1. BASIC CONCEPTS OF A COMPUTER
Computer: A computer may be defined as a device, which operates upon data
which comes in various shapes and sizes, depending upon the type of computer
application.
Elements of Computer:
i) Hardware: Physical or tangible components of computer i.e., those that can
be touched are hardware. Main hardware components include input, output,
memory devices etc.
ii) Software: Intangible components of a computer i.e those parts that can be
touched are software’s. Main software components include operating system,
application programs etc.
iii) Firmware: It is a combination of software and hardware. It includes
computer chips that have data or programs recorded on them.
iv) Data: It is a collection of characters, numbers, images etc that can be
processed by computer.
v) Procedure: It is the activity of manipulating data by computer to produce
information.
Characteristics of Computer:
i) Automatic: A computer is said to be automatic, if it works by itself without
human intervention. Computers are automatic machines because once started on
a job, they carry on until the job is finished without human assistants.
ii) Speed: A computer is a very fast device, it can perform billions of operations
per second.
iii) Accuracy: The accuracy of a computer is consistently high, and the degree
of accuracy of a particular computer depends upon its design.
iv) Diligence: Unlike human beings, a computer is free from monotony,
tiredness and lack of concentration. It can continuously work for longer hours.
v) Storage: A Computer can store and recall huge amount of information
because of its secondary storage.
2. vi) Versatility: A computer is capable of performing many tasks at the same
time without confusion. Suppose, one moment it is busy with preparing
electricity bills, next moment it is busy with preparing office files etc.
History of Computers/ Generations of Computer:
The generation of computer is divided into
i) First Generation
ii) Second Generation
iii) Third Generation
iv) Fourth generation
v) Fifth generation
i) First Generation Computers:
These computers were made up of vacuum tubes.
ENIAC (Electronic Numerical Integrator and Calculator) was the first
general purpose electronic-digital computer designed by John Nauchly
and John Presper Eckert.
ENIAC was decimal rather than binary machine.
ENIAC was weighted 30 tons, occupied 15000 feet of floor space,
contained 18000 vacuum tubes and consumed large amount of (140kw)
electricity.
ii) Second Generation Computers:
These computers were made up of Solid-State Device known as
transistors.
The transistor was invented at Bell laboratories in 1947 and by late 1950s
and it was made up of silicon.
Some examples of this generation are PDP-I from Digital Electronic
Corporation.
iii) Third Generation Computers:
This computers were made up of Integrated Circuits(IC), in specific SSI
and MSI technology used.
3. The third generation saw the advent of transistors and IC boards which is
technically termed as micro-electronic age, which produces digital
circuits and consistent trend towards reduction in computer size.
iv) Fourth Generation Computers:
These computers were made up of micro processor (as thousands of
integrated circuits were built onto a single silicon chip).
As these small computers become more powerful, they could be linked
together to form networks, which eventually led to the development of
internet, and also saw the development of GUI’s , the mouse, handheld
devices etc.
v) Fifth Generation Computers:
These computers made up of artificial intelligence such as voice
recognition etc.
The use of parallel processing and super conductors is helping to make
artificial intelligence a reality.
The goal of fifth generation computing is to develop devices that respond
to natural language input.
Classification of Computers
i) Technical classification
ii) Commercial Classification
i) Technical Classification:
a) Analog Computers:
It gives data output in the form of voltage.
It is made up of electronic components like registers, capacitors, DC
amplifiers etc.
It is used in scientific and engineering fields.
It is less accurate compared to digital computers.
b) Digital Computers:
It gives the data output in the form of binary language like 0 and 1.
4. It is made up of logic circuits.
It is used in general computing, automobiles, aeroplanes, radar controllers
etc.
It is better in terms of accuracy compared to analog computers.
c) Hybrid computers:
These computers are combining the features of both analog and digital
computers.
ii) Commercial Classification:
a) Super computers:
Most powerful, extremely fast and most expensive computers.
They have multiple microprocessors, all of which functions in
parallel.
These computers use in weather forecasting, automobile designing,
satellite launching etc.
Eg: PARAM from C-DAC
b)Workstation computers:
These are powerful single user computers used by engineers,
scientists, graphic artists etc.
Use in scientific research, network and internet servers.
Eg: Personal computers
c) Mainframe computers:
Which generally have many terminals or PCs connected to them, it
can handle massive amounts of input, output and storage.
It is less powerful than super computers.
These are used in wide area networks, railway reservations,
banking sector etc.
Eg: IBM 3000 series
d)Mini computers:
5. These are designed to support multiple users and high speed
peripheral devices.
These are suitable for medium to large organisations having high
volume processing requirements.
Use in payroll processing and financial accounts, production
planning, use like server in LAN etc.
Eg: Digital Equipments PDP 11/45.
e) Micro computers:
In these computers, the ALU and the CU are combined and
housed in a small IC chip called the microprocessor.
Micro computers are also known as personal computers.
Use in word processing, managing database, Personal accounting
etc
It classified as Desktop, Laptops, Notebooks,
Palmtops etc.
Eg: IBM PC, APPLE etc.
BASIC COMPUTER ARCHITECTURE
The main functional units of a computer are
i) Input unit
ii) Output unit
iii)Memory unit
iv) Central processing unit(CPU)
6. i) Input Unit:
It links external environment with the computer system by allowing data and
instructions to enter the computer system before any computations can be
performed.
The various input devices are keyboard, mouse, scanner etc.
ii) Output devices:
The output unit supplies information and results of computation to the outside
world.
The various output devices are monitor, printer etc.
iii) Memory unit:
It is designed to store data and instructions that are entered into the computer
system through input unit before the actual processing starts. It also stores the
intermediate results produced by the computer for ongoing processing and also
stored the results produced by the computer after processing data and
instructions.
7. The storage devices include CD drives, pen drives etc.
iv) Central Processing Unit:
The processor (CPU) is the brain of any computer system.
All major calculations and comparisons performed by a computer are
carried out inside its CPU.
The CPU is also responsible for activating and controlling the operation
of other units of the computer system.
