Main

CTSS (The Compatible Timeshare System, developed at MIT by Corbato, et al)
Incompatible Timesharing System (ITS, developed at MIT for the DEC 10 / 20 mainframes)
THE multiprogramming system (by Dijkstra et al.)
Multics (joint OS development project by Bell Labs, GE, and MIT)
Master programme (developed forLeo Computers, Leo III in 1962)
RC 4000 Multiprogramming System (developed by Regnecentralen in 1969)

Apple Computer Apple DOS (initial version was Read-only memory firmware together with Integer BASIC; later versions included a Microsoft BASIC)
Business Operating System (BOS) - cross platform, command-line based
Commodore PET, Commodore 64, and Commodore VIC-20,
The very first IBM-PC (3 OS offered to start, UCSD p-System, CP/M-86, PC-DOS)
Sinclair Micro and QX, etc
TRS-DOS, NEW-DOS, ROM OS's (largely Microsoft BASIC implementations with file system extensions)
TI-99/4A
Flex (by Technical Systems Consultants for Motorola 6800 based microcomputers: SWTPC, Tano, Smoke Signal Broadcasting, Gimix, etc)

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