This document provides an overview of computers, including: 1) A computer manipulates data and can be used for tasks like document writing, emailing, web browsing, spreadsheets, and more. 2) Computers are categorized by their size and use, including supercomputers, mainframes, minicomputers, and microcomputers. 3) Programming languages allow users to communicate with computers and are divided into low-level languages close to machine code and high-level languages resembling English.

1. 1. Introduction to Computers
a. What is a Computer ?
A computer is an electronic device that manipulates information, or data. It has the ability to store, retrieve,
and process data. You can use a computer to type documents, send email, and browse the Web. You can
also use it to handle spreadsheets, accounting, database management, presentations, games, and more.
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2. b. Broad Categories of computer
Computer is divided into three broad categories, and a category has its own categories as given below :
On the basis of Work: Digital, Analog and Hybrid Computer:
SN Digital Computer Analog Computer Hybrid Computer
1 Computer that uses binary
digits to display discreet
information is called digital
computer.
Computer that uses analog signal to
display information is called
Analog computer.
A computer that is able to
understand Binary and
Analog signal to display
information is called
Hybrid computer.
2 Information is in discrete form.
It displays information in
the form of text, graphics,
and pictures.
Information in continuous form and
displayed in the form of curves.
It is used to measure
continuous physical quantity
like as current flow,
temperature, blood pressure,
heart beats.
Information depends on
operating mode of
computer. It can display
information in discrete
and continuous form
because for digital
processing and next part
is for analog processing.
3 Slow Fast Intermediate in Speed
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3. On the basis of Size: Super, Mainframe, Mini and Microcomputer:
Super Computer: Multi-user, multiprocessor large computer of very high efficiency and storing capacity is called
supercomputer able to solve very difficult and complex problem within a nano seconds. A number of RISC
(Reduced Instruction Set Computer) processors are used.
It is used in :
(i) Used to forecast the Weather and global climates
(ii) Used in military research and defense systems
(iii) In automobile, aircraft, and space craft designing
(iv) In encrypting and decoding sensitive intelligence information
(v) Used in seismography, plasma and nuclear research.
(vi) Protein folding analysis
(vii) Study of DNA structure and gene engineering
(viii) Digital film rendering
Example: C-DAC (Center for Development of Advanced Computer) of India has developed PARAM series of Super
Computer.
ANURAG is also Indian Super Computer. Other Super computers are CRAY XMP/14, CDC-205 etc. Mr. Seymour
Cray was a pioneer person in the field of supercomputer production. He had developed the first super
computer Cray-1 in 1976.
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4. Mainframe Computer: It is also very powerful multi-user computer used in large business organizations,
examination department of examinations, industries and defense to process data of complex nature. It can
response several hundred request very quickly. It uses several CPU for data processing.
More than 100 users can use mainframe computer at a time because it works on time sharing mode. IBM built
the first Mainframe Computer, System/ 360, in 1964.
Example: IBM S/390, IBM S/709, ICL 39, CDC 6600
It is used in :
(i)Government and civilian
(ii)Credit card processing
(iii)Bank
(iv)Marketing
(V)Business data processing in large organization
(VI)Air traffic control system
(vii)Industrial design
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5. Minicomputer: Minicomputers are larger and more powerful than most microcomputers but are smaller and
less powerful than most large mainframe computer systems. However, this is not a precise destination. High-
end models of microcomputer systems (super micros) are more powerful than some midrange computers.
It is also multi-user computer and supports more than dozens of people at a time. It is costlier than
microcomputer. It is also used in university, large business organizations to process complex data. It is also used
in scientific research, instrumentation system, engineering analysis, and industrial process monitoring and
control.
Example: PDP-11, VAX etc.
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6. Microcomputer: In 1976 the first personal Computer – Apple-1, Apple computer is designed. In 1981 August,
IBM had announced the IBM 5150 PC, in New York. Now a day mostly used computers are microcomputers. It is
called Home PC or Personal computer (PC) because it is a single user computer. It supports many higher level
languages, multimedia, graphics, 3D graphics and games.
It is popular among students, professionals and home wives due to small size, low price, and low maintenance
cost and easy in operation. The Internet is popular due to PC and it is available for all income groups. The
American weekly magazine regarded it “Machine of year” in 1982 when IBM lunched PC in market first time.
