I really don't know.
I though 800x600 was only possible with 16 colors (256 KB) but I also though that 640x480 256 (512 KB) was possible, so I am wrong in one of them (or both).

I have configured PCem with the card and installed Windows 3.1 with the drivers provided by tayyare: Re: Wanted Diskette Drivers for OTIVGA OTI067 card
They support weird resolutions (768x1024) but they don't support 640X400.

ntalaec wrote on 2020-03-09, 21:30:

I though 800x600 was only possible with 16 colors (256 KB) but I also though that 640x480 256 (512 KB) was possible, so I am wrong in one of them (or both).

You may also be perfectly right.
I've seen at least one 512 KB card that can't do 800x600x256.
I'm not sure why - perhaps not enough video memory bandwidth?

Did somebody manage to run PVGA1A-JK 640x480x256 with UniVBE?

I have a strange problem. My videoadapter is detected by UniVBE as 512K even though it has only 256K of RAM. Also, I don't have an option to use 640x480x256 mode, only low-resolution ones (the biggest is 320x480 if memory serves). And these modes are not available on my LCD display (frequency problems?)

Installation of additional RAM changes nothing (only lowest part of the scrollable image appears, for sure).

So the questions are:

- why UniVBE cannot detect proper amount of memory? Does it work at all with 256K cards?
- how can I enable 640x480x256 under DOS with this card?

Oh, that's really strange. When I run uvconfig with -m256 param forcing detection of 256KB of memory it said it wouldn't work at all as the card is not supported. While running it again without any params it said that there are 10 modes now supported instead of 6 and 640x400(480) appeared. Interesting.

Forget UniVBE, I think it's Vaporware, it won't work properly with many sophisticated applications.
At least not in combination with early ISA VGAs. Had little else than trouble with it.

UNIVBE 4.0 and old hardware

Instead, please try the old VBE utilities. They're very limited, but they do provide what they claim to support, at least.
And programs won't crash or do funny things when they're running.

Re: OAK OTI-037c - 800x600 mode ?

Jo22 wrote on 2022-09-11, 12:32:

Forget UniVBE, I think it's Vaporware, it won't work properly with many sophisticated applications.
At least not in combination with early ISA VGAs. Had little else than trouble with it.

It helped me a lot when I had PCI videocard (DSV6422), that was "upgraded" from VBE 1.2 to VBE 3.0. I liked additional modes and VBE/AF extensions. As for ISA cards, I suppose, they could not help much so did not even bother.

Thanks, I'll try searching for some native DOS drivers. I don't need much on my 386 build, probably 640x480 is more than enough.