1.1 BASIC CONCEPTS OF COMPUTER
Computer is a device that computes,
especially a programmable electronic
machine that performs high speed
mathematical or logical operations or that
assembles stores. Correlates, or otherwise
processes information. ‗
Data Processing is a process of
transforming data into useful and meaningful
information. Data is a collection of facts
(numbers, letters, special symbols or
combination of these) relating to events that
take place. Information refers to the data
that has been organized and processed so
that it becomes meaningful.
History of Computing
The earliest computing device undoubtedly consisted of the five fingers of each hand and this is still the preferred
device of every child who learns to count. Since there are ten discrete fingers (digits) available for counting, both digital
computation and decimal system ‗have enjoyed a huge popularity throughout history. However, Improvements were
made to replace the digits of the hand by a more reliable ' count-10 device.
Historical records will tell us that man has invented 3 types of devices to assist him in calculating and processing data,
these devices could be classified into
(a) Manual mechanical
(b) electromechanical and
(c) Electronic.
Manual Mechanical Device
a device with simple mechanism powered by hand. Basically devices of this type required some sort of physical
effort from the user when used
The earliest data processing equipment were all manual mechanical devices due to the absence of electricity and
adequate Industrial technology.
Abacus
The first manual data processing device was the
abacus which was developed in China in the
twelfth century AD. The device has a frame with
beads strong wires on rods and arithmetic
calculations are perform by manipulating beads.
The Chinese abacus is made up of 13 columns
with 2 beads on top (heaven) and 5 beads below
(earth). The Japanese copied the Chinese abacus
around the 17‗" Century A.D. and adopted it to their
more delicate way of thinking. It has 21 Columns
with 1 bead on top and 4 beads below.
Napier’s bones
An arrangements of bones wherein numbers are printed developed
by John Napier who became famous because of his invention of
logarithms. The use of ―logs‖ enabled him to reduce any
multiplication a problem to a problem of addition. Its bones are a set
of eleven rods with numbers marked on them in such a way that by
simply placing the rods side by side products and quotients of large
numbers can be obtained. The sticks were called ―bones" because I
they were made of bone or Ivory. Napier‘s bones I represented a
significant contribution to the development of computing devices.
Pascaline
also called Arithmetic Machine, calculator or adding
machine to be produced in any quantity and actually used. The
Pascaline was designed and built by the French
mathematician-philosopher Blaise Pascal between 1642 and
1644. It could only do addition and subtraction, with numbers
being entered by manipulating its dials. Pascal invented the
machine for his father, a tax collector, so it was the first
business machine too (if one does not count the abacus). He
built 50 of them over the next 10 years.
Leibnitz Calculator
Can multiply, divide, add and subtract.
Mechanical device made of copper and
steel. Carriage is performed with a stepped
wheel, which mechanism is still in use
today. Contrary to Pascal, Leibniz (16461716) successfully introduced a calculator
onto the market. It is designed in 1673 but
it takes until 1694 to complete. The
calculator can add, subtract, multiply, and
divide. Wheels are placed at right angles
which could be displaced by a special
stepping mechanism. The speed of
calculation for multiplication or division was
acceptable. But like the Pascaline, this
calculator required that the operator using
the device had to understand how to turn
the wheels and know the way of performing
calculations with the calculator.
Analytical Engine
Proposed mechanical general-purpose computer designed by
English mathematician and computer pioneer Charles Babbage. It
was first described in 1837 as the successor to
Babbage's difference engine, a design for a simpler mechanical
computer.
The Analytical Engine incorporated an arithmetic logic unit, control
flow in the form of conditional branching and loops, and
integrated memory, making it the first design for a general-purpose
computer that could be described in modern terms as Turingcomplete. In other words, the logical structure of the Analytical Engine was essentially the same as that which has
dominated computer design in the electronic era. The Analytical Engine is one of the most successful achievements of
Charles Babbage.
Babbage was never able to complete construction of any of his machines due to conflicts with his chief engineer and
inadequate funding. It was not until 1941 that the first general-purpose computer, Z3, was built, more than a century
after Babbage had proposed the pioneering Analytical Engine in 1837.

