1. Unit-1
Objective: To acquire the knowledge about the computers and
input and output devices and Operating system Computer
concepts
Introduction to computers – Definition – Advantages &
dis-advantages – classification of computers
(Desktop, Laptop, Notepad) – hardware features & uses –
Defining hardware – components of computer – block diagram
of computer – Primary storage concept – secondary storage
devices – input/output Devices – Software concepts -
Operating System (O/S) – MS DOS, Windows –
2000/Xp, Unix) Language classification ( Higher
level, lower level, Assembly) – Compiler and interpreter.

2. Introduction to Computer
Introduction
The word Computer comes from the word “Compute”
which means “Calculate”. So a Computer normally as a
calculating device considered. Then can Perform Arithmetic
operations enormous speed.
Meaning
1. Computer is an electronic device. Computer is a
designed to automatically accept and store input data
manipulates them and produces out put through step-by-step
instructions which is stored in a program. Thus a
programmable machine is called computer.
2. Computer is an Electronic device.

3. Fundamental Entities of a
computer

4. Hardware
Meaning :
The hardware of
a computer consists of
the electronic
components and electro
mechanical that
comprises physical entity
of the devices.
The physical
components of the
computer are called as
hardware. Example: Hard
disk, floppy disk, mother
board, RAM etc.

5. Software
Meaning:
The software consists of the
instructions and the data computer
manipulates, to perform various data
processing tasks.
The set of programs or
instructions written by the user is called
as software.
Example: Tally, Ms-Office, Java, Visual
basic, Oracle etc.
Classification of software:
System software - Ex: MS-DOS
Application software
Utility software

7. Primary storage concept – secondary
storage devices
STORAGE
DEVICES
Primary
Storage device
RAM ROM
PROM EPROM EEPROM
Secondary
Storage Device
Floppy disk Hard disk

8. Primary Storage
Meaning :
Primary storage is usually referred to Random Access Memory (RAM), because it is
possible to randomly select and use any location of this memory to directly store and retrieve data and
instructions.
RAM
RAM – Random Access Memory
It is also referred to as read/write memory because information can be „read‟ from RAM chip and can
also be „written‟ into it.
ROM
ROM – Read Only Memory is one in which information in permanently stored. The
information from the memory can only be read and it is not possible to write fresh information into it.
PROM
A commonly used version is the programmable ROM or PROM, which is supplied in blank
form by the manufacturer.
EPROM
It is possible to erase information stored in an EPROM.
EEROM:
Instead of ROM, many devices now incorporate EEPROM‟s (Electrically Erasable PROM)
which can be easily reprogrammable by the application of a small voltage.

9. Secondary Storage devices
Meaning:
Secondary storage large volume of data on a permanent basis which can be partially transferred
to the primary storage as and when required for processing. It is commonly used for “backing up data”.
Floppy Disk:
“Floppy” disk drives allow you to save work on small disks and take the data with you.
Speed : Very slow.
Capacity : Normally 1.44 Mbytes.
Cost : Very cheap.
Hard disk
Hard disk drives are an internal, higher capacity drive which also stores the operating system
which also stores the operating system which runs when your power on the computer.
Speed : very fast
the speed of a hard disk is often quoted as “average access time” speed, measured in milliseconds. The
smaller this number the faster the disk.
Capacity : Enormous Often 40/80 Gigabytes. A Gigabyte is equivalent to 1024 Megabytes.
Cost : Hard disks costs are falling rapidly and normally represent the cheapest way of storing data.

10. Input Devices
Input device is any machine that feeds data into
computer. For example a keyboard is an input device, whereas
a display monitor is an output device. A keyboard and mouse
are the standard way to interact with the computer.
There are as follow as below:
Mouse
Keyboard
Tracker balls
Scanners
Touch pads
Light pads and
Joy sticks
Input/output Devices

11. Mouse: The mouse used to ‘drive’ Microsoft windows.
Keyboard :
The keyboard is still the commonest way of entering information into a computer.
Tracker balls:
An alternative to the traditional mouse and often used by graphic designers.
Scanners
A scanner allows you to scan printed material and convert it into a file format that
may be used within the PC.
Touch pads:
A device that lays on the desktop and responds to pressure.

12. Light Pens
Light Pens used to allow users to
point to areas on a screen.
Joysticks
Many games require a joystick for
the proper playing of the game.

13. Meaning:
Output is anything that comes out of a computer. Output can
be meaningful information and it can appear in a variety of forms – as a
binary numbers, as pictures and as printed pages.
The monitor (the screen) is how the computer sends
information back to us. A printer is also an output device.
There are as follow as below:
Monitor or DVU (Display Visual Unit)
Plotters
Speakers
Speech
Speech synthesizers
Printers
OUTPUT DEVICES

14. Monitor:
A Monitor is other wise called as DVU i.e. Display
Visual Unit.
Monitor is another term for the display screen. The
screen is closely linked with the keyboard so that whatever
characters are typed will be displayed.
Plotters
A plotter is an output device similar to a printer, but
normally allows you to print larger images.
Speakers
A Speakers enhances the value of educational and
presentation products.

15. Speech synthesizers
A speech synthesizer gives you the ability to not only to display text
on a monitor but also to read the text to you.
Printers
In large organizations laser printers are most commonly
used due to the fact that they can print very fast and give a very much
quality output.
There are many different types of printers. There are as follow as below:
Character Printers
Daisy Wheel Printer
Line Printer
Dot Matrix Printer
Inkjet Printer
Laser printers etc.

16. INPUT & OUTPUT DEVICES