Mumak wrote on 2022-02-18, 18:39:
Thanks. I will adjust this to report MDA instead, however on such really retro systems it's not possible to detect the exact adapter as it doesn't feature any registers that could be used for differentiation. I'm also not aware how to properly detect display memory size in this case.
Can you use this code?
http://www.pennelynn.com/Documents/CUJ/HTML/9 … ML/199001B5.HTM
If an MDA card is detected, however, you can also distinguish between an MDA card and the Hercules cards. To do this, the vertical sync bit is sampled and then for a certain time interval, is continually and frequently re-sampled. If no change is observed, the video card is assumed to be an MDA card. If the vertical sync bit changes, the video card is one of the Hercules graphics cards. The specific card is identified by examining bits 4-6 of the status port; a pattern of 001 indicates a Hercules Graphics Card Plus, a pattern of 101 indicates a Hercules In-Color Card, and any other pattern is a Hercules Graphics Card.