Hello Ruud, > Solved one problem, bumped into another one. When you insert a 16-bit > card it tells the PC by negating MEMCS16. It does this by decoding > A17..A23. This is a 128 KB range. So adressing the $Cxxxx range = > CGA and MDA, this line is activated AFAIK. So this als must happen if a > MDA card is inserted. Now see next table: I can remember *for sure* that I once had an 8 bit Hercules (expanded MDA) and a 16 bit VGA card (ET4000) on my 286 (and later 386) PC. I used them for debugging purposes (output on one screen, debugging output on the other). I always wandere why the VGA was so much slower with the Hercules inserted; if I removed the Hercules card, it was much faster! I then found out (with the diagnostics software of the VGA) that the VGA was made 8 Bit by Software when the Hercules was inside; else, it was 16 bit. I then stripped the code for changing 8/16 bit into an own program, thus putting the VGA 16 bit on boot. In this case, the MDA did not display anything, it just frooze its contents. When I wanted to use both card, I put the VGA on 8 bit. When I was done, I reverted to 16 bit. In this case, the display on the hercules freezed. So, that I wanted to tell you: From this experience, I'm quite sure that when MDA is inserted, the $Cxxx range is just used as 8 bt, MEMCS16 is not negated. So you don't have to handle that case IMHO. Spiro. - This message was sent through the cbm-hackers mailing list. To unsubscribe: echo unsubscribe | mail cbm-hackers-request@dot.tml.hut.fi.
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