1) 1890 Hollerith Tabulation System. Mechanical machine to sort US census data. Hollerith's Tabulating Machine Company, TMC, was later to merge with Computing-Tabulating-Recording Co, later to become IBM (1914) 2) 1937-41 Z1 and Z3 built by Konrad Zuse and Helmut Schreyer Z1 first binary machine. Z3 first floating point machine (used 2600 relays). Speed was 5Hz ! 3) 1937 Automatic Sequence Controlled Calculator (ASCC) or Harvard Mk I Part vacuum tube - part relay. Hard wired coding. Code written by Grace Hopper. According to Ms Hopper - moths would fly in through the open windows at night and get stuck in the relays. This would render the machine unless and it would have to be "de-bugged". 4) 1940 ? Enigma - Electromechanical state machine. Colossus wouldn't have been built without it. 5) 1943 Colossus - Vacuum tube code craker. Not a general purpose machine, built solely to solve Enigma ciphers. Hard wired coding and paper tape. 1500 valves. 6) 1944 ENIAC - First general purpose machine. Hard wired and paper tape program, worked in decimal. Program storage added after development of Manchester Mk I and EDSAC. 7) 1946 Manchester Mark I - First stored program computer. The Williams tube (CRT) was used for program storage. Commercial version was the Ferranti Mk I Followed by EDSAC in 1949. 8) 1951 UNIVAC - first successful commercial computer. One of the first machines to use compiled software, another of Grace Hopper's ideas. 9) 1951 LEO I (Lyons Electronic Office) J. Lyons & Company Ltd First British mainframe. Lyons bought by English Electric Company later to become ICL and the end of the British computer industry. 10) 1956 MIT Lincoln Labs TX-0 - First solid state computer 11) 1964 CDC's 6600 - Seymour Cray's first super computer, 3 MIPS 12) 1965 DEC PDP8 - The first true minicomputer 13) 1968/9 The Apollo guidance computer - Helped get man to the moon. 14) 1971 Intel 4004 - First commercially available microprocessor 15) 1972 HP 35 - Perhaps the first scientific pocket calculator ? (On the list 'cos I like HP stuff) 16) 1974 Xerox Alto - The mouse makes it's first appearence as well as windows, menus and icons. Ground breaking stuff. 17) 1975 MITS Altair 8800. First popular personal computer . 8080 based, 256 bytes of memory, no keyboard or display. Paul Allen and Bill Gates wrote a BASIC interpreter for it and the Altairs bus structure evolved into the S-100 bus. 18) 1976/7 Steve Jobs and Steve Wozniak produced the Apple I followed by Apple II. First popular 6502 personal computer. Atari and Commodore followed. 19) 1976 CRAY 1 - First real supercomputer ? 166 MIPS 20) 1978 DEC VAX11/780 - 4Gbyte virtual memory ! 21) 1981 The IBM PC - A veil of darkness falls Honourable mention Arcade games ought to get a mention, they created an entire industry. Atari for Asteroids, Midway for space invaders. Chris Leyson