INTRODUCTION TO COMPUTERS
INTRODUCTION TO COMPUTERS
After completing this unit, you will be able to:
· Understand the parts of a computer system.
· Understand the various Types of Computer Hardware.
· Understand the units of measure for Computer Memory and Storage.
· Understand Input and Output Devices.
· Understand Storage Devices.
· Understand the different Computer software available.
1.2 Essential Elements of a Computer
1.3 Types of Hardware
1.4 Types of Software
1.5 Types of Computers
1.6 History of Computers
1.8 Self-Assessment Questions
days, it has become almost mandatory to have a general understanding of
computers, its capabilities as well as its limitations. You need to
know how to work with a computer by using pre-written instructions and
commands that cause the machine to produce the results you desire. You
may be surprised to know that much of your future work activity can be
anticipated now, and that your career choice may make little difference
in the accuracy of the forecast. In the 1950s, people considered
computers to be large and costly. They thought that these machines would
have little impact on their lives. In the 1960s, their thinking started
changing. In the 1970s, organizations replaced their old and bulky
computers with new versatile ones as they started realizing the benefits
that could be accrued from them. By the mid-1980s, personal computers
had flooded all types of organizations. Today, hospitals, supermarkets,
provision stores, banks, business organizations, offices, factories,
schools and numerous other institutions use computers for improving
their productivity as well as for exercising better control on men,
machinery and finances. Almost each and every section of society today
is becoming more and more dependent on computers and information
1.2 ESSENTIAL ELEMENTS OF A COMPUTER
computer is an electronic device used to process data. A computer can
convert data into information that is useful to people. A computer is a
programmable machine that manipulates raw, facts according to a set of
instructions that are fed into it. A computer is a machine and all the
other equipment associated with it constitute its hardware components.
term computer is a general term that refers to an electronic data
processing machine used by several persons to produce desired results as
and when required. A Personal Computer (PC) refers to an electronic
data processing machine meant for individual use. The instructions that
direct the PC as to what it should do is called software. A set of instructions that perform a particular task is called the program,
or software program. The instructions in the program direct the
computer to perform input operations, process the data and output the
results. The two basic types of computers are the analog and the digital computer. When talking about computers, we mostly refer to the digital type of electronic machines.
There are two basic kinds of computers: analog and digital.
computers are analog devices. They have continuous states rather than
discrete numbered states. An analog computer can represent fractional
irrational values exactly, with no rounding-off. Analog computers are
usually used to process analog data and needs high processing capacity
and a focused setup for it.
Digital computers are programmable
machines that use discrete states. A binary digital computer uses two
discrete states, such as positive/negative, high/.low or on/off, used to
represent the binary digits zero and one. Nowadays, most of the
computers are of a digital type as it is more flexible and can be easily
adapted in our routine work.
CHARACTERISTICS OF COMPUTERS
Computers display the following characteristics depending on their type and use:
1. The ability to perform calculations at a fast speed and to store that information for future retrieval or use.
2. The ability to take in information and to store that information for future retrieval or use.
3. The ability to take in and store a small variety of instructions for computers to obey.
The ability to use simple logical rules to make decisions for their own
internal control or for the control of some external activity.
5. The ability to communicate with other computer systems.
6. It has high diligence power.
7. It is known for accurate result. (Note: The accuracy of the the results is based on the accuracy of the input)
Computers are programmable to perform certain task, due to this feature
they are more popular and are implemented in almost all of the area
where data processing is required.
Part of Computer System
computer’s hardware consists of electronic devices; the parts you can
see and touch. The term “device” refers to any piece of hardware used by
the computer, such as a keyboard, monitor, modem, mouse, etc.
also called as programs, consists of Software, also called as programs,
consists of organized sets of instructions for controlling computer
operations. Some programs exist for the computer’s use, to help it
manage its own tasks and devices.
Other programs exist for the
user, and enable the computer to perform tasks for you, such as creating
documents, deleting documents, etc.
consists of raw facts and figures which the computer can manipulate and
process into information that is useful to people. Computerized data is
digital, meaning that it has been reduced to digits or numbers. The
computer stores and reads all data as numbers. Although computers use
data in digital form, they convert data into forms that people can
understand, such as text, numerals, sounds and images.
People are the computer's operators or users.
types of computers can operate without much intervention from people;
however personal computers are designed specifically for users.
