Discontinued operating systems

BESYS (Bell Operating System) was an early computing environment originally implemented as a batch processing operating system in 1957 at Bell Labs for the IBM 704 computer.

The ETA10 is a vector supercomputer designed, manufactured, and marketed by ETA Systems, a spin-off division of Control Data Corporation (CDC). The ETA10 was an evolution of the CDC Cyber 205, which can trace its origins back to the CDC STAR-100, one of the first vector supercomputers to be developed.

TRSDOS (which stands for the Tandy Radio Shack Disk Operating System) is the operating system for the Tandy TRS-80 line of eight-bit Zilog Z80 microcomputers that were sold through Radio Shack from 1977 through 1991. Tandy's manuals recommended that it be pronounced triss-doss. TRSDOS should not be confused with Tandy DOS, a version of MS-DOS licensed from Microsoft for Tandy's x86 line of personal computers (PCs).

UNIX/32V is an early version of the Unix operating system from Bell Laboratories, released in June 1979. 32V was a direct port of the Seventh Edition Unix to the DEC VAX architecture.

1990s UNIX coalition

operating system

microkernel operating system

operating system