Electronic Device
are components for controlling the flow of electrical currents for the purpose of information processing and system
control. Prominent examples include transistors and diodes. Electronic devices are usually small and can be grouped
together into packages called integrated circuits .
Atanasoff–Berry computer
The Atanasoff–Berry computer was the first automatic
electronic digital computer. Limited by the technology of the
day, and execution, the device has remained somewhat
obscure
The result was ENIAC (Electronic Numerical
Integrator And Computer), built between 1943
and 1945—the first large-scale computer to run at
electronic speed without being slowed by any
mechanical parts. For a decade, until a 1955
lightning strike, ENIAC may have run more
calculations than all mankind had done up to that
point.
COMPUTER GENERATIONS
1940 – 1956: First Generation – Vacuum Tubes
These early computers used vacuum tubes as circuitry and
magnetic drums for memory. As a result they were enormous,
literally taking up entire rooms and costing a fortune to run.
These were inefficient materials which generated a lot of heat,
sucked huge electricity and subsequently generated a lot of
heat which caused ongoing breakdowns.
These first generation computers relied on ‗machine
language‘ (which is the most basic programming language
that can be understood by computers). These computers were
limited to solving one problem at a time. Input was based on
punched cards and paper tape. Output came out on printouts. The two notable machines of this era were the UNIVAC
and ENIAC machines – the UNIVAC is the first every
commercial computer which was purchased in 1951 by a
business – the US Census Bureau.
1956 – 1963: Second Generation – Transistors
The replacement of vacuum tubes by
transistors saw the advent of the second
generation of computing. Although first
invented in 1947, transistors weren‘t used
significantly in computers until the end of
the 1950s. They were a big improvement
over the vacuum tube, despite still
subjecting computers to damaging levels
of heat. However they were hugely
superior to the vacuum tubes, making
computers smaller, faster, cheaper and
less heavy on electricity use. They still
relied on punched card for input/printouts.
The language evolved from cryptic binary language to symbolic (‗assembly‘) languages. This meant
programmers could create instructions in words. About the same time high level programming languages
were being developed (early versions of COBOL and FORTRAN). Transistor-driven machines were the first
computers to store instructions into their memories – moving from magnetic drum to magnetic core
‗technology‘. The early versions of these machines were developed for the atomic energy industry.
1964 – 1971: Third Generation – Integrated Circuits
By this phase, transistors were now being miniaturised and
put on silicon chips (called semiconductors). This led to a
massive increase in speed and efficiency of these
machines. These were the first computers where users
interacted using keyboards and monitors which interfaced
with an operating system, a significant leap up from the
punch cards and printouts. This enabled these machines to
run several applications at once using a central program
which functioned to monitor memory.
As a result of these advances which again made machines
cheaper and smaller, a new mass market of users emerged
during the ‗60s.
1972 – 2010: Fourth Generation – Microprocessors
This revolution can be summed in one word: Intel. The chip-maker
developed the Intel 4004 chip in 1971, which positioned all computer
components (CPU, memory, input/output controls) onto a single chip. What
filled a room in the 1940s now fit in the palm of the hand. The Intel chip
housed thousands of integrated circuits. The year 1981 saw the first ever
computer (IBM) specifically designed for home use and 1984 saw the
MacIntosh introduced by Apple. Microprocessors even moved beyond the
realm of computers and into an increasing number of everyday products.
The increased power of these small computers meant they could be linked, creating networks. Which
ultimately led to the development, birth and rapid evolution of the Internet. Other major advances during this
period have been the Graphical user interface (GUI), the mouse and more recently the astounding advances
in lap-top capability and hand-held devices.
2010- Future : Fifth Generation – Artificial Intelligence
Computer devices with artificial intelligence are still in
development, but some of these technologies are beginning to
emerge and be used such as voice recognition.
AI is a reality made possible by using parallel processing and
superconductors. Leaning to the future, computers will be
radically transformed again by quantum computation, molecular
and nano technology.
