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1.1. Definition of Computing and Computer
Definition of computing
Computing is a process in which a person or a computer perform mathematical or procedural
tasks.
It is simply the process or act of calculation, Computers are named for this process
It is the use of a computer to process data or perform calculations.
It is the Action of using (a) computer(s) or the use and operation of computers
Generally, Computing in its broadest definition is the study of computers; how they work; how
to design and build them; algorithms and data structures required in order to make timely
computations; how to write programs; and how to apply computer devices to real world
problems and many other aspects.
I.e., Computing includes
Designing and building hardware and software systems for a wide range of
purposes;
Processing structuring, and managing various kinds of information;
Doing scientific studies using computers;
Making computer systems behave intelligently;
Creating and using communications and entertainment media;
Finding and gathering information relevant to any particular purpose, and so on
Computer science needs its own special devices like chemistry has “ test tube ” for its practical
aspect. This device is called computer.
Definition of computer
WHAT IS COMPUTER?
Computer science or Computin g needs its own special devices like chemistry has “test tube” for
its practical aspect. This device is called computer.
The term Computer is derived from the Latin word “ compute ” which means to calculate.
- A computer is an electronic device that can
- Accept input data
- Process arithmetic and logical operations and
- Produce an output or result
A computer is a programmable machine that receives input, stores and manipulates data, and
provides output in a useful format which means computer is both the combination of a
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programmable part and machine part. In regards to today’s computers, the “ machine” part of the
computer is called the hardware , while the “ programmable ” part is called the software. It is
simply composed of hardware & software.
A computer is an electronic machine, devised for performing calculations and controlling
operations that can be expressed either in logical or numeric terms. Or A computer is an
electronic device designed to accept data or instruction (input), performs prescribed
mathematical & logical operations at high speed (processing) and supply the results of these
operations to the outside world (output) or store the data.
In simple words it is an electronic device that performs mathematical & logical operations with
the help of instructions to process the information in order to achieve the desired results
Generally, a computer is an electronic device that takes an input, process it under a set of
instructions called program , produce an output and store the result for future use. Why we need
computer is that if we want some problems to be solved, in nowadays computers can solve
problems if the problem can be solved in to logical steps. Computer is a very powerful and
useful tool which can perform highly complex tasks based on user instruction.
COMPUTERCOMPUTER is also described as ab acronym or abbreviation word
C = C
C = C
ommonly
ommonly ,/C
,/C
omplicated
omplicated
O = O
O = O
riented
riented , /O
, /O
perating
perating ,/O
,/O
ffice
ffice
M = MM = M achineachine
P = P
P = P
articularl
articularl y /P
y /P urely
urely =Mostly
=Mostly
U = U
U = U
sed for
sed for
T = TT = T raderade , / T, / T rainingraining , /T, /T echnologyechnology
E = EE = E ducation andducation and
R = R
R = R
esearch
esearch , /R
, /R
eporting
eporting
CC ommon OO riented MM achine PP articularl yy UU sed for TT rade ,, EE ducation and RR esearch
CC omplicated OO perated Machine PP urely Used for TT raining, Education an RR eporting
Complicated O
O ffice Machine Purely Used for T
T echnology E and Reporting
From these definitions , what a computer in general does is that-
It takes input in various forms from different input units;
Process it according to a given set of instructions called program;
Produce an output in required form such as printed on paper or soft copy and gives it to the
end users;
Storage / keeps the results for future use and later processing and
Controlling /coordinates all the activities inside the computer.
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- In 1621, an English mathematician and clergyman called William Oughtred used
Napier's logarithms as the basis for the slide rule. However, although the slide rule was
an exceptionally effective tool that remained in common use for over three hundred years,
like the abacus it also does not qualify as a mechanical calculator. Not normally used for
addition or subtraction. Slide Rule Used primarily for multiplication, division, roots,
logarithms, and Trigonometry operations or tasks and calculations
- Blaise Pascal is credited with the invention of the first operational calculating machine.
In 1640, Pascal started developing a device to help his father add sums of money. The first
operating model, the Arithmetic Machine, was introduced in 1642. However, Pascal's
device could only add and subtract , while multiplication and division operations were
implemented by performing a series of additions or subtractions. I.e. It was its limitation
to addition and subtraction. The first mechanical adding machine was invented by
Blaise Pascal in 1642
- The first multi-purpose , i.e. programmable , computing device was probably Charles
Babbage's Difference Engine , which was begun in 1823 but never completed. Charles
Babbage is considered to be the father of modern digital computer. A more ambitious
machine was the Analytical Engine. It was designed in 1842, but unfortunately it also was
only partially completed by Babbage. Babbage was truly a man ahead of his time: many
historians think the major reason he was unable to complete these projects was the fact that
the technology of the day was not reliable enough. In spite of never building a complete
working machine, Babbage and his colleagues, most notably Ada , Countess of Lovelace,
recognized several important programming techniques, including conditional branches,
iterative loops and index variables. In 1840, Augusta Ada Byron suggests to Babbage that
he use the binary system. She writes programs for the Analytical Engine.
