|
|
(
The first computer in the
world was ENIAC (electronic numerical integrator and computer). It was
developed in 1940s and served as the major computation instrument for ballistic
tables for the U.S. Army and Air Force. it was also used for scientific
purposes, such as weather prediction, atomic-energy calculations, and thermal
ignition study. It was the most powerful computer till early 1950s.
ENIAC had an astonishing
speed of 10-microsecond / cycling pulse, i.e. 100Hz (1Hz = 1/1,000,000MHz).
It weighted over 30 tons. It had 19,000 tubes, 1,500 relays, and thousands
of other electronic components. It consumed 200 kilowatts of power supply
to operate.
Changing programming logic
required a large group of people to work for weeks with switches and cables.
In 1936 British mathematician
Alan Turing proposed the idea of a machine that could process equations
without human direction. The machine (now known as a Turing machine) resembled
an automatic typewriter that used symbols for math and logic instead of
letters. Turing intended the device to be used as a "universal machine"
that could be programmed to duplicate the function of any other existing
machine. Turing's machine was the theoretical precursor to the modern digital
computer.
In the 1930s American mathematician
Howard Aiken developed the Mark I calculating machine, which was built
by IBM. This electronic calculating machine used relays and electromagnetic
components to replace mechanical components. In later machines, Aiken used
vacuum tubes and solid state transistors (tiny electrical switches) to
manipulate the binary numbers. Aiken also introduced computers to universities
by establishing the first computer science program at Harvard University.
Aiken never trusted the concept of storing a program within the computer.
Instead his computer had to read instructions from punched cards.
John Mauchley, an American
physicist, and J. Presper Eckert, an American engineer, proposed an electronic
digital computer, called the Electronic Numerical Integrator And Computer
(ENIAC), which was built at the Moore School of Engineering at the University
of Pennsylvania in Philadelphia. The computer was based on some concepts
developed by John Atanasoff, a physics teacher at Iowa State College. ENIAC
was completed in 1945 and is regarded as the first successful, general
digital computer. It weighed more than 27,000 kg (60,000 lb), and contained
more than 18,000 vacuum tubes.
Roughly 2000 of the computer's
vacuum tubes were replaced each month by a team of six technicians. Many
of ENIAC's first tasks were for military purposes, such as calculating
ballistic firing tables and designing atomic weapons. Since ENIAC was initially
not a stored program machine, it had to be reprogrammed for each task.
Unfortunately, although
the conceptual design for EDVAC was completed by 1946, several key members
including Eckert and Mauchley left the project to pursue their own careers,
and
the machine did not become fully operational until 1952. When it was finally
completed, EDVAC contained approximately 4,000 vacuum tubes and 10,000
crystal diodes.
In light of its late completion,
some would dispute EDVAC's claim-to-fame as the first stored-program computer.
A small experimental machine (which was based on the EDVAC concept) consisting
of 32 words of memory and a 5-instruction instruction set was operating
at Manchester University, England, by June 1948. Another machine called
the electronic delay storage automatic calculator (EDSAC) performed its
first calculation at Cambridge University, England, in May 1949.
EDSAC contained 3,000 vacuum
tubes and used mercury delay lines for memory.Programs were input using
paper tape and output results were passed to a teleprinter. Additionally,
EDSAC is credited as using one of the first assemblers called "Initial
Orders," which allowed it to be programmed symbolically instead of using
machine code.
Eckert and Mauchley eventually
formed their own company, which was then bought by the Rand Corporation.
They produced the Universal Automatic Computer (UNIVAC), which was used
for a broader variety of commercial applications. The (UNIVAC I), was also
based on the EDVAC design. Work started on UNIVAC I in 1948, and the first
unit was delivered in 1951, which therefore predates EDVAC's becoming fully
operational.
Eckert and Mauchly later
lost the patent on their machine when it was claimed that another early
experimenter, John Atanasoff, had given them all the ideas about ENIAC
that mattered.