|Developer||Digital Equipment Corporation|
|Written in||ALGOL, BASIC, FOCAL, Fortran D, PAL-D|
|OS family||DEC OS family|
|Source model||Closed source|
|Latest release||8.24 / February 1975 |
|Kernel type||Time-sharing operating systems|
|Default user interface||Command line interface|
TSS-8 is a discontinued little time-sharing operating system co-written by Don Witcraft and John Everett at Digital Equipment Corporation in 1967. The operating system ran on the 12-bit PDP-8 computer and was released in 1968.
Don Witcraft wrote the TSS-8 scheduler, command decoder and UUO (Unimplemented User Operations) handler. John Everett wrote the disk handler, file system, TTY (teletypewriter) handler and 680-I service routine for TSS-8.
Roger Pyle and John Everett wrote the PDP-8 Disk Monitor System, and John Everett adapted PAL-III to make PAL-D for DMS. Bob Bowering, author of MACRO for the PDP-6 and PDP-10, wrote an expanded version, PAL-X, for TSS-8.
This timesharing system:
was based on a protection architecture proposed by Adrian Van Der Goor, a grad student of Gordon Bell's at Carnegie-Mellon. It requires a minimum of 12K words of memory and a swapping device; on a 24K word machine, it could give good support for 17 users.
Each user gets a virtual 4K PDP-8; many of the utilities users ran on these virtual machines were only slightly modified versions of utilities from the Disk Monitor System or paper-tape environments. Internally, TSS-8 consists of RMON, the resident monitor, DMON, the disk monitor (file system), and KMON, the keyboard monitor (command shell). BASIC was well supported, while restricted (4K) versions of FORTRAN D and Algol were available.
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