AN/USQ-20

The AN/USQ-20, or Naval Tactical Data System (NTDS), was designed as a more reliable replacement for the 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.

The machine was the size and shape of an old-fashioned double-door refrigerator, about six feet tall (roughly 1.80 meters).

instructions were represented as 30-bit words in the following format: f 6 bits function code j 3 bits jump condition designator k 3 bits partial word designator b 3 bits which index register to use y 15 bits operand address in memory

Numbers were represented as 30-bit words. This allowed for five 6-bit alphanumeric characters per word.

The main memory was 32,768 words of core memory.

The available processor registers were:
*one 30-bit arithmetic (A) register.
*a contiguous 30-bit Q register (total of 60 bits for the result of multiplication or the dividend in division).
*seven 15-bit index (B) registers.

ee also

*List of UNIVAC products
*History of computing hardware

External links

* [http://ed-thelen.org/comp-hist/univac-ntds.html UNIVAC-NTDS: UNIVAC 1206, AN/USQ-20] – From the Antique Computer website