2. A Computer System
Hardware
Software
User
Can be divided into generations.
First Generation (1945 – 1954)
Second Generation (1955 – 1964)
Third Generation (1965 – 1974)
Fourth Generation (1975 - )
• Hardware
• Software
• User
Types of Computers
On the basis of Computing Power & Size:
• Laptop / Palmtop
• Micro Computer / Desktop
• Mini Computer / Mainframe
• Super Computer
3. A Computer System
• In general, a computer is a machine which
accepts data, processes it and returns new
information as output.
Data Information
Processing
4. Software
• Software is set of programs (which are step by
step instructions) telling the computer how to
process data.
• Software needs to be installed on a computer,
usually from a CD.
• Softwares can be divided into two groups:
- System SW
- Application SW
5. Software
System Software
• It controls the overall operation of the system.
• It is stored in the computer's memory and
instructs the computer to load, store, and
execute an application.
• Examples: Operating System (OS), Translators
DOS, Windows, Unix etc.
6. Software
Application Software
• They are Softwares written to perform specific
tasks.
• The basic types of application software are:
word processing, database, spreadsheet,
desktop publishing, and communication.
Examples: MSOffice, Tally
7. Advantages of Using Computers
• Speed: Computers can carry out instructions in less
than a millionth of a second.
• Accuracy : Computers can do the calculations without
errors and very accurately.
• Diligence : Computers are capable of performing any
task given to them repetitively.
• Storage Capacity : Computers can store large
volume of data and information on magnetic media.
8. Language of Computers
• Computers only understand the electronic
signals.
Either Current is flowing or not.
• Current Flowing : ON
• Current Not Flowing : OFF
• Binary Language
• ON : 1
• OFF : 0
• Bit, Byte, KB, MB, GB,TB
9. Computer Network
• A Computer Network is interconnection of
Computers to share resources.
• Resources can be : Information, Load, Devices etc
Types Of Computer Networks
On the basis of Size:
• Local Area Network (LAN)
Its a network of the computers locally i.e. in one room, one
building.
• Wide Area Network (WAN)
Its a network of the computers spread widely
geographically.
10. Benefits of Computer Networks
• Information Sharing
• Device Sharing
• Load Sharing
• Mobility
• Fast
Communication
• Anywhere Anytime
Banking
Internet
• Internet is a huge network
of computer networks.
• Internet provides many
services:
– Email
– World Wide Web
(www)
– Remote Login (Telnet)
– File Transfer (FTP)
11. CPU
• The central processing unit or (CPU) is the "brain"
of your computer. It contains the electronic circuits
that cause the computer to follow instructions
from memory.
• The CPU contains three main parts, all housed
in a single package (Chip):
–Control Unit (CU)
–Arithmetic Logic Unit (ALU)
–Memory
12. What these components do.
• Power Supply – (heart) supplies power to all the circuitry and
devices.
• Motherboard – (body) acts as a manager for everything on the
computer – connects all the other components together.
• CPU – Central Processing Unit – (brain) this does all the work
of computing.
• RAM – Random Access Memory – (short-term memory) holds
data and program instructions that the computer is currently
using.
• Hard Drive – (long-term memory) holds all of the information
that needs to be stored between uses of the computer.
13. What these components do…
• Floppy and CD-ROM drives – (mouth/ears) allow you to give data to the
computer and take data away from the computer.
• Card Slots – (fingers) Allows other components to be added
to the computer.
• Video card – (face) Does all of the processing necessary to
get stuff looking nice on screen, quickly.
• Sound card – (vocal cords) Allows sounds from HD or CD-
ROM to be played.
• Network Card – (telephone) allows computer to talk to other
computers over a wire.
14. Inside The CPU Cabinet
•The central processing unit (CPU), also known as "processor”,
is the "brain" of your computer.
• It contains various electronic circuits.
Examples: Intel Family – Pentium 4, 3, 2, Pentium,
XEON, Itanium
AMD -- Athlon, K62
IBM -- Cyrix
Motorola -- 68000 SeriesCU
ALU
Memory
Registers
21. Keyboard
• The keyboard looks like a typewriter.
