[kragen]

I'm not sure I understand what you mean.

You probably remember Gary did start selling an MS-DOS clone (DR-DOS) after a few years, when it became clear CP/M-86 was dead. IIRC that's what inspired Microsoft to start working on MS-DOS again after several years of letting it languish. They also put anti-DR-DOS code into Windows so you couldn't start it up on DR-DOS.

And, as you know, there were a number of other bare-bones "operating systems" like MS-DOS and CP/M in those days: HDOS, TRS-DOS, ProDOS, etc. But once everyone was writing their apps for MS-DOS, there was little point in bringing out a new OS that wasn't compatible with it unless it was dramatically better in some way.

So, why weren't there other members of what set?

[WalterBright]

> there was little point in bringing out a new OS that wasn't compatible with it unless it was dramatically better in some way.

Make a free open source one.

[kragen]

We do have FreeDOS now! Someone could have written it in 01981, but, as I understand it, the ideological motivation for such activities wouldn't be articulated until Stallman founded GNU years later.