Hello,
I'm using various display tests programs and found what appears to be a bug in PCem's VGA write mode 0.
Testing the VGA "ALU" operations results in incorrect display :
Here the test consist of ANDing the CPU bytes (that pass through the "barrel shifter" and the "set/reset" logic) and the latches
It should be like this :
Interestingly enough if I remove operation with the latches, display is correct. But that is not the right workaround : maybe the latches values read before are wrong ?
Config Used :
PCem v14 - latest source code compiled under msys2
AMI WinBIOS 486 - NO dynamic recompiler
8 Mb RAM
Cirrus Logic GD5429
No Sound
CD-ROM 4x - 256 Mb IDE Hard Disk
Serial Mouse - No Network
DOS 6.22
VGA write mode 0 display bug
VGA write mode 0 display bug
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- SarahWalker
- Site Admin
- Posts: 2054
- Joined: Thu 24 Apr, 2014 4:18 pm
Re: VGA write mode 0 display bug
Is the test program you're using here something you can provide? (ie without posting copyrighted material to the forum...)
Re: VGA write mode 0 display bug
Hello,
I think the program is copyrighted (at least that's what the program displays when I launch it) and the company is still alive.
Can I send you this by another mean ?
Regards.
I think the program is copyrighted (at least that's what the program displays when I launch it) and the company is still alive.
Can I send you this by another mean ?
Regards.