UNIVAC 490
| Company type | Computer system |
|---|---|
| Industry | Computer hardware |
| Predecessor | AN/USQ-17 |
| Founder | Seymour Cray (designer) |
| Headquarters | United States |
| Products | UNIVAC 490 computer system |
The UNIVAC 490 was a UNIVAC computer system equipped with either 16K or 32K words of magnetic-core memory, utilizing 30-bit word length and operating with a 4.8 microsecond cycle time. This machine represented a commercial version of the instruction set originally created for the AN/USQ-17 by Seymour Cray while working for the United States Navy. Notably, this design was Cray's final project before his departure from UNIVAC to join Control Data Corporation.
Building upon this foundation, Univac Federal Systems developed the design into the AN/USQ-20, which became integral to the US Navy's Naval Tactical Data System, a pioneering effort in shipboard computing dedicated to air defense. The military variant was identified by several designations: UNIVAC 1232, AN/USQ-20, MIL-1206, and CP642.
Overview
Production totaled at least 47 units, with serial numbers ranging from 101 to 147. Among these, six were deployed at NASA, where they played vital roles in the Gemini and Apollo missions by managing data display consoles within Houston Mission Control. Both the USAF and Lockheed operated two units each.
In the commercial sector, the 490 Real-Time system was instrumental in airline reservation platforms for Eastern in 1963 and for BEA through the BEACON system in 1964. Additional commercial installations included two units at Westinghouse, two at Hammermill Paper Company, and single units at Alcoa, U.S. Steel, Bethlehem Steel, and General Motors.
Today, the only nearly intact civilian UNIVAC 490 system is exhibited at the System Source Computer Museum located in Hunt Valley, Maryland, accompanied by a comprehensive archive of original documentation.
The primary operating system used was REX (RealTime Exec), except for Eastern and BEA where a specialized OS named CONTORTS (CONTrol Of Real Time System) was developed specifically for airline reservation applications. CONTORTS subsequently influenced Univac's later real-time operating systems such as STARS for the 494 and ultimately the RTOS employed in the 1100 Series.
Architecture
The instruction word was structured as follows:
- f – Function code (6 bits)
- j – Branch condition code (3 bits)
- k – Operand interpretation code (3 bits)
- b – Operand address modification code (3 bits)
- y – Operand address or designator (15 bits)
All numeric data utilized ones' complement representation.
Available registers included:
- Seven B-registers serving as address-modifying index registers, each 15 bits wide
- One A-register functioning as the accumulator with 30-bit width
- One Q-register acting as an auxiliary arithmetic register, also 30 bits
Hardware
The arithmetic logic unit incorporated a total of 13,819 transistors alongside 37,543 diodes of various types.
Successor systems
In June 1965, UNIVAC launched the UNIVAC 490 Modular Real Time Systems lineup, which consisted of models UNIVAC 491, 492, and 494. The UNIVAC 494 gained notable recognition due to its extensive deployment by NASA within the Apollo Mission communications infrastructure. Other significant operators included BEA, Iberia Airlines, Scandinavian Airlines, and Lufthansa.
As UNIVAC transitioned its emphasis toward the UNIVAC 1100/2200 series, an emulator was engineered through microcode to enable the 1110/80 system to operate in a mode compatible with the 494.