Metrovick 950
| 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 or seven machines, which were "used commercially within the company" or "mainly for internal use". The 950 appears to have been Metrovick's first and last commercial computer offering.
In November 1953 Richard Grimsdale and Douglas Webb of Manchester University first demonstrated their prototype transistorized computer using 92 point-contact transistors and 550 diodes in order to test the suitability of transistors in improving the reliability of the Manchester Mark 1 computer. This machine was similar to the Mark I, except that it did not include Williams tubes and used only the magnetic drum for main memory. The machine was based on a 48-bit word, although 4 bits were used for timing and thus not available for program use. This machine used thermionic valves to generate a clock frequency of 125 kHz.
The only storage used was a drum (rescued from the Manchester Mark 1). This meant that the average random access time to a word in store was half a drum revolution, i.e., with 64 words on a track, 32 times the random access time for a word if it could be stored in a true RAM. So the Transistor Computer was slower than the Mark 1. Both versions had a pseudo 2-address (or 1+1) instruction format, where the address of the next instruction to be obeyed was contained within each instruction, to facilitate "optimum programming". The drum was even used to store the Accumulator and the Current Instruction.
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