TOPS-10

The TOPS-10 System (Timesharing / Total Operating System-10) was a computer operating system from Digital Equipment Corporation (DEC) for the PDP-10 (or DECsystem-10) mainframe computer launched in 1967. TOPS-10 evolved from the earlier "Monitor" software for the PDP-6 and -10 computers; this was renamed to TOPS-10 in 1970.

Overview

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.

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 multiuser communication and led to the development of CompuServe's chat application.

TOPS-10 had a very robust 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 was very much ahead of its time, like most of the operating system, and made system programming on DECsystem-10s simple and powerful.