TOPS-10 System (Timesharing / Total Operating System-10) is a discontinued operating system from Digital Equipment Corporation (DEC) for the PDP-10 (or DECsystem-10) mainframe computer family. Launched in 1967, TOPS-10 evolved from the earlier "Monitor" software for the PDP-6 and PDP-10 computers; this was renamed to TOPS-10 in 1970.
The TOPS-10 operating system was designed to be primarily a time-sharing system, and supported "time sharing, remote batch processing, multiprogrammed batch, real-time, and multiprocessor configurations."
TOPS-10 supported shared memory and allowed the development of one of the first true multiplayer computer games. The game, called DECWAR, was a text-oriented Star Trek-type game. Users at terminals typed in commands and fought each other in real time. TOPS-10 was also the home of the original Multi User Dungeon, MUD, the forerunner to today's MMORPGs.
Another groundbreaking application was called FORUM. This application was perhaps the first so-called CB Simulator that allowed users to converse with one another in what is now known as a chat room. This application showed the potential of multi-user communication and led to the development of CompuServe's chat application.
TOPS-10 featured an application programming interface (API) that used a mechanism called a UUO or Unimplemented User Operation. UUOs implemented operating system calls in a way that made them look like machine instructions. The Monitor Call API allowed developers to use these operations, for system programming on DECsystem-10s..
The TOPS-10 scheduler supported prioritized run queues, and appended a process onto a queue depending on its priority. The system also included User file and Device independence.
The following list of commands are supported by TOPS-10.
The PDP-6 Monitor software was first released in 1964. Support for the PDP-10's KA10 processor was added to the Monitor in release 2.18 in 1967. The TOPS-10 name was first used in 1970 for release 5.01. Release 6.01 (May 1974) was the first TOPS-10 to implement virtual memory (demand paging), enabling programs larger than physical memory to be run. From release 7.00 onwards, symmetrical multiprocessing was available (as opposed to the master/slave arrangement used before). The final release of TOPS-10 was 7.04 in 1988.
Hobbyists are now entitled to set up and use TOPS-10 under a Hobbyist's License.
The easiest way for the hobbyist to run TOPS-10 is to acquire a suitable emulator and an operating system image. TOPS-10 may also be generated from archived original distribution "tapes".
Paul Allen maintained several publicly accessible historic computer systems, including a DECsystem-2065 running TOPS-10.
Implemented programming languages
The TOPS-10 assembler, MACRO-10, was bundled with the TOPS-10 distribution.
The following programming languages were implemented on TOPS-10 as layered products:
ALGOL, as ALGOL-10 v10B, a compiler used for general computing
APL, as APL-SF V2, an interpreter used for mathematical modelling
BASIC, as BASIC-10 v17F, an interpreter used for general computing
BLISS, as BLISS-10 and BLISS-36, compilers used for systems programming