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Ferranti Mark 1,
the world's first commercially available general-purpose electronic computer, produced by Ferranti [1]. The first machine was delivered to the University of Manchester in February 1951 [2]. Ferranti Mark 1 was a tidied up and commercialized version of the Manchester Mark 1 developed in 1948-1949 at the University of Manchester, which was a further development of the Manchester Small-Scale Experimental Machine (SSEM, nicked Baby) by Frederic C. Williams, Tom Kilburn and Geoff Tootill [3]. During the 1940s, Alan Turing and others such as Konrad Zuse developed the idea of using the computer's own memory to hold both the program and data. It was John von Neumann who became widely credited with defining that stored-program computer architecture, on which the Mark 1 was based [4] [5].
Ferranti Mark 1 Console [6]


The Mark 1 used a 20-bit word stored as a single line of dots on a Williams-Kilburn tube, each tube storing 64 lines. Instructions were stored in a single word, while numbers were stored in two words (40 bits). The main memory had eight tubes, each storing one 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, used to modify instructions. An extra 20-bit word per tube stored an offset value into the secondary storage, a 512-page magnetic drum.

Williams-Kilburn tube [7]


The 20 bit instructions had an address and an operator part. The coding of instructions was: bits 0-8 the CRT address, bits 10-12 the B-line address and bits 13-19 the function code. Writing of programs was based on a numerical system to the base 32 [8]. Integer numbers were usually treated as 40 bit double words, negative numbers already represented as Two's complement. The Mark 1 had an instruction to find the position of the most significant digit [9] aka Bitscan reverse or Leading Zero Count for the purpose to convert integers to normalized floating point numbers, as well as a Population Count instruction for Cryptography purposes [10]. Arithmetical and logical instructions other than multiplication took 1.2 milliseconds (5 x 240 microseconds beats ), 40*40=80 bit multiplication 2.16 milliseconds (9 beats) [11] [12].


The first successful AI program was written in 1950/1951 by Christopher Strachey, initially for the Pilot ACE at National Physical Laboratory, exhaustings its memory [13]. Strachey’s checkers (draughts) program was soon ported and ran on the Mark I computer at the University of Manchester, and by the summer of 1952 the program could play a complete game of checkers at a reasonable speed [14] [15], and already featured Bitboards for White, Black and Kings to represent the board [16].


Alan Turing, while affiliated with the University of Manchester began "porting" his pen and paper program Turochamp to run on a Mark 1, as well started with Michie's and Wylie's program Machiavelli, but could not complete them [17]. Influenced by Turing's ideas, Dietrich Prinz developed the first limited chess program for the Ferranti Mark 1 in 1951, dubbed Mate-in-two [18] [19].


by Jack Good, 1998 [20]:
In a letter to F C Williams in July 1951 I said "A facetious question is whether it is intended to display chess positions on the monitoring tubes". Of course today it is no longer at all facetious.

See also

Selected Publications


External Links


  1. ^ Ferranti: the Company from Atlas Computer Laboratory
  2. ^ Ferranti Mark 1 - History and specifications, from Wikipedia
  3. ^ Manchester Small-Scale Experimental Machine from Wikipedia
  4. ^ Manchester Mark 1 - Background
  5. ^ Von Neumann architecture from Wikipedia
  6. ^ The Ferranti Mark 1 from Mark 1 Photo Gallery, The two larger CRT displays could be switched to show the current contents of any of the 8 pages. The four smaller displays (presumably) permanently showed the current contents of the four auxiliary tubes, A (80-bit Accumulator), B (8 20-bit B-lines), C (Control Address and Present Instruction) and D (current multiplicand value). Copyright The University of Manchester 1998, 1999
  7. ^ Williams tube from Wikipedia
  8. ^ Programming the Mark 1
  9. ^ Alan Turing (1949). Alan Turing's Manual for the Ferranti Mk. I. transcribed in 2000 by Robert Thau, pdf from The Computer History Museum, 9.4 The position of the most significant digit
  10. ^ Cryptography is also a significant application of the /R function symbol, which counts the number of one bits in a word; Turing refers to this as the "sideways adder" in his quick-reference summary. from Alan Turing (1949). Alan Turing's Manual for the Ferranti Mk. I. transcribed in 2000 by Robert Thau, pdf from The Computer History Museum, 9.4 The position of the most significant digit
  11. ^ Ferranti Mark 1 - Specification from Computer 50 - The University of Manchester Celebrates the Birth of the Modern Computer
  12. ^ 11. The time occupied by various operations from Alan Turing (1951). Programmers' Handbook for the Manchester Electronic Computer Mark II. 1st edition
  13. ^ Christopher Strachey from Wikipedia
  14. ^ artificial intelligence (AI) :: Early milestones in AI from Britannica Online Encyclopedia
  15. ^ The “Modern” History of Artificial Intelligence and Programs from Neuroscience Of Intelligence
  16. ^ On Bitboards for White, Black and Kings to represent the checkers board, see David Link Video at 1:04:02
  17. ^ Chronology of Computing compiled by David Singmaster
  18. ^ Dietrich Prinz (1952). Robot Chess. Research, Vol. 6, reprinted 1988 in Computer Chess Compendium
  19. ^ First video game - 1947–1958: Chess, from Wikipedia
  20. ^ Excerpts from Acceptance Speech for the 1998 Computer Pioneers Award from the IEEE - Jack Good hosted by Atlas Computer Laboratory
  21. ^ Mark 1 Documents from Computer 50 - The University of Manchester Celebrates the Birth of the Modern Computer
  22. ^ Papers of Dr Dietrich G. Prinz - ELGAR: Electronic Gateway to Archives at Rylands The John Rylands University Library The University of Manchester
  23. ^ UK National Archive for the History of Computing - Draft Catalogue Version 1.0, August 15, 2005 (pdf)

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