AN/USQ-20
The AN/USQ-20, or CP-642 or Naval Tactical Data System (NTDS), was designed as a more reliable replacement for the Seymour Cray-designed AN/USQ-17 with the same instruction set. The first batch of 17 computers were delivered to the Navy starting in early 1961.
A version of the AN/USQ-20 for use by the other military services and NASA was designated the UNIVAC 1206. Another version, designated the G-40, replaced the vacuum tube UNIVAC 1104 in the BOMARC Missile Program.
In accordance with the Joint Electronics Type Designation System (JETDS), the "AN/USQ-20" designation represents the 20th design of an Army-Navy electronic device for general utility special combination equipment. The JETDS system also now is used to name all Department of Defense electronic systems.