>>15599Also unaware that Microsoft didn't make anything note worthy. Disk operating systems was old hat by 1981, CP/M stood out because it offered portability of applications where software written for say CP/M on the Ti-99 would work on CP/M for the CP/M for the Osborne with little effort (as long as the program didn't directly address hardware). MS-Dos didn't offer this which is why you have somewhat PC compatibles like the Sanyo MBC-550.
As for Windows by the time the first version of MS Windows was released not only was there of course MacOS but the Amiga was released, AT&T Unix had gotten an official desktop, Tandy released Deskmate, Digital Research released GEM, IBM released Top View, and Quarterdeck released DESQView.