ISA bus. SC2000 and Links386 still fail on everything. What is the BiosFlag to start them?

Retro-Gamer 😀 ...on different machines

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