- A machine inspired by Babbage's design was arguably the first to be used in
computational science. George Scheutz read of the difference engine in 1833, and along
with his son Edvard Scheutz began work on a smaller version. By 1853 they had
constructed a machine that could process 15-digit numbers and calculate fourth-order
differences. Their machine named as Scheutzian Calculation Engine. And it was the first
printing calculator/machine.
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- ENIAC stands for Electronic Numerical Integrator and Computer. It was the first
electronic general-purpose computer Completed in 1946 developed by John Presper
Eckert and John W. Mauchly at the University of Pennsylvania.
- The Universal Automatic Computer ( UNIVAC I ) was the first digital computer .This
machine was one of the first commercial uses of computers was by the US Census
Bureau in 1951. Just like ENIAC it was also designed by John Presper Eckert and John
W. Mauchly
- EDVAC stands for Electronic Discrete Variable Automatic Computer. It was the first
stored program computer designed by Von Neumann in1952. It has a memory to hold
both a stored program as well as data and much more faster than ENIAC
1.3. Generation of Computers
Computer’s efficiency and functionality has been enhanced since the emergence of different
types of computers technologies. This development process can be classified as generations of
computers. ” Generation ” in computer talk is a step in technology or is an enhancement in
technology. The major characteristics that distinguish the various generations are the
following:-
- Dominant type of electronic circuit elements used.
- Major Secondary storage Medias.
- Computer languages used.
- Type or characteristics of operating system used.
- Memory access time / Speed.
Based on the above mentioned basic criteria they are mainly divided into five main generations
First generation – 1946 – 1958/42-
Second generation – 1959 – 1964/55-
Third generation – 1965 – 1970/64-
Fourth generation – 1971 – today/75-
Fifth generation – Today to future
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Third Generation Electronic computers (1964-1975)
Around 1964 Integrated Circuits (ICs) made their appearance and the third-generation
computers were constructed around these ICs. ICs are circuits consisting of several
electronic components like transistors, resistors, and capacitors grown on a single chip of
silicon eliminating wired interconnection between components. ICs were much smaller,
less expensive to produce, more rugged and reliable, faster in operation, dissipated less
heat, and consumed much less power than circuits built by wiring electronic components.
The third-generation computers were thus more powerful, more reliable, less
expensive, smaller, and cooler to operate than the second-generation computers.
Parallel advancements in storage technologies allowed the construction of larger
magnetic cores (magnetic core technology) based memory, and larger capacity
magnetic disks and magnetic tapes. Third-generation computers typically had a few
megabytes (< 5 MB) of main memory and magnetic disks capable of storing a few tens of
megabytes of data per disk drive.
Efforts were made to standardize some of the existing high-level programming
languages like FORTRAN IV and COBOL 68. Programs written with these languages
were thus able to run on any computer that has these compilers. Other high-level
programming languages like PL/1, PASCAL and BASIC were also introduced in this
generation.
Fourth Generation Electronic computers (1975-1989)
The average number of electronic components packed on silicon doubled each year after
- The progress soon led to the era of large scale integration (LSI ) with over 30,
electronic components integrated on a single chip, followed by very large-scale
integration (VLSI) when it was possible to integrate about one million electronic
components on a single chip. This progress led to a dramatic development – the creation
of a microprocessor. A microprocessor contains all the circuits needed to perform
arithmetic and logic operations as well as control functions, the core of all computers, on
a single chip. Hence it became possible to build a complete computer with a
microprocessor, a few additional primary storage chips, and other support circuitry. It
started a new social revolution – the Personal Computer (PC) revolution.
Magnetic core memories were replaced by semiconductor memories , with very fast
access time. Hard disks also became cheaper, smaller in size, and larger in capacity and
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thus became the standard in-built secondary storage device for all types of computer
systems. Floppy disks also became very popular as a portable medium for moving
programs and data from one computer system to another.
The fourth-generation also saw the advent of supercomputers based on parallel vector
processing and symmetric multiprocessing technologies.
Fourth-generation period also saw the spread of high-speed computer networking. LAN
and WAN became popular for connecting computers.
