Although PC-98 was not PC-compatible, Microsoft did support it in DOS and Windows. Programs that just went through DOS or Windows and didn't make lower level BI

Although PC-98 was not PC-compatible, Microsoft did support it in DOS and Windows. Programs that just went through DOS or Windows and didn't make lower level BIOS calls directly or try to manipulate hardware directly would frequently just work out of the box on PC-98. The biggest difference between PC-98 and PC compatibles the DOS/Windows didn't hide that I remember, and that I remember being the biggest source of DOS/Windows programs failing even if they weren't doing low level calls was drive letter assignment. On PC-98 A: was the drive you booted from. If your system had a floppy drive and a hard drive, and you booted from hard drive then A: would be your hard drive. B: would be your floppy. In a PC-compatible A: would be the floppy and C: would be the hard disk regardless of which of the two you booted from. Quite a few programs turned out to have "C: is the first hard drive" hard coded in.