[musicale]

> I think virtually all of its major design decisions were mistakes, except for the BIOS/BDOS split, though not such serious mistakes as to make it completely unusable. I'm interested to hear why you disagree so strongly.

"Pretty good" isn't the same as "perfect". All of your comments seem completely reasonable. But that BIOS/BDOS design made CP/M a minimum viable portable OS that enabled binary software portability and created an ecosystem across 8-bit hardware from many vendors (not to mention homebrew), starting in 1974. The closest things to it in that space were Microsoft BASIC (with many incompatible versions) and the UCSD p-System, as you note. So I rate CP/M "great" in terms of its industry innovation – specifically how it applied technology to develop a successful 8-bit PC compatibility standard, providing a model for the 16-bit era of DOS and IBM PC compatibles.

Years later, Linux seems to be stuck with multiple, incompatible formats for binary software packaging (snap, flatpak, appimage, docker, win32...) Though I guess you don't have to worry about different sizes of floppy disks.