MDA and CGA were controlled by the 6845, so I suppose this applies to MCGA too.
So it is just a matter to set up the 6845 register configuration to get what you want (provided the monitor can take it).
Beware that the original IBM monochrome monitor gets killed very easily if you apply wrong horizontal clocks.

Try to find a copy of the book Zen of Graphics Programming by Mike Abrash, he has some pages on Mode X which I used back in the day to get some exotic resolutions. The closest I can find just looking quick is 640x350, but I think it's 1bpp 😒

also try:
http://nerdlypleasures.blogspot.com/2014/09/o … tions-when.html

is mode 12h not acceptable? 640x480x16?

good luck! just looking at the cover takes me right back to when I was 16 listening to Pretty Hate Machine and cranking out assembly code all hours of the night 😀

I'm speaking under correction, but I believe that MCGA was somewhat restricted in several ways. No EGA modes, for example.
Some VGA games in 320x200 refused to work on MCGA also. I wonder if MCGA's palette was "set in stone" or as flexible as that of VGA.

Also an interesting read - https://trixter.oldskool.org/2017/10/01/the-f … -on-the-ibm-pc/

By the way, some tools like NSSI have the ability to search for undocumented screen modes.
Not sure if these are useful in this case, but it shouldn't hurt trying them on a real MCGA machine.

Jo22 wrote:

I'm speaking under correction, but I believe that MCGA was somewhat restricted in several ways. No EGA modes, for example. Some […]
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I'm speaking under correction, but I believe that MCGA was somewhat restricted in several ways. No EGA modes, for example.
Some VGA games in 320x200 refused to work on MCGA also. I wonder if MCGA's palette was "set in stone" or as flexible as that of VGA.

Also an interesting read - https://trixter.oldskool.org/2017/10/01/the-f … -on-the-ibm-pc/

By the way, some tools like NSSI have the ability to search for undocumented screen modes.
Not sure if these are useful in this case, but it shouldn't hurt trying them on a real MCGA machine.

Awesome read about the MCGA games! I think the palette registers were already there for the MCGA.

Also previously mentioned 640x480 mode would be monochrome on the MCGA due to it only having 64KiB framebuffer.

After more searching I found a discussion thread on github https://github.com/joncampbell123/dosbox-x/issues/777

It looks like it is closer to CGA with some extra capabilities hardwired in the chip, while missing the many options/flexibility of VGA. I'm still wondering what might be possible along the lines of the CGA "160x100" hacked character mode (with different font?). Or messing with other registers while the bits are set for 8bpp or 640x480 mode (or both at the same time?). Too bad I don't have a real MCGA system to experiment on. There is a link in the thread to a digital copy of a book covering the video hardware which I haven't looked at yet.