The essence of fifth generation will be using these technologies
to ultimately create machines which can process and respond to
natural language, and have capability to learn and organise
themselves.
ELEMENTS OF COMPUTER
Computer system is a set of integrated devices that input, output, process, and store data and
information. Computer systems are currently built around at least one digital processing device. There are
five main hardware components in a computer system: Input, Processing, Storage, Output and
Communication devices.
Hardware:
The physical components of a computer constitute its Hardware. These include
keyboard, mouse, monitor and processor. Hardware consists of input devices and
output devices that make a complete computer system.
Examples of input devices are keyboard, optical scanner, mouse and joystick which are
used to feed data into the computer. Output devices such as monitor and printer are
media to get the output from the computer.
Input Unit:
Input unit is responsible for controlling the various input devices that
are used to enter data into the computer. The commonly used input devices
are mouse, keyboard, light pen, optical scanner etc. While some input
devices are designed for special purposes such as Optical Character
Recognition (OCR), Magnetic Ink Character Recognition (MICR) and Bar
Code Reader etc, there are other devices that accept input by responding to
physical touch and voice such as ATMs.
Keyboard
Keyboard is the most common and very
popular input device which helps to input data
to the computer. The layout of the keyboard
is like that of traditional typewriter, although
there are some additional keys provided for
performing additional functions.
Mouse
Mouse is the most popular pointing device. It is a very
famous cursor-control device having a small palm size box
with a round ball at its base, which senses the movement
of the mouse and sends corresponding signals to the CPU
when the mouse buttons are pressed.
Generally, it has two buttons called the left and the right
button and a wheel is present between the buttons. A
mouse can be used to control the position of the cursor on
the screen, but it cannot be used to enter text into the
computer.
Light Pen
Light pen is a pointing device similar to a pen. It is used to select a displayed
menu item or draw pictures on the monitor screen. It consists of a photocell
and an optical system placed in a small tube.
When the tip of a light pen is moved over the monitor screen and the pen
button is pressed, its photocell sensing element detects the screen location
and sends the corresponding signal to the CPU.
Joystick
Joystick is also a pointing device, which is used to move the cursor position on a
monitor screen. It is a stick having a spherical ball at its both lower and upper ends.
The lower spherical ball moves in a socket. The joystick can be moved in all four
directions.
The function of the joystick is similar to that of a mouse. It is mainly used in
Computer Aided Designing (CAD) and playing computer games.
Track Ball
Track ball is an input device that is mostly used in notebook or laptop
computer, instead of a mouse. This is a ball which is half inserted and by
moving fingers on the ball, the pointer can be moved.
Since the whole device is not moved, a track ball requires less space
than a mouse. A track ball comes in various shapes like a ball, a button,
or a square.
Scanner
Scanner is an input device, which works more like a photocopy machine. It is
used when some information is available on paper and it is to be transferred
to the hard disk of the computer for further manipulation.
Scanner captures images from the source which are then converted into a
digital form that can be stored on the disk. These images can be edited before
they are printed.
Microphone
Microphone is an input device to input sound that is then stored in a
digital form.
The microphone is used for various applications such as adding sound
to a multimedia presentation or for mixing music.
Bar Code Readers
Bar Code Reader is a device used for reading bar coded data (data
in the form of light and dark lines). Bar coded data is generally used
in labelling goods, numbering the books, etc. It may be a handheld
scanner or may be embedded in a stationary scanner.
Bar Code Reader scans a bar code image, converts it into an
alphanumeric value, which is then fed to the computer that the bar
code reader is connected to.
Output Unit:
It controls various output devices like printer, graphic plotter, speech synthesizer,
monitor (also known as Visual Display Unit or VDU) to produce the desired output and
present it to the user. It ensures the convertibility of output into human readable form
that is understandable by the user.
Monitors
Monitors, commonly called as Visual Display
Unit (VDU), are the main output device of a computer.
It forms images from tiny dots, called pixels that are
arranged in a rectangular form. The sharpness of the
image depends upon the number of pixel
Printers
Printer is an output device, which is used to print information on paper.
There are two types of printers −

Impact Printers

Non-Impact Printers