In the 1940s, 1950s, 1960s, and early 1970s, computers were room-sized or refrigerator-sized monsters that cost a fortune (as in "as much as your house and every other house on the whole street combined"). They were not very powerful or plentiful, so their time was precious. They were also the mainstay of the world of big business; before IBM loaned an air of business legitimacy to the microcomputer with the introduction of the IBM Personal Computer, and even for another decade afterward, almost all business computing was done on IBM 360 and 370 mainframes. Even today, mainframes can be still be found clanking away in corporations and government agencies, handling everything from payroll to transaction processing. During this period, the transistor and integrated circuit were invented, paving the way for further miniaturisation and increased processing power.
Of particular interest to gamers is Digital Equipment Corporation's Programmed Data Processor family of minicomputers. The PDPs were the first computers designed with cost as a consideration. This made them more plentiful and less critical than mainframes. The PDP-1, PDP-7, and PDP-8 (1960-65) had computing horsepower similar to the Apple ][ or the original IBM Personal Computer. The PDP-11 (1970) was closer to a 286 PC/AT or the original Apple Macintosh. The PDP-6 and PDP-10 (1963-66) were much larger and considered mainframes. All models supported video output, so they were powerful enough to play games and cheap enough for universities to buy two or three and let their students do what they wanted with them. The Playful Hacker culture starts here, as do video games.
Another important source of early videogaming was the PLATO network, which began in the early 1960s and peaked in the 1970s. What started as a digital learning assistant ended up as a prototype of the world-wide web with email, message boards, chat rooms, and multiplayer online games. Multi User Dungeons and online shooters start here.
In the 1980s, mainframes and minis began to be replaced by rack-mounted services accessed by personal computers over the network, but mainframes haven't gone away, due to their redundant, fault-tolerant designs. Many cash registers and ATMs are effectively front ends to a mainframe somewhere.
As you'd expect, Ur Examples abound.
- Cathode Ray Tube Amusement Device (1947)
- Daughts (1952, unique mainframe)
- OXO (1952, unique mainframe)
- Nim (1952, unique mainframe)
- Tennis for Two (1958, military-derived custom hardware)
- Spacewar! (1962, PDP-1)
- The Sumer Game (1968, PDP-8), later ported from FOCAL to BASIC in 1974 as Hamurabi
- Lunar Lander (1969, PDP-8)
- Space Travel (1969, Multics system; Unix was invented so it could be ported to a PDP-7)
- The Oregon Trail (1971, mainframe)
- Star Trek Text Game (1971, SDS Sigma 7 mainframe)
- Hunt the Wumpus (1972, University of Massachusetts mainframes)
- Empire (1973, PLATO network)
- Maze War (1973, Imlac PDS-1 graphics minicomputer)
- Spasim (1974, PLATO network)
- Colossal Cave (1975, PDP-10)
- dnd (1975, PLATO network)
- Dungeon (1975, PDP-10)
- Moria (1975, PLATO network)
- Panther (1975, PLATO network)
- Avatar (1978, PLATO network)
- Multi-User Dungeon (1978, PDP-10)
- Zork (1979, PDP-10)
- Rogue (1980, Unix system)
- Tetris (1985, Elektronika60)
- DoomsDay 2000 (1987, VAX/VMS)
Appearances of these computers in media:
- Connections: This 1978 documentary series prominently showed several minicomputers in their earliest age, with some surprisingly (but not completely) accurate predictions about how the advent of the computer—specifically, the ability to easily access and analyse immense amounts of information—would affect society over the following quarter-century.
- Mad Men: A major development in Season 6 (1967-68) involves Harry Crane's efforts to get SCDP to install an IBM mainframe to track media and accounts. Eventually, Harry gets his way thanks to Jim Cutler—who installs it in the Creative lounge.