UNIVAC 490

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The UNIVAC 490 was a 30-bit word core memory machine with 16K or 32K words; 4.8 microsecond cycle time made by UNIVAC. It was a commercial derivative of a computer Univac Federal Systems developed for the U..S. Navy. That system was the heart of the Naval Tactical Data System which pioneered the use of shipboard computers for air defense. The military version went by a variety of names: AN/USQ-20, MIL-1206 and CP642. Seymour Cray designed this system before he left UNIVAC to found Control Data Corporation.

The instruction word format:

f - Function code designator (6 bits)
j - Branch condition designator (3 bits)
k - Operand-interpretation designator (3 bits)
b - Operand address modification designator (3 bits)
y - Operand designator (15 bits)

Numbers were represented in one's complement.

The machine provided the programmer with the following registers:

Seven B-registers (Address modifying index registers) 15 bits each
One A-register or accumulator 30 bits
One Q-register and auxiliary arithmetic register 30 bits

Various customers used this machine type - principally airline reservations systems at Eastern Air Lines (1963) and British European Airways (BEACON - 1964).

The standard Operating System was REX (RealTime Exec), except at Eastern and B.E.A. where a custom operating system was developed for airline reservations (CONTORTS - CONTrol Of Real Time System). CONTORTS was the origin of Univac's subsequent RT operating systems for 494 (STARS) and later converted to the 1100 Series (RTOS).