Operating systems like MS-DOS and Windows made their appearance in this
generation. Several new PC-based application packages like word processors ,
spreadsheets and others were developed during this generation. In the area of large-
scale computers, multiprocessing operating systems and concurrent programming
languages were popular technological developments. The UNIX operating system also
became very popular for use on large-scale systems. Some other software technologies
that became popular during the fourth-generation period are C programming language ,
object-oriented software design , and object-oriented programming.
Fifth Generation Electronic computers (1989 – Present)
The fifth Generation was characterized by VLSI technology being replaced by ULSI
( Ultra Large Scale Integration ) technology, with microprocessor chips having ten
million electronic components. ULSI technology is the process of integrating or
embedding millions of transistors on a single silicon microchip.
In fact, the speed of microprocessor and size of main memory and hard disk doubled
almost every eighteen months. The result was that many of the features found in the
CPUs of large mainframe systems of the third and fourth generations became part of the
microprocessor architecture in the fifth generation. More compact and more powerful
computers are being introduced almost every year at more or less the same price or even
cheaper.
The size of main memory and hard disk storage has increased several folds. Memory size
of 256 MB to 4 GB and hard disk sizes of the order of 100 GB are common. RAID
( R edundant Array of Independent Disks ) technology has made it possible to configure a
bunch of disks as a single hard disk with a total size of a few hundred gigabytes. Optical
disks ( CD-ROMS, DVDs ) also emerged as a popular portable mass storage media.
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Summary for generation of computers
Gen Time Circuitry Storage Inputs Output Language OS Speed Example
st
1950s
Vacuum
Tubes
Magnetic
drums
Punched
Cards
Punched
Cards
Machine
Assembly
Operator
controlled
1 Milli
Seconds
-3)
UNIVAC,
ENIAC,
EDVAC
nd
Transistors
Magnetic
tape
Punched
Cards
Punched
Cards
COBOL
FORTRA
N
ALGOL
Batch
Micro
Seconds
IBM 1400 s,
CDC 1604,
Honeywell
rd
IC
Magnetic
disk
Keyboard Monitor
Structured
language
BASIC
PASCAL
Interactive
1 Nano
Seconds
IBM - 360s
Honeywell-
6000 s
ICL 2903,
th
Late
1970s
LSI
VLSI
Mass
Storage
Magnetic
Disks
Mouse,
Scanners,
Sound,
etc.
Monitor,
Printers
Applicatio
n oriented
Language
OOP, C
Virtual
MS-DOS
Windows
UNIX
Nano
Seconds
Desktops,
Laptops,
Tablets
Smartphone
th
Future
ULSI
AI
Optical
disks
Clouds
IOTs
Voice
IRIS
Facial
Voice
Gesture
Facial
JAVA
Python
Distributed
Kernels
1 Pico
Seconds
“Sophia” a
robot.
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1.4. Current/New Trends in Computing
The current or new trends of computing indicates the latest technologies in the domain of
computing and IT.
A shift from the era of mainframe computing and individual computing to a new era of
mobile and smart or green computing
So, apart from the creation and development of computers the types of technology or
concepts that are popular at the current time includes
Cloud computing;
Mobile computing;
Grid computing;
Green computing
Edge Computing
Quantum Computing
Artificial Intelligence
Robotic Process Automation (RPA)
Virtual Reality and Augmented Reality
Internet of Things (IoT)
1.5. Characteristics of computers
The increasing capability of computers has proved that it is a very powerful and useful tool.
Computers have the following characteristics:
Automatic :
o Once a program is in the computer’s memory (once started a job), it carry on until
the job is finished, normally without human intervention.
Speed : Capability of Performing/doing huge amount of tasks within a fraction of
seconds.
o Computer is a very fast device. Units of time are microseconds (
second),
nanosecond (
second) or even picoseconds (
second). A powerful
computer is capable of performing several billions of simple arithmetic operations
per second.
Accuracy:
o The accuracy of a computer is consistently high and the degree of accuracy of a
particular computer depends upon its design. Accuracy of computer mainly
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D. It is electricity dependent.
E. No feeling: computer is devoid of emotion. It has no feelings and no instinct because
it is a machine. It can’t make judgments on its own. Its judgment is based on the
instructions given by the user in the form of programs.
F. Can’t think: even if it is artificially intelligent, it does nothing more than it is
programmed to do nor does it know whether it could do. It does not create a brand
new idea.
G. No IQ. Computer is not a magical device. It cannot do any work without instruction
from the user but it performs the instructions at tremendous speed and with accuracy.
It has to be told what to do and in what sequence.
1.7. Measures of computer quality and performance
The most common things to measure computer performance (Computer performance metrics) or
The most important computer performanc parameters and evalution critrias includes the following
Response Time: the total time lapse between the
completion of an inquiry or demand made on a system
resource and the receipt of a response
Throughput: The computer's throughput is defined as the
number of units of information that can be successfully
processed at any given time.