1.3 TYPES OF HARDWARE
Computer's hardware devices are categorized as follows:
1. Processor (CPU)
3. Input and Output (I/O) Devices
4. Storage Devices
1. Processor ( central Processing Unit)
processor is the part of the computer that actually does the
computations. The procedure that transforms raw data into useful
information is called processing. This function is
divided between the computer’s processor and memory. The processor which
is called the central processing unit (CPU) is also called as the brain
of the computer. CPU controls each and every action of every component
connected to it to make up the computer as a whole. It manages all
devices and performs the actual processing of data. The CPU consists of
one or more chips attached to the computer’s main circuit board (the
motherboard). Some computers have more than one processor. This is
The major kinds of digital processors are CISC, RISC, DSP and Hybrid.
for Complex Instruction Set Computer. Mainframe computers and
minicomputers are CISC processors, with manufacturers competing to offer
the most useful instruction sets. Many of the first two generations of
microprocessors were also CISC.
RISC stands for
Reduced Instruction Set Computer. RISC came about as a result of
academic research that showed that a small well-designed instruction set
running compiled programs at high speed could perform more computing
work than a CISC running the same programs (although very expensive).
stands for Digital Signal Processing. DSP is used primarily in
dedicated devices such as modems, digital cameras, graphics cards and
other specialty devices.
Hybrid processors combine elements of two or three of the major classes of processors.
also consists of chips attached to the motherboard. The memory holds
data and program instructions as the CPU works with them. This memory is
called Random Access Memory (RAM).
The CPU can find any piece
of data in the RAM as and when it needs it for processing. RAM is
volatile, meaning it holds data only when the power is on; as soon as
the power is off, the data which it holds is also erased automatically.
RAM, Random Access Memory, is a kind of internal memory available, which the CPU
can access at any time whenever required. RAM is called “random access”
because the processor or computer can access any location in the memory
whenever required. RAM has been made from reed relays,
transistors, integrated circuits, magnetic core or anything that can
hold and store binary values (one/zero, plus/minus, open/close,
positive/negative, high/low, etc.). Most modem RAM is made from
RAM is available as Static RAM and Dynamic RAM.
Static RAM is called static because it will continue to hold and store
information even when the power is cut off or removed. Magnetic core and
reed relays are examples of static memory. Dynamic RAM is called
dynamic because it loses all data when the power is removed. Transistors
and integrated circuits are examples of dynamic memory. It is possible
to have battery backup for devices that are normally dynamic so as to
turn them into static memory.
ROM is Read Only
Memory (it is also random access, but only for reading). ROM is
typically used to store things that will never change for the life of
the computer, such as low level portions of an operating system. Some
processors (or variations within processor families) might have RAM
and/or ROM built into the same chip as the processor (normally used for
processors used in standalone devices, such as arcade video games, ATMs,
microwave ovens, car ignition systems, etc.). EPROM is
Erasable Programmable Read Only Memory, a special kind of ROM that can
be erased and reprogrammed with specialized equipment (but not by the
processor it is connected to). EPROMs allow makers of industrial devices
(and other similar equipment) to have the benefits of ROM, yet also
allow for updating or upgrading the software without having to buy new
ROM and throw out the old (the EPROMs are collected, erased and
rewritten centrally, and then placed back into the machines).
smallest usable unit of measure for memory is the byte which is the
amount of memory required to hold one character, like the letter of the
alphabet A or the numeral 2.
|Approximate Value (bytes)||Actual Value (bytes)||Unit|
3. Input and Output Devices
devices are devices that bring information into a computer. Input
devices accept data and instructions from the user or from another
computer system. The keyboard and mouse are examples of input devices.
