The Virtues of Sharing

Big companies could afford big mainframes. But what about users with aspirations bigger than their budgets?

Users who can’t individually buy a mainframe can share one. Because most tasks are small, and computers work faster than users can respond, the machine can juggle many jobs—giving users the illusion of having the computer’s undivided attention and providing seemingly real-time access.

The Origin of Timesharing

MIT unveiled its Compatible Time-Sharing System (CTSS) in 1961. Initiated by AI pioneer John McCarthy, it operated until 1973 and may have been the first timesharing system available to a large community. It also laid the groundwork for MIT’s Project MAC.

Launched in 1963 with Defense Department support, Project MAC envisioned timesharing available to anyone, anywhere—like telephone or electrical utilities. Project MAC later joined with GE and Bell Labs to develop a prototype commercial timesharing utility called Multics.

By 1985, about 80 Multics systems operated. Several remained in use until 2000. Video (Animation): Animation excerpt from vintage video explaining timesharing concept.

Basic Timesharing

“Be easy for beginners to use.” That was the first of eight design principles behind the Dartmouth Time-Sharing System (DTSS) unveiled in 1963.

Created for both savvy users and non-techies, DTSS used the BASIC programming language, which later was widely available on varied computers, from “game-playing” microcomputers to mainframes.