J. Lyons accounting office
1900
Analytical Calculation
 Reduce a problem to a
then a 3rd
nd
2
 Application of rules and
procedures
 Problem is solved by the
machine itself
and
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
1907
Triode
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
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 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
Colossus
 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
Eniac
 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