Pure input devices include such devices as punched card readers, paper
tape readers, keyboards, mouse, drawing tablets, touch pads, trackballs
and game controllers. Input devices act as a feeding unit to the CPU for
Output devices are devices that bring information
out of a computer. Output devices return processed data back to the user
or to another computer system. The printer and monitor are examples of
output devices. Pure output devices include such devices as card
punches, paper tape punches, LED displays (for light emitting diodes),
monitors, printers and pen plotters. The output unit is responsible for
displaying the required information in the desired format to the user.
devices (such as modems and network interface cards) perform both input
and output functions allowing computers to share information. External
modems are communication devices that computers utilize to connect to
public networks like the Internet, A modem that sits inside the computer
is called an internal modem, while modems that sit outside the computer
are external modems. The type of modem you require
depends on the type of Internet access service you desire. There are two
general categories: Basic dial-up service and high-speed broadband
In order for a computer to be able to talk to other
computers or to an Internet service provider, it needs what is called a
Network Interface Card or NIC. This card, usually found
inside the computer, is the gateway into which you plug an Ethernet
cable. The Ethernet cable resembles a telephone wire, though slightly
larger in diameter and its end is about twice the size of a standard
RJ11 jack. An Ethernet cable is standard for connecting your computer to
a high-speed Internet modem, or to a network within your home.
4. Storage Device
devices hold data not currently being used by the CPU. Data is commonly
stored o a magnetic or optical disk. Each type uses a special medium
for storing data on its surface. A disk drive is a device that reads
data from and writes data onto a disk. Most new computer feature a
floppy disk drive, a hard disk drive and an optical disk drive.
The most common optical storage devices are CD-ROM and DVD-ROM drives.
1.4 TYPES OF SOFTWARE
is a set of electronic instructions that tells the computer how to do
certain tasks. A set of instructions is often called a program.
When a computer is using a particular program, it is said to be running or executing the program.
The two most common types of programs are system software and application software.
1. System Software
software exists primarily for the computer itself, to help the computer
perform specific functions. One major type of system software is the
operating system (OS). All computers require an operating system.
OS tells the computer how to interact with the user and its own
devices. Common operating systems include Windows, the Macintosh OS,
OS/2, and UNIX. Basically one can conclude that system software is
software which manages the memory, the processes and the files created
by the user.
operating system is a complex series of programs, which controls the
overall operations of a computer. It makes the power of the computer
available to users. It allows users to communicate with a computer. It
permits users to create files, use and control input/output devices and
execute programs. MS-DOS is a single user operating system developed by
Microsoft (a software company). MS-DOS stands for Microsoft Disk
Operating System. It is widely used for personal computers PC, PC/XT and
PC/AT. PC-DOS is the IBM version of this operating system. OS/2 is a
multitasking operating system developed by Microsoft and IBM. It is used
for personal computers PS/2 and PC/AT. UNIX is a multitasking and
multi-user operating system developed by Bell Telephone Research
Laboratory. It is used with mainframe, mini and powerful 32-bit personal
computers. XENIX is a version of UNIX, developed by Microsoft. It is a
widely used multi-user operating system. FINDER is an operating system
for icon/mouse oriented personal computers such as Macintosh. RMX 86 is a
multitasking operating system for real-time control in an industrial
environment. In an industry, a number of tasks are performed on the
basis of priority. The time-slice approach of UNIX is quite suitable for
multi-user tasks but not suitable for priority oriented multitasking
operations. RMX 86 has been developed by Intel for this type of
environment. Windows 3.1 and Windows 95 Windows is a relatively recent
operating system environment for PCs, developed by Microsoft
Corporation. It provides Graphical User Interface (GUI). Earlier,
graphical user interface was treated as a luxury and was not available
to persons working in business environments with PCs. It was available
to persons working on mini and large computers and desktop publishing
systems. Today, almost all environments related to management, finance,
sales, marketing, development and other general office functions need a
rapid access to information. They also need powerful tools to
manipulate, analyze, exchange and present information. Windows with its
graphical user interface facility is capable of meeting these
2. Application Software
software tells the computer how to accomplish tasks the user requires,
such as creating a document or editing a graphic image.
Some important kinds of application software are:
a. Word processing programs
b. Spreadsheet software
c. Database management
d. Presentation programs
e. Graphics programs
f. Networking software
g. Web design tools and browsers
h. Internet applications
i. Communications programs
k. Entertainment and education
l. Multimedia authoring
1.5 TYPES OF COMPUTERS
Computers can either be classified according to their size or their processing mode.
The different types of computers are as follows:
3. Mainframe computers
microcomputer is a low-cost, small, digital computer. It contains a
microprocessor as its CPU, a memory unit, an input device and an output
device. The word length of a microcomputer lies in the range 8-32 bits.
