One more

on open personal affordable computing. CP/M86, which everybody thought to become the standard OS for the Intel side of the micropocessor world was not ready when IBM came looking for it in 1980, DRI did not sign IBM's non-disclosure agreement and it's probably true that Gary Kildall snubbed them. Before that the non-availability of CP/M86 hat lead Seattle Computer Systems to have one Tim Patterson write a stripped down CP/M clone for 8086. PC-DOS 1.0 that came from it felt a lot like CP/M and was, as we hear, slower, had fewer features but cost $60 vs. $240 for CP/M86 when it came out a little after. Interestingly MS-DOS 2 seems to have been a nearly complete rewrite modeled more after Unix (Xenix) and conceived by Paul Allen, who believed, only we know that MS didn't go or get very far in this. CP/M had been modeled more after a DEC OS for PDPs, probably TOPS-10 or -20. Application side in the PC world this was the time of SW like Lotus 123 that was tightly knitted to HW and full of tricks and outperformed everything else in its day but had its downfall of later built in with that. Now in terms of OSes funnily from version 2 on MS-DOS helped a lot to make the Unix style of computing including C win out over others in the world of small computers.