Analytical Calculation by malj


									J. Lyons accounting office 1900

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


Analytical Calculator
 Governed by a flexible programming system
 Equipped with a modifiable control unit

 no human intervention

Electromagnetic relay

Joseph Henry 1797 - 1878

The electronic revolution
Edison effect (1883)
electric current passes from hot to cold electrode in a vacuum electrons are expelled from the hot wire
Thomas A. Edison 1847 - 1931

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


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


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

Electro-mechanical calculation

 Zuse
 Stibitz

 Aiken
Based on electro-magnetic relays

George Stibitz
Bell Laboratories
 Model K literally built in his kitchen – 1937  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  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 105 connections

Howard Aiken
1900 -1973

 Although inspired by Babbage, it had no conditional branching

Automatic Sequence Controlled Calculator

Harvard Mark I

John Vincent Atanasoff
1903-1995 first general-purpose electronic digital computer

J. Atanasoff and C. Berry

The ABC Machine
problems involving systems of simultaneous linear equations never finished !

 Binary digits to represent all numbers and

 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 1905-1998 Alan Turing M.H.A. Newman  assisted the codebreaking efforts at Bletchley Park
 first digital (partially) programmable, electronic computer

 Completed in 1943

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

Electrical Numerical Integrator and Calculator
ballistic tables
weather prediction

 atomic-energy calculations  cosmic-ray studies  thermal ignition  random-number studies  wind-tunnel design


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

1912-1954 « 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

The Turning Test

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