multiple CGA cards on ISA bus?

THe answer is 'no' if you're talking about standard CGA cards. The CGA card takes up a block of memory space for the video memory (16K IIRC), and a number of I/O port addresses for things like the status register , 6845 CRT controller, etc. On a standard CGA card the addresses of all that stuff is fixed in hardwree, so obviously if you put 2 cards into the same machine there's no way to select them independantly. The manuals you want are the IBM PC Technical References. Either an old-version PC, XT, or AT TechRef (which cover the expansion cards as well), or the Options and Adapters Techref (which certainly convers the CGA card). That will include full schemaitcs of the card, along with programming info, etc. The ISA bus is very similar to the 8088 bus, so an Intel databook and the motherboard scheamtics (in the system techrefs) will help there. And the system techrefs also include BIOS source listings (including the CGA driver routines). Unforutnately I have no idea where to find this stuff now ('On the bookshelf at the top of the stairs', while true, is not helpful to you). -tony