Microcomputers have a wide range of applications. A few examples are:
general purpose calculations, industrial control, instrumentation, home
appliances, commercial equipment control, fuel injection control of a
car, office automation, etc. PCs and PS/2 are microcomputers for general
purpose computations. Users can work on PCs and PS/2 in high-level
languages such as BASIC, FORTRAN, COBOL, PASCAL, etc. Popular
application packages such as word processing, spreadsheet, database
management, graphics, accounting packages, etc. also run on PCs and
work faster and have more powerful CPUs than microcomputers. Their word
length is 32 bits. Most minicomputers use Motorola 68030 or 68040 CPU.
Some minicomputers are uni-processor systems whereas some are
multiprocessor systems. The processing speed lies in the range 10-30
MIPS and Memory (RAM) capacity lies in the range 8-96 M bytes. In some
systems it can be extended up to 128-256 M byte. The hard disk capacity
lies in the range 380-3 Gigabytes (GB). A minicomputer can support up to
64 or even more terminals. Minicomputers are extensively used for
payroll preparation, accounting and scientific computation.
High-performance workstations with graphics input/output capability use
minicomputers. Minicomputers are used for multi-user and interactive
applications in colleges, universities, research organizations,
government organizations and industries. They are also used for
real-time (industrial) controls and engineering design work.
Minicomputers support a greater variety of peripheral devices.
Examples of minicomputers are:
VAX 8842 (VAX stands for Virtual Address Extension and are manufactured by Digital Equipment Corporation).
WIPRO S-68030V and S-6833V built around 68030 CPU.
WIPRO LANDMARK 860 (a supermini) built around Intel i860 CPU (a 64-bit RISC processor).
HP 9000 series 800 (super mini) built around Hewlett Packard's VLSI RISC processor.
HCL magnum built around 68030 CPU, and 68040.CPU.
3. Mainframe Computers
computers are very powerful large general purpose computers. They are
faster and more powerful than minicomputers. Their word length may be
48, 60 or 64 bits memory capacity, 64-256 M byte, hard disk capacity, I -
10 G byte or more, and processing speed, 30-100 MIPS. They are used
where large amounts of data are to be processed or very complex
calculations are to be made, and these tasks are beyond the computing
capacity of minicomputers. They are used in research organizations,
large industries, large business and government organizations; banks and
airline reservations where a large database is required. Examples of
mainframe computers are:
IBM 4300 series (small to medium size models)
IBM 308X series (large models)
IBM 3090 series
are much faster and more powerful than main-frame computers. Their
processing speed lies in the range 400-10,000 MIPS, word length 64-96
bits, memory capacity 256M byte and more, hard disk capacity 1000M byte
and more, and machine cycle time 4-6 nano second (ns). Supercomputers
are specially designed to maximize the number of floating point
instructions per second (FLOPS) which is usually more than 1 gigaflop
per second. A supercomputer contains a number of CPUs which operate in
parallel to make it faster. They are used for massive data processing
and solving very sophisticated problems. They are used for weather
forecasting, weapons research and development, rocketing, aerodynamics,
seismology, atomic, nuclear and plasma physics.
Examples of supercomputers are:
CRAY 3, (developed by Control Data Corporation)
SX-2 (developed by Nippon Electric Corporation, Japan)
SX-3R (25.6 GIGAFLOPS, NEC make)
ITAC S-300 (32 GIGAFLOPS, Hitachi make) HITAC S-300 is the latest and
fastest supercomputer. The cycle time of a supercomputer may be as low
as 4 ns. In a single machine cycle, two 64-bit data can be added.
Supercomputers have a limited use and limited market because of their
very high price. They are being used at some research centres and
government agencies involving sophisticated scientific and engineering
1.6 HISTORY OF COMPUTERS
first computing machine, called the abacus, was invented around 5,000
years ago and surprisingly is still in use today. This device allows
users to make computations using a system of sliding beads arranged on a
rack. Let us now look at the interesting history of computers:
In the 1600s:
next major advancement in computers came around the mid-1600s.Blaise
Pascal, a tax officer working on taxes for the French Government,
decided in 1642 to build an adding and subtracting machine to help him
figure the taxes. The machine was called the ‘Pascaline’ and consisted
of eight gears that worked to calculate numbers. The machine encountered
many problems and was always breaking down.
In the 1800s:
real beginning of computers as we know them today came about in the
early 1800s, with a British Mathematics Professor named Charles Babbage.
