J. Lyons accounting office 1900

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J. Lyons accounting office1900
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Analytical Calculation

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

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Analytical Calculator

• Governed by a flexible programming system
• Equipped with a modifiable control unit
• no human intervention

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Electromagnetic relay
Joseph Henry1797 - 1878
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The electronic revolution

• Edison effect (1883) electric current passes
  from hot to cold electrode in a vacuumelectrons
  are expelled from the hot wire

Thomas A. Edison1847 - 1931
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Flemings valve

• Positively charged metal plate in the tube.
• Free electrons expelled by the heated filament
  all precipitate onto the plate generating
  electric current

diode 1904
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Triode

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

1907
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Flip-flop device dual triode

• Bistable electronic device
• Incoming current flips both triodes into an
  opposite state

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Electro-mechanical calculation

• Zuse
• Stibitz
• Aiken

• Based on electro-magnetic relays

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George StibitzBell 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

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Zuse German Pioneer
Patent applied for 1936
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Claude Shannon

• described the similarity between symbolic logic
  and switching circuits 
• In 1936, he coined theterm bit from binary
  digit, the smallest particle of computer
  information

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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

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Automatic Sequence Controlled Calculator
Harvard Mark I
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John Vincent Atanasoff1903-1995first
general-purpose electronic digital computer
J. Atanasoff and C. Berry
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The ABC Machineproblems involving systems of
simultaneous linear equationsnever 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

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The ABC Machine

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

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Colossus designed byThomas Harold FlowersAlan
TuringM.H.A. Newman
1905-1998

• assisted the code-breaking efforts at Bletchley
  Park
• first digital (partially) programmable,
  electronic computer
• Completed in 1943

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Bletchley Park

• British decoded 75,000 of the 80,000messages
  they intercepted

World War II
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Colossus

• Capable of performing binary logic calculation
• Capable of conditional branching
• Capable of automatically printing
• Capable of storing programalready written for
  the purpose of executing pre-selected functions

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Electrical Numerical Integrator and Calculator

• ballistic tables
• weather prediction
• atomic-energy calculations
• cosmic-ray studies
• thermal ignition
• random-number studies
• wind-tunnel design

Eniac
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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

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None of these machines was a true computer

• All closely resembled Babbages Analytical engine
• Program executed independently of results
• Process could not change in function of the
  results

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Alan Mathison Turing1912-1954
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
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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

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The Turning Test