Metrovick 950
Encyclopedia
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.
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 tube
s 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.
/index register
and hardware multiplier. The added circuitry brought the machine to a total of 250 transistors. It used only 150 watt
s 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 millisecond
s 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 (Nov. 1953) had a simple 7 function order code and one track of 64 words for main storage. For the full-size computer (Apr 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, 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.
became interested in the design after the success the university had selling computing time on the Mark I to commercial customers. They adopted the design of the 1955 Manchester University transistor computer as the Metrovick 950. The only relevant experience in Metropolitan-Vickers
was that in the early 1930s they had manufactured a mechanical calculating machine in the form of the differential analyser
in conjunction with Douglas Hartree
of Manchester University.
They changed all the circuits to more reliable types of junction transistor
s, 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 or seven machines, which were "used commercially within the company" or "mainly for internal use".
Transistor computer
A transistor computer is a computer which uses discrete transistors instead of vacuum tubes. The "first generation" of electronic computers used vacuum tubes, which generated large amounts of heat, were bulky, and were unreliable. A "second generation" of computers, through the late 1950s and...
, built from 1956 onwards by British
United Kingdom
The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...
company Metropolitan-Vickers
Metropolitan-Vickers
Metropolitan-Vickers, Metrovick, or Metrovicks, was a British heavy electrical engineering company of the early-to-mid 20th century formerly known as British Westinghouse. Highly diversified, they were particularly well known for their industrial electrical equipment such as generators, steam...
, 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.
Prototype
In November 1953 Richard GrimsdaleRichard Grimsdale
Richard Lawrence Grimsdale was a British electrical engineer and computer pioneer who helped to design the world's first transistorised computer.-Early life:...
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
Manchester Mark 1
The Manchester Mark 1 was one of the earliest stored-program computers, developed at the Victoria University of Manchester from the Small-Scale Experimental Machine or "Baby" . It was also called the Manchester Automatic Digital Machine, or MADM...
computer. This machine was similar to the Mark I, except that it did not include Williams tube
Williams tube
The Williams tube or the Williams-Kilburn tube , developed in about 1946 or 1947, was a cathode ray tube used to electronically store binary data....
s 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
Drum memory
Drum memory is a magnetic data storage device and was an early form of computer memory widely used in the 1950s and into the 1960s, invented by Gustav Tauschek in 1932 in Austria....
(rescued from the Manchester Mark 1
Manchester Mark 1
The Manchester Mark 1 was one of the earliest stored-program computers, developed at the Victoria University of Manchester from the Small-Scale Experimental Machine or "Baby" . It was also called the Manchester Automatic Digital Machine, or MADM...
). This meant that the average random access
Random access
In computer science, random access is the ability to access an element at an arbitrary position in a sequence in equal time, independent of sequence size. The position is arbitrary in the sense that it is unpredictable, thus the use of the term "random" in "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
Ram
-Animals:*Ram, an uncastrated male sheep*Ram cichlid, a species of freshwater fish endemic to Colombia and Venezuela-Military:*Battering ram*Ramming, a military tactic in which one vehicle runs into another...
. 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
Accumulator (computing)
In a computer's central processing unit , an accumulator is a register in which intermediate arithmetic and logic results are stored. Without a register like an accumulator, it would be necessary to write the result of each calculation to main memory, perhaps only to be read right back again for...
and the Current Instruction.
Improved version
By 1955 the design was re-built with a Mark I-style B-line accumulatorAccumulator (computing)
In a computer's central processing unit , an accumulator is a register in which intermediate arithmetic and logic results are stored. Without a register like an accumulator, it would be necessary to write the result of each calculation to main memory, perhaps only to be read right back again for...
/index register
Index register
An index registerCommonly known as a B-line in early British computers. in a computer's CPU is a processor register used for modifying operand addresses during the run of a program, typically for doing vector/array operations...
and hardware multiplier. The added circuitry brought the machine to a total of 250 transistors. It used only 150 watt
Watt
The watt is a derived unit of power in the International System of Units , named after the Scottish engineer James Watt . The unit, defined as one joule per second, measures the rate of energy conversion.-Definition:...
s 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
Revolutions per minute
Revolutions per minute is a measure of the frequency of a rotation. It annotates the number of full rotations completed in one minute around a fixed axis...
, amounted to roughly 30 millisecond
Millisecond
A millisecond is a thousandth of a second.10 milliseconds are called a centisecond....
s 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 (Nov. 1953) had a simple 7 function order code and one track of 64 words for main storage. For the full-size computer (Apr 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, 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
Metropolitan-VickersMetropolitan-Vickers
Metropolitan-Vickers, Metrovick, or Metrovicks, was a British heavy electrical engineering company of the early-to-mid 20th century formerly known as British Westinghouse. Highly diversified, they were particularly well known for their industrial electrical equipment such as generators, steam...
became interested in the design after the success the university had selling computing time on the Mark I to commercial customers. They adopted the design of the 1955 Manchester University transistor computer as the Metrovick 950. The only relevant experience in Metropolitan-Vickers
Metropolitan-Vickers
Metropolitan-Vickers, Metrovick, or Metrovicks, was a British heavy electrical engineering company of the early-to-mid 20th century formerly known as British Westinghouse. Highly diversified, they were particularly well known for their industrial electrical equipment such as generators, steam...
was that in the early 1930s they had manufactured a mechanical calculating machine in the form of the differential analyser
Differential analyser
The differential analyser is a mechanical analogue computer designed to solve differential equations by integration, using wheel-and-disc mechanisms to perform the integration...
in conjunction with Douglas Hartree
Douglas Hartree
Douglas Rayner Hartree PhD, FRS was an English mathematician and physicist most famous for the development of numerical analysis and its application to the Hartree-Fock equations of atomic physics and the construction of the meccano differential analyser.-Early life:Douglas Hartree was born in...
of Manchester University.
They changed all the circuits to more reliable types of junction transistor
Bipolar junction transistor
|- align = "center"| || PNP|- align = "center"| || NPNA bipolar transistor is a three-terminal electronic device constructed of doped semiconductor material and may be used in amplifying or switching applications. Bipolar transistors are so named because their operation involves both electrons...
s, 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 or seven machines, which were "used commercially within the company" or "mainly for internal use".