Manufacturing AN/UYK-20 Minicomputers at Sperry Univac in 1975

The AN/UYK-20 minicomputer was designed by Sperry Univac’s Federal Systems Division for the U.S. Navy which, in 1972, mandated its use for small- and medium-sized shipboard and shore systems, replacing the plethora of incompatible minicomputers which were then in use. The “Yuck Twenty”, as programmers and engineers called it, was built into a cube-shaped metal box ruggedised against the shipboard environment and designed to be able to fit through a 25 inch (63.5 cm) diameter hatch.


The AN/UYK-20 used a 16-bit word length and nonvolatile magnetic core memory. Logic was mostly implemented with small-scale integrated circuits in dual inline packages on circuit boards with a conformal coating to protect against corrosion from sea air.

The first AN/UYK-20s were delivered to the Navy in 1974. Amazingly, almost half a century later, some remain in service today (2023), although many were replaced by the upward compatible AN/UYK-44, introduced in 1984. A total of 2,804 of these machines were built.

This film shows volume production of Yuck Twenties at a Sperry plant in Clearwater, Florida (before that city became better known for another for-profit enterprise).