Varian Data Machines
The 620i and 620/L series were parallel, binary 16-bit general-purpose digital computers with core memory expandable to 32,768 words. An 18-bit word length (for data, not addresses) was optionally available. A basic machine cycle took 1.8 microseconds, and the core memory read time was 700 nanoseconds. The computers uses two's complement arithmetic and had four main registers - accumulator A, accumulator extension B, an index register X and a program counter register. Addressing modes were direct, immediate and indexed. The instruction set had more than one hundred arithmetic, logic and control instructions and some variants supported microprogramming. These models used a hardware front panel console that allowed starting and stopping the machine, examining memory and registers and changing memory or registers with front-panel switches. The processor was made with integrated circuit transistor transistor logic from the 7400 series. The system was packaged in a 19 inch rack and used 340 watts of power at 120 V AC. The 620/F was a variation with a faster machine cycle time of 750 nanoseconds. The 620/L-100 was released in 1973. It had a cycle time of 950 nanoseconds and a more compact system chassis than the 620/F. The Sperry V70 series had semiconductor memory but could also support core. Various models were released between 1972 and 1977.
Varian V72 computer systems were installed at Bruce Nuclear Generating Station as the digital control computer system which monitors and controls the major reactor and power plant functions. As of February 2017 these were still in operation, and planned to be replaced by more modern systems in 2018 and 2019.
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- Computer History Museum, Selling the Computer Revolution - Marketing Brochures in the Collection: Varian Data Machines
- http://www.bitsavers.org/pdf/varian/98A9902504_Varian_620_Training_Manual_Jan73.pdf Varian 620 Manual retrieved 2012 July 24
- http://www.dimka.com/daily/external-pages/spies.com-~aek-orphanage.html Minicomputer Orphanage, retrieved 2012 July 24
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