J. Lyons accounting office 1900

Analytical Calculation  Reduce a problem to a 2 nd and then a 3 rd  Application of rules and procedures  Problem is solved by the machine itself

Analytical Calculator  Governed by a flexible programming system  Equipped with a modifiable control unit  no human intervention

Joseph Henry Electromagnetic relay

The electronic revolution Edison effect (1883) electric current passes from hot to cold electrode in a vacuum electrons are expelled from the hot wire Edison effect (1883) electric current passes from hot to cold electrode in a vacuum electrons are expelled from the hot wire Thomas A. Edison

Fleming’s valve Positively charged metal plate in the tube. Positively charged metal plate in the tube. Free electrons expelled by the heated filament all precipitate onto the plate generating electric current Free electrons expelled by the heated filament all precipitate onto the plate generating electric current diode1904 diode 1904

Triode  inserted a third electrode into the tube, between the plate and the filament  Amplified the incoming current 1907

Flip-flop device – dual triode  Bistable electronic device  Incoming current flips both triodes into an opposite state

Electro-mechanical calculation Based on electro-magnetic relays  Zuse  Stibitz  Aiken

George Stibitz Bell Laboratories  Model K literally built in his kitchen – 1937  a binary half-adder from phone relays, possiblythe first binary calculator  a binary half-adder from phone relays, possibly the first binary calculator  Remote job entry  Floating point arithmetic

Zuse: German Pioneer Patent applied for 1936

Claude Shannon  described the similarity between symbolic logic and switching circuits  described the similarity between symbolic logic and switching circuits  In 1936, he coined the term “bit” from binary digit, the smallest particle of computer information

Harvard - IBM Mark 1 US navy ballistics  Completed in 1941  16 m long, 2.6 m high, 0.6 m deep  5 tons  850 km of wire  1.75 x 10 5 connections Howard Aiken  Although inspired by Babbage, it had no conditional branching

Automatic Sequence Controlled Calculator Harvard Mark I

John Vincent Atanasoff first general-purpose electronic digital computer J. Atanasoff and C. Berry

The ABC Machine problems involving systems of simultaneous linear equations The ABC Machine problems involving systems of simultaneous linear equations never finished !  Binary digits to represent all numbers and data  Performed all calculations using electronics rather than wheels, ratchets, or mechanical switches  computation and memory separated

The ABC Machine  320 kg  1.6 km of wire  280 dual-triode vacuum tubes  31 thyratrons  about the size of a desk.

Colossus designed by Thomas Harold Flowers Alan Turing M.H.A. Newman  assisted the code- breaking efforts at Bletchley Park  first digital (partially) programmable, electronic computer  Completed in

Bletchley Park British decoded 75,000 of the 80,000 messages they intercepted World War II

 Capable of performing binary logic calculation  Capable of conditional branching  Capable of automatically printing  Capable of storing program already written for the purpose of executing pre-selected functions Colossus

E lectrical N umerical I ntegrator and C alculator  ballistic tables  weather prediction  atomic-energy calculations  cosmic-ray studies  thermal ignition  random-number studies  wind-tunnel design Eniac

ENIAC another monster machine  72 m2  U-shape 6 m wide by 12 m long  18,000 vacuum tubes  200 kilowatts of power in operation  10,000 condensers  6,000 switches  1,500 relays

None of these machines was a true computer  All closely resembled Babbage’s Analytical engine  Program executed independently of results  Process could not change in function of the results

Alan Mathison Turing « a machine which can be made to do the work of any special-purpose machine, …to carry out any piece of computing, if a tape bearing suitable "instructions" is inserted into it »

War hero, athlete, mathematician, computer scientist I believe that, at the end of the century, the use of words and general educated opinion will have altered so much that one will be able to speak of machines thinking without expecting to be contradicted. A. Turing I believe that, at the end of the century, the use of words and general educated opinion will have altered so much that one will be able to speak of machines thinking without expecting to be contradicted. A. Turing

The Turning Test