The first IBM PC was equipped with following components:
Intel 8088 Processor of 4.77 MHZ
64 KB RAM (expandable to 256 KB)
40MB ROM
5.25 floppy drive (160KB)″
PC-DOS 1.0 (MS DOS)
Example: IBM PCs, Apple Mac, IBM PS/2 etc.
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7. Laptop and Palmtop Computers
These handheld computers are not replacements for desktop computers. Desktop computers continue to
perform major processing functions, while palmtops are satellite for quick and mobile information access and
communication. Computers are small, portable, less power consuming and equipped with all the facilities of
modern PC. These computers can be operated by battery. These computers have no enough storing capacities
like as desktop computers, but not less in other facilities. It has CD drive, floppy drive, modem and other
input/output ports.
The idea of laptop computer was originated by Alan Kay of Xerox Palo Alto Research Center in 1970 and named
to notebook like computer as Dynabook, but first Laptop was designed in 1979 by William Moggridge of Grid
System Crops. In 1983, Gavilan produced a laptop computer with 64 Kilobyte memory, MS-DOS operating
system, touchpad mouse, portable printer of weight 9Ib.
PALMTOP
Learning and self-improvement are critical to educational leaders. Enormous amounts of information are
created constantly, and the lifelong learner needs to have timely access to it. Web pages and other digital
documents can be put on palmtop computers for enrichment. Palmtop computers are boon for remote area
where there is no electricity facilities available.
The higher authorities, social workers, researcher working in remote rural area get more benefits by palmtop or
laptop computers. The desktop is your personal computer seated at the top of your desk, laptop has no problem
on your lap, and palmtop is happy in your palm.
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8. c. Language of computer
In all over the world, language is the source of communication among human beings. Different
countries/regions have different languages. Similarly, in order to communicate with the computer user also
needs to have a language that should be understood by the computer. For this purpose, different languages
are developed for performing different types of work on the computer. Basically, languages are divided
into two categories according to their interpretation.
1. Low Level Languages.
Low level computer languages are machine codes or close to it. Computer cannot understand instructions given
in high level languages or in English. It can only understand and execute instructions given in the form of
machine language i.e. language of 0 and 1. There are two types of low level languages:
– Machine Language.
– Assembly Language
Machine Language - It is the lowest and most elementary level of Programming language and was the first type
of programming language to be Developed. Machine Language is basically the only language which
computer Can understand. In fact, a manufacturer designs a computer to obey just one Language, its
machine code, which is represented inside the computer by a String of binary digits (bits) 0 and 1. The
symbol 0 stands for the absence of Electric pulse and 1 for the presence of an electric pulse . Since a
computer is Capable of recognizing electric signals, therefore, it understand machine Language.
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9. Assembly Language - It was developed to overcome some of the many inconveniences of machine language.
This is another low level but a very important language in which operation codes and operands are given in the
form of alphanumeric symbols instead of 0’s and l’s. These alphanumeric symbols will be known as mnemonic
codes and can have maximum up to 5 letter combination e.g. ADD for addition, SUB for subtraction,
START,LABEL etc. Because of this feature it is also known as ‘Symbolic Programming Language’. This language is
also very difficult and needs a lot of practice to master it because very small
English support is given to this language. The language mainly helps in compiler orientations. The instructions of
the Assembly language will also be converted to machine codes by language translator to be executed by the
computer.
2. High Level Languages
High level computer languages give formats close to English language and the purpose of developing high level
languages is to enable people to write programs easily and in their own native language environment (English).
High-level languages are basically symbolic languages that use English words and/or mathematical symbols
rather than mnemonic codes. Each instruction in the high level language is translated into many machine
language instructions thus showing one-to-many translation
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10. Types of High Level Languages
Many languages have been developed for achieving different variety of tasks, some are fairly specialized others
are quite general purpose.
These are categorized according to their use as
a) Algebraic Formula-Type Processing. These languages are oriented towards the computational procedures for
solving mathematical and statistical problem
Examples are
BASIC (Beginners All Purpose Symbolic Instruction Code).
FORTRAN (Formula Translation).
PL/I (Programming Language, Version 1).
ALGOL (Algorithmic Language).
APL (A Programming Language).
b) Business Data Processing:
These languages emphasize their capabilities for maintaining data processing procedures and files handling
problems.
Examples are:
COBOL (Common Business Oriented Language).
RPG (Report Program Generator
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11. b) String and List Processing: These are used for string manipulation including search for patterns, inserting and
deleting characters. Examples are:
LISP (List Processing).
