RE: "I have heard of (but not seen) machines with 8" floppies that run
MS-DOS 1.x (not real sure what version)."
Well, the Heathkit / Zenith Z-100 ran MS-DOS (called Z-DOS -- it was not PC
compatible at the hardware level) and also supported 8" floppy drives (in
fact a very nice accessory external dual-drive 8" floppy was offered).
Also, again not PC compatible, but the CompuPro (Godbout) systems had 8"
drives and in some configurations ran MS-DOS. Also, the Seattle Computer
Products systems. And there were 8" controllers for early PCs.