Real-Time Multiprogramming Operating System

Real-Time Multiprogramming Operating System (RTMOS) was a 24-bit process control operating system developed in the 1960s by General Electric{{cite book|url=https://archive.org/details/bitsavers_gePAC4000P0PgmgManOct67_6687740/mode/1up|title=GE-PAC 4020 Programming Manual|page=5|year=1967|publisher=General Electric|accessdate=2013-09-27}} that supported both real-time computing and multiprogramming.{{cite journal|last=Spang|first=H. A. III|title=The structure and comparison of three real-time operating systems for process control|journal=Automatica|date=January 1972|volume=8|issue=1|pages=49–64|doi=10.1016/0005-1098(72)90009-X|url=http://dl.acm.org/citation.cfm?id=2244947|accessdate=23 August 2013|url-access=subscription}}{{cite conference|last=Spang|first=H. A. III|title=Measurement and Improvement of Memory Allocation in a Process Computer|conference=4th IFAC/IFIP International Conference on Digital Computer Applications to Process Control|year=1974|volume=93|pages=236–247|doi=10.1007/978-3-642-65796-2_20}} Programming was done in assembly language or Process FORTRAN. The two languages could be used in the same program, allowing programmers to alternate between the two as desired.

Multiprogramming operating systems are now considered obsolete, having been replaced by multitasking.{{citation needed|date=December 2015}}