Prolog (Program in Logic).
Object Oriented Programming Language
In OOP, the computer program is divided into objects. Examples are:
C++
Java
e) Visual programming language: these are designed for building Windows-based applications Examples are:
Visual Basic
Visual Java
Visual C
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12. e. Components of computer
• Central processing unit (CPU)
A central processing unit (CPU) (formerly also referred to as a central processor unit[1]) is the hardware within
a computer that carries out the instructions of a computer program by performing the basic arithmetical,
logical, and input/output operations of the system.
Two typical components of a CPU are
Arithmetic logic unit (ALU) - Which performs arithmetic and logical operations
Control unit (CU) - Which extracts instructions from memory and decodes and executes them, calling on the
ALU when necessary.
• CPU Speed
– Megahertz (MHz) - the number of millions of CPU cycles per second
– Gigahertz (GHz) - the number of billions of CPU cycles per second
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13. • Input and Output devices
The computer will be of no use unless it is able to communicate with the outside world. Input/Output devices
are required for users to communicate with the computer. In simple terms, input devices bring
information INTO the computer and output devices bring information OUT of a computer system. These
input/output devices are also known as peripherals since they surround the CPU and memory of a
computer system.
• Input devices
An input device is any hardware component that allows you to enter data and instructions onto a computer.
Six Widely used input devices are the keyboard, mouse, microphone, scanner, digital camera and PC video
camera.
• Input device captures information and translates it into a form that can be processed and used by other
parts of your computer.
1. Keyboards
2. Pointing devices
3. Game controllers
4. Scanners
5. Styluses
6. Microphones
7. Digital cameras
8. Web cams
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14. • The keyboard is the most common input device.
Types of keyboards include:
• Wireless
• Multimedia and one-touch access
• Portable keyboards for PDAs
• Pointing Devices
Pointing devices are mainly used to choose and enter commands
Pointing devices tend to have PS/2 connectors or USB connectors
PS/2 connector fits into a PS/2 port, which a small round socket with small holes that fit the pins on the
connector
USB connectors fit into USB ports, and these are small rectangular openings on the back or front of your
computer, or even on your keyboard or monitor
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15. Various pointing devices are available
Types of pointing devices:
1.Mouse
2.Mechanical mouse
3.Optical mouse
4.Wireless mouse
5.Trackball
6.Touchpad
7.Pointing stick
•Game Controllers
Game controllers are used mainly to play games
Types of gaming devices
1.Gamepads
2.Joysticks
3.Gaming wheels
4.Force feed
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16. • Other types of input devices include:
• Scanners
• Styluses
• Microphones
• Digital cameras
• Web cams
Scanners
Scanner is a light sensitive device that helps you copy or capture images, photos, and artwork that exist
on paper. Types of scanners include:
Flatbed
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17. Stylus
Stylus is an input device consisting of a thin stick that uses pressure to enter information or to click and point
Styluses are used with:
•PDAs
•Tablet PCs
•Graphics tablets
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18. Microphones
Microphones are used to input audio
Three main types of microphones are:
•Desktop microphones
•Headsets
•Directional microphones
Digital Cameras
Digital cameras are used to:
•Download images to a computer
•Post pictures to the Web
•Produce videos
•Resolution is measured in megapixels
•Higher the resolution, better the image quality, but the more expensive the camera
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19. Webcam
Web cam is a video camera that can be used to take images for uploading to the Web
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20. Output devices
An output device is any hardware component that conveys information to one or more people. Three
commonly used output devices are a printer, a monitor and speakers.
Output devices take information within your computer and present it to you in a form that you can understand
Main output devices:
•Monitors
•Printers
•Speakers
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21. Monitors
–Cathode-ray tubes (CRTs)
–Flat-panel displays
–Liquid crystal display (LCD) monitors
–Gas plasma displays
Printers
• Inkjet – most popular
–Makes images by forcing droplets through nozzles
–Top speed is 20 pages per minute
• Laser
–Forms images using an electrostatic process
–Prints between 3 and 30 pages per minute
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22.  Multifunction printer:
• Scan, copy, fax, and print
• Can be either inkjet or laser
• Cost less than buying individual units
• Take up less desk space
 Speakers
A speaker is a device that produces computer output as sound
Speakers are common devices in computer systems Examples include:
• Built-in speaker
• Two-device set speakers
• Surround sound speakers
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23. • Computer Memory
In computing, memory refers to the physical devices used to store programs (sequences of instructions) or
data (e.g. program state information) on a temporary or permanent basis for use in a computer or other digital
electronic device. The term primary memory is used for the information in physical systems which function at
high-speed (i.e. RAM), as a distinction from secondary memory, which are physical devices for program and
data storage which are slow to access but offer higher memory capacity.