Latency: Computer latency is defined as the time it
takes to communicate a message, or the time the
message spends traveling the geographical distance ('on
the wire') before it gets to its desired destination
Bandwidth: is a measure of the maximum rate at which
data can be transferred between components of the
computer system, or the amount of data that is sent at any
particular time across a specific connection.
Speed: The term speed is usually in reference to the
clock speed of the processor. The clock speed is
defined as the clock cycles per second, which
determines the rate at which instruction processing
takes place.
Power consumption: The amount of electric power used
by the computer. This becomes especially important for
systems with limited power sources such as solar, batteries,
human power.
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1.8. Types and Classification of computer based on different criteria
Computers can be categorized broadly by their purposes or application, the type of data they
process and their size.
By Application or purpose
o General-purpose computers can be used for different or multiple purposes. We need
only have appropriate software to use a general-purpose computer to perform a
particular task. For example , the personal computers (PCs) currently in wide use are
general-purpose computers.
o Special-purpose computers are specifically designed to perform one particular task.
A computer that guides a missile or whether forecasting is, for example , a special-
purpose computer and Satellite launching is also one example.
By Type of Data or According to the operational principle of computers
o Analog computers process data that vary continuously with time, such as variations
in temperature, speed, chemical composition of petroleum products, or current
flowing through a conductor. Analog computers operate by measuring. They deal
with continuous variable. They do not compute directly with numbers, rather, they
operate by measuring physical magnitude such as pressure, temperature, voltage,
current and etc. Generally, they are computers designed for special purpose. E.g.
Thermometer, voltmeter, speedometer
o Digital computers process digital data. All the PCs currently in wide use are digital
computers. Digital computers deal with discrete variables. They operate by counting
Classification of computers
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corporations, aircraft manufacturer, etc. The CRAY and CYBER are typical
examples of the supercomputers.
o Mainframe computers are mainly found in large organizations. They can serve
hundreds or thousands of users, handling massive amounts of input, output and
storage. They are used as e-commerce servers handling transactions over the
Internet. To give some example, mainframes can handle the processing of thousands
of customer inquiries, employee paychecks, student registrations, sale transactions,
and inventory changes.
o Minicomputers more properly called medium - sized computers; are smaller, slower
and less expensive than mainframes. Minis perform many of the tasks that a
mainframe can, but on a reduced scale. They can support a network of user
terminals, but not as many as mainframes can. They may be used as network servers
and Internet servers. They are popularly used in scientific laboratories, research
centers, universities and colleges, engineering firms, industrial process monitoring
and control. And also they are used for processing data and analyzing results of
experiments.
o Workstations are powerful single-user computers used for tasks that require a great
deal of number-crunching power, such as product design and computer animation.
They are often used as network and Internet servers. Work stations were powerful
sophisticated machines that fit on a desk, cost much and were used mainly by
engineers and scientists for technical purposes. A workstation is like a personal
computer, but it has a more powerful microprocessor and, in general, a higher-quality
monitor.
o Microcomputers, or personal computers, are meant for personal or private
use/ individual use. Microcomputers are small, relatively inexpensive, single-user
( individual user ) computer based on a microprocessor. Microcomputers come in a
variety of sizes and shapes for a variety of purposes. Basically they can be grouped
into three : Laptop , Palmtop and Desktop computers.
Laptop computers are smaller versions of microcomputers about the size of a
briefcase / bags designed for portability. Laptop computers are small enough that it
can sit on your lap. Nowadays, laptop computers are more frequently called
notebook computers.
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Palmtop computer is the smallest microcomputer that is about the same size as a
pocket calculator. Palmtop computer is a portable computer that is small enough to
be held in one’s hand and also called as Hand-held computer , PDAs , and pocket
computers.
Desktop computer is the largest and most widely used type of personal computer
(microcomputers). Desktop computer is a type of microcomputer designed to fit
comfortably on top of a desk , typically with the monitor sitting on top of the
computer.
1.9. Advantages and Disadvantages of computer
Some of the advantages and disadvantages of computer are the followings
In general terms computers can use for the following purposes:-
- To make the work easy
- To do the work efficiently (Efficiency)
- To improve the quality of the result of work (Quality)
- To assist the work (Assistance)
- To finish the task faster (Speed)
1.10. Application areas of computer
Computers have entered in every sphere of human life and found applications in various fields
such as medicine and health care, business, education, science, technology, government,
entertainment, engineering, architecture and agriculture. To this end , we can use computers in an
endless area but to list some of it:
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End of chapter one
