The UNIVAC 490 was a 30-bit word core memory machine with 16K or 32K words; 4.8 microsecond cycle time made by Univac.

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 Airlines (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).

External link

• UNIVAC 490 Real-Time System (http://ed-thelen.org/comp-hist/BRL61-u.html#UNIVAC-490)