Metrovick 950
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| Manufacturer | Metropolitan-Vickers |
|---|---|
| Release date | 1956 |
The Metrovick 950 was a transistorized computer, built from 1956 onwards by British company Metropolitan-Vickers, to the extent of six[1] or seven machines,[2] which were "used commercially within the company"[2] or "mainly for internal use".[1] The 950 appears to have been Metrovick's first and last commercial computer offering.
Transistor Computer
Prototype
In November 1953
The only storage used was a
Improved version
By 1955 the design was re-built with a Mark I-style B-line accumulator/index register and hardware multiplier. The added circuitry brought the machine to a total of 250 transistors. It used only 150 watts of power, an astonishingly low figure in an era when machines typically used tens of kilowatts to warm their valves. The new model could add two 44-bit numbers in 1.5 drum revolutions, which, at a drum spin rate of 3000 RPM, amounted to roughly 30 milliseconds per addition. Although faster than the Mark I internally, the lack of Williams tubes made it run much more slowly; the Mark I could add two 40-bit numbers in 1.8 milliseconds.
The prototype computer (November 1953) had a simple seven-function order code and one track of 64 words for main storage. For the full-size computer (April 1955) the order code and storage were much extended and a hardware multiplier included. A third "regenerative" drum track formed an 8-word B store. Arithmetic was serial, with a pulse rate of 125,000 per second. The instruction times were directly related to the 30-millisecond drum revolution time (the basic unit being the time to read a word, i.e. 1/64th of a revolution).
The expanded 1955 machine had a total of 200 point-contact transistors and 1300 point diodes,[1] which resulted in a power consumption of 150 watts. There were considerable reliability problems with the early batches of transistors and the average error free run in 1955 was only 1.5 hours.
Metrovick 950
They changed all the circuits to more reliable types of junction transistors,[1] although it appears they may have built one example with the earlier designs. The production version was known as the Metrovick 950 and was built from 1956 to the extent of six[1] or seven machines,[2] which were "used commercially within the company"[2] or "mainly for internal use".[1]