There are two types of memory
Read only memory
Read only memory (ROM) is the permanent memory which is used to store important control programs and
systems software to perform a variety of functions, such as booting up or starting up programs. ROM is non-
volatile. That means the contents are not lost when the power is switched off. Its contents are written at the
time of manufacture, but in modern (2012) computers may be changed using special software.
Random access memory
Random access memory (RAM) is used as the working memory of a computer system. It stores input data,
intermediate results, programs, and other information temporarily. It can be read and written. It is usually
volatile, that is all data will be lost when the power is turned off. In most cases it is loaded again from hard
disk.
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24. • Concept of hardware and software
Hardware and Software: The Basics
• Hardware – physical aspects of computers, telecommunications, and other information technology
devices
– Example: Keyboard, monitor
• Software -a general term for the various kinds of programs used to operate computers and related
devices
– Example: Microsoft Excel
Six Categories of Hardware
 Input Device
 Output device
 Storage device
 Central processing unit (CPU)
 Telecommunications device
 Connecting device
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25. Two main types of software
• Application software - software used to solve specific problems or perform specific tasks
• System software - handles tasks specific to technology management and coordinates the interaction of all
technology devices
– Operating system software - supports the application software and manages how the hardware devices
work together
– Utility software - provides additional functionality to the operating system
Software contains the instructions that the hardware executes to perform an information processing task
Without the aid of software, the computer hardware is useless
• Two categories of software
– Application
– System
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26. Application Software
• Application software is used for specific information processing needs, including:
– Payroll
– Customer relationship management
– Project management
– Training
– Word processing and many others
• Personal productivity software :
used to perform personal tasks such as writing a memo, creating a graph, or creating a slide presentation
Examples:
– Microsoft Word
– Microsoft Excel
– Internet Explorer
– Quicken
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27. Application Software (Continued)
• Vertical market software :
application software that is unique to a particular industry
– Patient-scheduling software
– Nursing allocation software
• Horizontal market software :
general enough to be suitable for use in a variety of industries
– Inventory management software
– Payroll software
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28. System Software
• System software controls how the various technology tools work together along with the application
software
• Operating System controls application software and manages how the hardware devices work together
– Example: Microsoft Windows XP Home,
Mac OS, Linux
• Utility
– Uninstaller software, spyware software
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29. f. Representation of data concepts and data processing
Definition of Data
Data is distinct pieces of information, usually formatted in a special way. All software is divided into two general
categories: data and programs. Programs are collections of instructions for manipulating data.
Data can exist in a variety of forms -- as numbers or text on pieces of paper, as bits and bytes stored in electronic
memory, or as facts stored in a person's mind.
Strictly speaking, data is the plural of datum, a single piece of information. In practice, however, people use data as
both the singular and plural form of the word.
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30. • Basic data types
In programming, classification of a particular type of information. It is easy for humans to distinguish between different
types of data. We can usually tell at a glance whether a number is a percentage, a time, or an amount of money.
We do this through special symbols -- %, :, and $ -- that indicate the data's type. Similarly, a computer uses special
internal codes to keep track of the different types of data it processes.
Most programming languages require the programmer to declare the data type of every data object, and most
database systems require the user to specify the type of each data field. The available data types vary from one
programming language to another, and from one database application to another, but the following usually exist
in one form or another:
 integer : In more common parlance, whole number; a number that has no fractional part.
 floating-point : A number with a decimal point. For example, 3 is an integer, but 3.5 is a floating-point number.
 character (text ): Readable text
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31. • Storage of data as files
Computer data storage, often called storage or memory, is a technology consisting of computer components
and recording media used to retain digital data. It is a core function and fundamental component of
computers. The central processing unit (CPU) of a computer is what manipulates data by performing
computations.
A modern digital computer represents data using the binary numeral system. Text, numbers, pictures, audio,
and nearly any other form of information can be converted into a string of bits, or binary digits, each of
which has a value of 1 or 0. The most common unit of storage is the byte, equal to 8 bits.
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