IBM PCjr

It was thus said that the Great Jeff Hellige once stated: For the normal CGA modes, yes. But for the 320x200x16 and 640x200x4 no. For some reason, when in those modes, they did not appear at the standard CGA address in the IBM PCjr, which made programming for those modes on the PCjr real fun (gotta love the way MS-DOS can't deal with non-contiguous memory). In the PCjr, the video memory could reside anywhere in the first 128K of RAM, but there was circuitry to echo that to the standard CGA addresses. And due to the video memory sharing main memory, the PCjr wasn't as fast as the PC (that, and due to lack of DMA). When programming those modes under MS-DOS, I had to boot a particular setup where I knew the address of the video, which left me less memory to work with MS-DOS, since MS-DOS was loaded PAST the video memory (which if I recall, meant I lost something like 64 or 96K of RAM - oh, the video memory couldn't reside just anywhere, there were alignment restrictions. Sigh). -spc (Funny that the Tandy's were more compatible than the PCjr ... )