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Evolution of Computers
The growth of computer industry started with the
need for performing fast calculations.
The manual method of computing was slow and prone to
errors. So attempts were
made to develop faster calculating devices. The
journey that started from the first
calculating device i.e. Abacus has led us today to
extremely high speed calculating
devices. Let us first have a look at some early
calculating devices and then we will
explore various generations of computer.
Abacus
Abacus was discovered by the Mesopotamians in around
3000 BC. An abacus consisted
of beads on movable rods divided into two parts.
(Fig-1) Addition and multiplication of
numbers was done by using the place value of digits
of the numbers and position of
beads in an abacus.
The Chinese further improved on the abacus so that
calculations could be done more
easily. Even today abacus is considered as an apt
tool for young children to do
calculations. In an abacus, each row is thought of
as a ten’s place. From right to left ,
row no-1 represents the one’s column and the second
column represents ten’s place.
The third column represents the hundred’s place and
so on. The starting position of the
top beads (representing the value of five) is always
towards the top wall of the abacus
while the lower beads (representing the value of
one) will always be pushed towards
the lower wall as a starting position.
Napier’s Logs and Bones
The idea of logarithm was developed by John Napier
in 1617. He devised a set of
numbering rods known as Napier’s Bones through which
both multiplication and
division could be performed. These were numbered
rods which could perform
multiplication of any number by a number in the
range of 2-9. There are 10 bones
corresponding to the digits 0-9 and there is also a
special eleventh bone that is used to
represent the multiplier. By placing bones
corresponding to the multiplier on the left
side and the bones corresponding to the digits of
the multiplicand on the right , the
product of two numbers can be easily obtained.
Pascaline
Blaise Pascal, a French mathematician invented an
adding machine in 1642 that was
made up of gears and was used for adding numbers
quickly. This machine was also
called Pascaline and was capable of addition and
subtraction along with carry-transfer
capability. It worked on clock work mechanism
principle. It consisted of various numbered toothed wheels having unique
position values. The addition and subtraction operations was performed by
controlled rotation of these wheels.
Leibnitz’s Calculator
In 1673 Gottfried Leibnitz, a German mathematician
extended the capabilities of the
adding machine invented by Pascal to perform
multiplication and division as well. The
multiplication was done through repeated addition of
numbers using a stepped
cylinder each with nine teeth of varying lengths.
Jacquard’s Loom
In order to make the cotton weaving process
automatic, Joseph Jaquard devised punch
cards and used them to control looms in 1801. The
entire operation was under a
program’s control. Through this historic invention,
the concept of storing and retrieving
information started.
Difference engine and Analytical Engine
Charles Babbage, an English mathematician developed
a machine called Difference
Engine in 1822 which could calculate various
mathematical functions, do polynomial
evaluation by finite difference and theoretically
could also solve differential equations.
Thereafter in 1833, he designed the Analytical
Engine which later on proved to be the
basis of modern computer. This machine could perform
all the four arithmetic
operations as well as comparison. It included the
concept of central processor, memory
storage and input-output devices. Even the stored
information could be modified.
Although the analytical engine was never built that
time but Babbage established the
basic principles on which today’s modern computers
work.
Both these great inventions earned him the title of
‘Father of Modern Computers’.
Mark 1
In 1944 Prof Howard Aiken in collaboration with IBM
constructed an electromechanical
computer named Mark 1 which could multiply two 10
digit numbers in 5 seconds. This
machine was based on the concept of Babbage’s
Analytical engine and was the first
operational general purpose computer which could
execute preprogrammed
instructions automatically without any human
intervention.
In 1945, Dr. John Von Neumann proposed the concept
of a stored program computer.
As per this concept the program and data could be
stored in the same memory unit.
According to Von Neumann architecture, the processor
executes instructions stored in
the memory of the computer. Since there is only one
communication channel, the
processor at a time can either fetch data or an
instruction. That means at one point of
time either the data or an instruction can be picked
(fetched) from the storage unit for
execution by the processor. Hence execution takes
place in sequential manner. This
limitation of Von Neumann Computer is known as Von
Neumann bottleneck. EDVAC
(Electronic Discrete Variable Automatic Computer)
was the first stored program
computer developed in 1952. After the invention of
first electronic computer ENIAC
(Electronic Numerical Integrator and Calculator) in
1946, the computer technology
improved tremendously and at very fast pace.
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