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and therefore, not computable. A major
development in computing.
Turing was seven years later to work on
the design of COLOSSUS, one of the first
working programmable digital computers. Two years after Turing, in 1939, the world was to see its celebrated
first digital computer developed by John Vincent Atanasoff, a
lecturer at Iowa State College (now University).
Atanasoff’s computer was the first special –purpose electronic digital
computer. Working with his graduate assistant Clifford Berry,
Atanasoff designed a device that utilized capacitors to store
electronic charge to represent Boolean numbers 0 and 1 to be used
by the machine in calculations, a major break through in computing
Input and output data was on punched cards and Atanasoff’s magic
was in creating a storage representation for intermediate data in the
machine as it is used by the digital machine for calculations before it
is output on the punched cards and tape. There is doubt, however,
whether Atanasoff’s model ever worked.
Around the same time Atanasoff and Berry were working on their
model in 1939, Howard Aiken, a graduate of Harvard University,
was developing the first large scale automatic digital computer.
Aiken’s computer came to be known as the Harvard Mark I (also
known as IBM automatic sequencer calculator- ASCC) The next ten years saw the development of the actual working
models of the digital computer as we know it today.
In 1943, Alan Turing, working as a cryptographer, constructed the
COLOSSUS, considered by many as the world’s earliest working
programmable electronic digital computer. The COLOSSUS,
designed to break the German ENIGMA code, used about 1800
vacuum tubes and it was to execute a variety of routines.
Around the time the COLOSSUS was being developed by Alan
Turing, a team of John William Mauchly and J. Presper Eckert Jr.,
working at the University of Pennsylvania, was developing another
vacuum tube-based general purpose electronic digital computer.
Their model named electronic numerical integrator and computer,
(ENIAC) was 10 feet high, weighed 30 tons, occupied 1000
square feet, and used about 70,000 resistors, 10,000 capacitors,
6000 switches, and 18,000 vacuum tube.
After ENIAC went in use, the team encountered a number of
problems the main being that it did not have an internal memory
because it was hard-wired and it was consistently programmed by
switches and diodes. This problem had to be worked on for the next
From 1944 through 1952, the team developed a new computer
called the electronic discrete variable automatic computer – EDVAC. This is believed to be the truly first general purpose digital computer.
EDVAC was a stored-program computer with internal read-write
memory to store program instructions.
The stored program concept gave the device the capability for the
program under execution to branch to alternative instruction sequences
elsewhere in the stored program.
When it was completed...
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