The computer evolution is indeed an interesting topic that
has been explained in some
different ways over the years, by many authors. According to The Computational Science
Education Project, US, the computer has evolved through the
following stages:
The Mechanical Era (1623-1945)
Trying to use machines to solve mathematical problems can be
traced to the early 17th
century. Wilhelm Schickhard, Blaise Pascal, and Gottfried
Leibnitz were among mathematicians who designed and implemented calculators that were capable of addition,
subtraction, multiplication, and division included
.
The first multi-purpose or programmable computing device was probably Charles Babbage's Difference
Engine, which was begun in 1823 but never completed. In 1842, Babbage designed a more
ambitious machine, called the Analytical Engine but unfortunately it also was only
partially completed. Babbage, together with Ada Lovelace recognized several important programming
techniques, including conditional branches, iterative loops and index variables. Babbage designed the machine which is arguably the first to be used in computational
science. In 1933, George Scheutz and his son, Edvard began work on a smaller version of the
difference engine and by 1853 they had constructed a machine that could process 15-digit numbers and calculate fourth-order differences.
The US
Census Bureau was one of the first organizations to use the mechanical
computers which used punch-card equipment designed by Herman
Hollerith to tabulate data for the 1890 census. In 1911 Hollerith's company merged with
a competitor to found the
corporation which in 1924 became International Business
Machines (IBM).
First Generation Electronic Computers (1937-1953)
These devices used electronic switches, in the form of
vacuum tubes, instead of
electromechanical relays.
The earliest attempt to build an electronic computer was by J. V.
Atanasoff, a professor of physics and mathematics at Iowa
State in 1937. Atanasoff set out to
build a machine that would help his graduate students solve systems of partial
differential
equations. By 1941 he and graduate student Clifford Berry
had succeeded in building a machine that could solve 29 simultaneous equations with 29 unknowns. However, the
machine was not programmable, and was more of an electronic
calculator.
A second early electronic machine was Colossus, designed by
Alan Turing for the British
military in 1943. The
first general purpose programmable
electronic computer was the Electronic Numerical Integrator and Computer
(ENIAC), built by J. Presper Eckert and John V. Mauchly at the University of Pennsylvania. Research work
began in 1943, funded by the Army Ordinance Department, which needed a way to compute
ballistics during World War II. The machine was completed in 1945 and it was used
extensively for calculations during the design of the hydrogen bomb. Eckert, Mauchly, and John von Neumann, a
consultant to the ENIAC project, began work on a new machine before ENIAC
was finished. The main contribution of EDVAC, their new project, was the notion of
a stored program. ENIAC was controlled by a set of external switches and dials; to change
the program required physically altering the settings on these controls. EDVAC was able to
run orders of magnitude faster than ENIAC and by storing instructions in the same medium as data, designers could concentrate on improving the internal structure of the
machine without worrying about matching it to the speed of an external control. Eckert and Mauchly later designed what was arguably the first commercially successful computer, the UNIVAC; in 1952. Software technology during this period was very primitive.
Second Generation (1954-1962)
The second generation witnessed several important
developments at all levels of computer
system design, ranging from the technology used to build the
basic circuits to the
programming languages used to write scientific
applications. Electronic switches in
this era
were based on discrete diode and transistor technology with
a switching time of
approximately 0.3 microseconds. The first machines to be
built with this technology include
TRADIC at Bell Laboratories in 1954 and TX-0 at MIT's
Lincoln Laboratory. Index
registers were designed for controlling loops and floating
point units for calculations based
on real numbers.
A number of high level programming languages were introduced
and these include
FORTRAN (1956), ALGOL (1958), and COBOL (1959). Important
commercial machines of
this era include the IBM 704 and its successors, the 709 and
7094. In the 1950s the first two
supercomputers were designed specifically for numeric
processing in scientific applications.
Third Generation (1963-1972)
Technology changes in this generation include the use of
integrated circuits, or ICs
(semiconductor devices with several transistors built into
one physical component),
semiconductor memories, microprogramming as a technique for efficiently designing
complex processors and the introduction of operating systems
and time-sharing. The first ICs were based on small-scale integration (SSI) circuits, which
had around 10 devices per circuit (or ‘chip’), and evolved to the use of medium-scale
integrated (MSI) circuits, which had up to 100 devices per chip. Multilayered printed circuits were
developed and core memory was replaced by faster, solid state memories.
