Ferranti Mark 1 delivered to Manchester University
The Ferranti Mark 1, also known as the Manchester Electronic Computer in its sales literature, and thus sometimes called the Manchester Ferranti, was the world's first commercially available general-purpose electronic computer.
The first machine was delivered to Manchester University in February 1951, just ahead of the UNIVAC I which was delivered to the United States Census Bureau a month later.
The machine was built by Ferranti of the United Kingdom. It was based on the Manchester Mark 1, which was designed at the University of Manchester by Freddie Williams and Tom Kilburn. The Manchester Mark 1 effectively served as a prototype for the Ferranti Mark 1; the main improvements over it were in the size of the primary storage and secondary storage, a faster multiplier, and additional instructions.
The Mark 1 used a 20-bit word stored as a single line of dots on a Williams tube display, each tube storing a total of 64 "lines" of dots. Instructions were stored in a single word, while numbers were stored in two words. The main memory consisted of eight tubes, each storing one such "page" of 64 words. Other tubes stored the single 80-bit accumulator (A), the 40-bit "multiplicand/quotient register" (MQ) and eight "B-lines", or index registers, which was one of the unique features of the Mark 1 design. The accumulator could also be addressed as two 40-bit words. An extra 20-bit word per tube stored an offset value into the secondary storage. Secondary storage was provided in the form of a 512-page magnetic drum, storing two pages per track, with about 30 milliseconds revolution time. The drum provided eight times the storage of the original designed at Manchester.
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