it was indeed one bad bios, along with at least one drive of questionable integrity, and i'm irritated i spent so much time with it. there wasn't a way to reset the cmos, but a "set to default" got the floppy working properly in freedos. sort of. it's still sketchy. i'm going to have to flash...

first, to find a disk that i can actually format. i'm confident that this should get the main pc's bios in.