【正文】 th analysis of the data and so, despite being more efficient, the 1890 census cost about double (actually 198%) that of the 1880 census. 1892 William S. Burroughs (18571898), of St. Louis, invents a machine similar to Felt’s (see 1886) but more robust, and this is the one that really starts the mechanical office calculator industry. 1896 IBM founded (as the Tabulating Machine Company), see 1924. Founded by Herman Hollerith (18601929, see also 1890). 1899 Everything that can be invented has already been invented., Charles H. Duell, director of the . Patent Office 1906 Henry Babbage, Charles’s son, with the help of the firm of R. W. Munro, pletes the mill of his father’s Analytical Engine, just to show that it would have worked. It does. The plete machine is never produced. 1906 Electronic Tube (or Electronic Valve) developed by Lee De Forest in America. Before this it would have been impossible to make digital electronic puters. 1911 Merger of panies, including Herman Hollerith’s Tabulating Machine Company, to Computing Tabulating Recording Company which became IBM in 1924. 1919 W. H. Eccles and F. W. Jordan publish the first flipflop circuit design. 1924 February International Business Machines (IBM corporation) formed after more mergers involving the Computing Tabulating Recording Company see 1911. By 1990 IBM had an ine of around $69 Billion (and 373,816 employees), although in 1992 recession caused a cut in stock dividends (for the first time in the pany’s history) and the sacking of 40,000 employees. 19311932 E. WynnWilliams, at Cambridge, England, uses thyratron tubes to construct a binary digital counter for use in connection with physics experiments. 1935 International Business Machines introduces the IBM 601, a punch card machine with an arithmetic unit based on relays and capable of doing a multiplication in 1 second. The machine bees important both in scientific and mercial putation, and about 1500 of them are eventually made. 1937 Alan M. Turing (19121954), of Cambridge University, England, publishes a paper on putable numbers the mathematical theory of putation. This paper solves a mathematical problem, but the solution is achieved by reasoning (as a mathematical device) about the theoretical simplified puter known today as a Turing machine. 1937 Gee Stibitz () of the Bell Telephone Laboratories (Bell Labs), New York City, constructs a demonstration 1bit binary adder using relays. This is one of the first binary puters, although at this stage it was only a demonstration machine improvements continued leading to the ’plex number calculator’ of Jan. 1940. 1938 Claude E. Shannon (1916) publishes a paper on the implementation of symbolic logic using relays. 1938 Konrad Zuse (19101995) of Berlin, with some assistance from Helmut Schreyer, pletes a prototype mechanical binary programmable calculator, the first binary calculator it is based on Boolean Algebra (see 1848). Originally called the V1 but retroactively renamed Z1 after the war. It works with floating point numbers having a 7bit exponent, 16bit mantissa, and a sign bit. The memory uses sliding metal parts to store 16 such numbers, and works well。 this scheme requires fewer relays than straight BCD. Rather than requiring users to e to the machine to use it, the calculator is provided with three remote keyboards, at various places in the building, in the form of teletypes. Only one can be used at a time, and the output is automatically displayed on the same one. In September 1940, a teletype is set up at a mathematical conference in Hanover, New Hampshire, with a connection to New York, and those attending the conference can use the machine remotely. 1941 Summer Atanasoff and Berry plete a specialpurpose calculator for solving systems of simultaneous linear equations, later called the ABC (AtanasoffBerry Computer). This has 60 50bit words of memory in the form of capacitors (with refresh circuits the first regenerative memory) mounted on two revolving drums. The clock speed is 60 Hz, and an addition takes 1 second. For secondary memory it uses punch cards, moved around by the user. The holes are not actually punched in the cards, but burned. The punch card system’s error rate is never reduced beyond %, and this isn’t really good enough. (Atanasoff will leave Iowa State after the US enters the war, and this will end his work on digital puting machines.) 1941 December Now working with limited backing from the DVL (German Aero nautical Research Institute), Zuse pletes the V3 (later Z3): the first operational programmable calculator. It works with floating point numbers having a 7bit exponent, 14bit mantissa (with a 1 bit automatically prefixed unless the number is 0), and a sign bit. The memory holds 64 of these words and therefore requires over 1400 relays。 again, the program and data are read from paper tapes. An innovative feature is that, for greater reliability, numbers are represented in a biquinary format using 7 relays for each digit, of which exactly 2 should be on: 01 00001 for 0, 01 00010 for 1, and so on up to 10 10000 for 9. Some of the later machines in this series will use the biquinary notation for the digits of floatingpoint numbers.) 1943 December The earliest Programmable Electronic Computer first ran (in Britain), it contained 2400 Vacuum tubes for logic, and was called the Colossus. It was built, by Dr Thomas Flowers at The Post Office Research Laboratories in London, to crack the German Lorenz (SZ42) Cipher used by the ’Enigma’ machines. Colossus was used at Bletchly Park during WWII as a successor to April’s ’Robinson’s. It translated an amazing 5000 characters a second, and used punched tape for input. Although 10 were eventually built, unfortunately