System 4 or System IV may refer to:
*
Acorn System 4
The Acorn Eurocard systems were a series of modular microcomputer systems based on rack-mounted Eurocards developed by Acorn Computers from 1979 to 1982, aimed primarily at industrial and laboratory use, but also home enthusiasts.
The experience ...
, the early minicomputer
* The fourth release of
Classic Mac OS
Mac OS (originally System Software; retronym: Classic Mac OS) is the series of operating systems developed for the Macintosh family of personal computers by Apple Computer from 1984 to 2001, starting with System 1 and ending with Mac OS 9. The ...
*
International Computers Limited#English Electric LEO Marconi (EELM), also known as ICL System 4
* Not-released Unix system between
UNIX System III and
UNIX System V
Unix System V (pronounced: "System Five") is one of the first commercial versions of the Unix operating system. It was originally developed by AT&T and first released in 1983. Four major versions of System V were released, numbered 1, 2, 3, an ...
*
STS-4 (Space Transportation System-4), the Space Shuttle mission
See also
*
IBM System/4 Pi
The IBM System/4 Pi is a family of avionics computers used, in various versions, on the F-15 Eagle fighter, E-3 Sentry AWACS, Harpoon Missile, NASA's Skylab, MOL, and the Space Shuttle, as well as other aircraft. Development began in 1965, de ...
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