• It operates like a typewriter keypad, but instead of
moving an arm, which strikes the paper, it sends
an electronic impulse to the computer, which
displays a character on the monitor.
• Keypad contains: Alphabets, Numbers, Special
Symbols, Function Keys
• qwert Keyboard (Typewriter Keyboard).
• On key press it sends a code (ASCII Code) to the CPU
22. • Its a device that is used to control the computer. A cable
connects the mouse to the computer.
• When the mouse is moved on a pad, called a mouse pad,
the cursor on the screen moves. Wheel / Optical Mouse
• A cursor is a small symbol displayed on the computer
screen (normally a diagonal arrow that is used as a pointer)
that shows you what the mouse is referencing on the
screen.
• Pointing & Click Device, Two / Three Buttons
• Normally Left Click – Select/ Run
Right Click – Popup Menu
Mouse
23. VDU (Monitor)
• This is the television-like screen where the results
of a computer's tasks are displayed.
• Monitors come in all sizes, but most commonly
they are either 15 or 17 inches
(measured diagonally from one corner of the
screen to the opposite corner).
24. Hard Disk
• Magnetic Memory Device.
• Non-removable storage device.
• Several Circular Magnetic Disks are housed in a
single case.
• Data is stored as 1s & 0s.
• Typical Capacity is 20 GB -80 GB
• Cost/Bit is Low.
25. Floppy Disk
• Magnetic Memory Device, Removable storage.
• A single circular plastic disk, coated with magnetic
material is packed in a protective plastic casing.
• Typical size is 3.5” & Capacity is 1.44MB
CD ROM
• Optical Device, Removable Storage.
• Read Only Memory.
• Typical Capacity is 550 Mb – 800MB
• Related Terms: CD Writer, WORM, CD RW
26. Printer
• Output Device, Produces Hard Copy
• Types:
– Dot Matrix
– Inkjet
– Laser
• Related Terms: Impact – Non Impact
– Ribbon, Cartridge, Toner, Duty Cycle
• Major Vendors in India:
– HP, Cannon, Samsung, TVS, Epson etc.
– A printer is designed to output information from a
computer onto a piece of paper.
27. Scanner
• Input Device, Converts a hard copy into a
computer file.
• Used to Scan Signatures, Photographs etc.
• Optical Device.
• Major Vendors in India: HP, Umax, Cannon
• Nowadays Scanners with OCR produces
editable documents.
28. What is Operating System
OS is system software, which may be viewed as
collection of software consisting of procedures for
operating the computer.
It provides an environment for execution of programs
(application software).
It’s an interface between user & computer.
29. Computer Machine
(Hardware)
User / Programmer
Operating System
Human Understandable Language
(High Level Language)
Machine Language
(Low Level Language)
30. Types of OS
Multiprogramming OS
Multitasking/Multiprocessing
Multiuser OS
Time Sharing OS
Real Time OS
Distributed OS
Functions of OS
File Management
Memory
Management
Process Management
Device Management
31. A Second Classification
This Classification is based on the type of interface
Operating System provides for the user to work in.
Character User Interface (CUI)
The User has to type the commands on the command prompt
to get the work completed.
Ex. DOS, UNIX.
Graphical User Interface (GUI)
The User need not type any commands. He/ She just point and
clicks on the desired Icon to get the work done.
Ex. Windows (9X, XP, NT, 2000), Linux.
32. Types of Processing
Serial Processing
The job is processed at the time when
it is submitted.
Batch Processing
The similar jobs are bunched together and
are kept for processing at an later time.
33. Overview of Windows
Windows is an GUI based operating system.
It is also developed by Microsoft Corporation, which is headed by
Mr. Bill Gates.
Over the years the Microsoft have evolved various versions of
Windows. Win95, Win98, Win2000, Win ME, Win NT, Win XP.
It gives user a handy environment where he doesn’t have to
remember and learn the syntaxes of various commands as is the case
in DOS.
The user can just point and click on the Icons provided to him on the
screen.
34. Folders and Documents
Folders are a way to organize your documents within drives in Windows as
are the directories in DOS.
A document is each thing that you create on a computer. A document can
be made using any type of software.