He worked on two machines: the Analytical Engine and the Difference
Engine. These machines were amazingly similar to the computers we know
today. The machines were meant to read a program from punched cards,
figure out and store the answers to different problems, and then print
the answers on paper. Due this remarkable work, Charles Babbage is known
as the ‘Father of Computers’.
In the early 1900s:
next huge step for computers came with the invention of a machine which
was capable of counting and recording information faster. This machine
was called the ‘Tabulating Machine’ that read and sorted data from
punched cards. Thanks to this machine, instead of taking seven and a
half years to count the census information, a government is likely to
take only three years.
Table 1.2 Generations of Electronic Computers
|Generation||First Generation –I||Second Generation II||Third Generation III||Fourth Generation IV |
|Technology||Vacuum Tubes||Transistors||Integrated Circuits (multiple transistors)||Microchips (million of transistors)|
|Size||Filled an entire Building||Filled half a room||Smaller||Tiny-Palm Pilot is as powerful as the old building-sized computer|
The First Generation Computers: 1946-1956
first generation computers were huge, slow, expensive and often
undependable. They were characterized by having vacuum tubes that were
often very big and gave off much heat. The invention of the vacuum tube
was an extremely important step in the advancement of computers. Vacuum
tubes were very similar to light bulbs. Their purpose was to act like an
amplifier and a switch, and could also stop and start the flow of
In 1946, J. Presper Eckert, and John Mauchly built the ENIAC
(Electronic Numerical Integrator and Computer). This was an electronic
computer that used thousands of vacuum tubes, which took up a lot of
space and gave off a great deal of heat. The ENIAC led to other vacuum
tube type computers like the EDVAC (Electronic Discrete Variable Automatic Computer) and the UNIVACI (Universal Automatic Computer).
The Second Generation: 1957-1963
second-generation computers used transistors instead of vacuum tubes.
The transistor was much faster, reliable, smaller and cheaper to build
than the previous vacuum tubes. Transistors were also found to conduct
electricity faster and better than vacuum tubes. They were also much
smaller and gave off virtually no heat as compared to the big vacuum
tubes. Transistors were a tremendous breakthrough in the evolution of
The Third Generation: 1964-1970
integrated circuit, also called the semiconductor chip, is a single
silicon chip packed with hundreds of transistors. The idea of placing
such large number of transistors on a
single chip increased the power
of a single computer and lowered its cost considerable. Ever since this
invention, the number of transistors that can be placed on single chip
further doubled every two years and the size and cost of computers have
decreased even further.
The Fourth Generation: 1971-Today
monolithic integrated circuit is an invention that put millions of
transistors onto one integrated circuit chip (as opposed to just
hundreds). By putting millions of transistors onto one single chip, more
calculations and faster speeds could be reached by computers, However,
what really triggered the tremendous growth of computers and its
significant impact on our lives is the invention of the microprocessor
(a single chip that could do all the processing of a full-scale
A chip, the size of a pencil eraser that could do all
the computing and logic work of a computer called the microprocessor
was made to be used in calculators, not computers. It led to the
invention of personal computers or microcomputers.
The Fifth Generation: The Future
computers of the next generation will have millions upon millions of
transistors on one chip and will perform over a billion calculations in a
single second. The next generation of computers is also exploring
artificial intelligence and is moving rapidly ahead. Obviously, there is
much more to come in the future of computers and one can only guess
what will come next. Let us wait and watch!
this unit, you have studied about the basics of computers, the elements
which include data, users, hardware and software. You should now be
comfortable with the basic concepts and evolution of computers.
A computer is an electronic device capable of fast processing.
An analog computer
can represent fractional or irrational values exactly, with no
round-off required. Analog computers are usually used to process analog
data and need high processing capacity and a focused setup for it.
A digital computer on
the other hand is a programmable machine. A digital computer uses
discrete states. A binary digital computer uses two discrete states,
such as positive/negative, high/low, on/off, used to represent the
binary digits zero and one.
Hardware is anything around the computer which is associated with the PC and can be touched and felt such as the keyboard and mouse.
Software is a logical entity which is usually a set of programs guiding the computer to perform certain tasks.
Data is a collection of facts, figures and symbols which is usually an input to the computer for processing information.
Users are usually the computer operators.