OS/4 is a discontinued operating system, introduced in 1972, from UNIVAC for their 9400, 9480, and 9700 computer systems. It is an enhanced version of UNIVAC's 9400 Disc Operating System. OS/4 is a disc-resident system requiring 64 KB of main memory, two disc drives, a punched-card reader and a printer. The resident memory footprint is approximately 24 KB.
UNIVAC intended to replace OS/4 with a new system known as OS/7; however, OS/7 development was discontinued in 1975 when the 9700 was made part of the new UNIVAC Series 90 line as the 90/70.
References
"UNIVAC 9700" (PDF). Bitsavers. Datapro. Retrieved April 7, 2023. http://bitsavers.org/pdf/univac/9x00/datapro/70C-877-03_7201_UNIVAC_9700.pdf ↩
"UNIVAC 90/60,90/70, and 90/80" (PDF). Datapro. September 1976. Retrieved Aug 24, 2018. http://bitsavers.informatik.uni-stuttgart.de/pdf/univac/series_90/datapro/70C-877-06_7609_UNIVAC_90-60_70_80.pdf ↩
"Univac 9000, Series 70 Sites Promised Help Moving to VS/9". Computerworld. November 26, 1975. Retrieved Aug 24, 2018. https://books.google.com/books?id=nMHHJQxdDHYC&pg=PA11 ↩