Objective: To acquire the knowledge about the computers and
input and output devices and Operating system Computer
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.
Introduction to Computer
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.
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.
The hardware of
a computer consists of
components and electro
comprises physical entity
of the devices.
components of the
computer are called as
hardware. Example: Hard
disk, floppy disk, mother
board, RAM etc.
The software consists of the
instructions and the data computer
manipulates, to perform various data
The set of programs or
instructions written by the user is called
Example: Tally, Ms-Office, Java, Visual
basic, Oracle etc.
Classification of software:
System software - Ex: MS-DOS
Primary storage concept – secondary
PROM EPROM EEPROM
Floppy disk Hard disk
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
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 – 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.
A commonly used version is the programmable ROM or PROM, which is supplied in blank
form by the manufacturer.
It is possible to erase information stored in an EPROM.
Instead of ROM, many devices now incorporate EEPROM‟s (Electrically Erasable PROM)
which can be easily reprogrammable by the application of a small voltage.
Secondary Storage devices
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 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 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.
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:
Light pads and
Mouse: The mouse used to ‘drive’ Microsoft windows.
The keyboard is still the commonest way of entering information into a computer.
An alternative to the traditional mouse and often used by graphic designers.
A scanner allows you to scan printed material and convert it into a file format that
may be used within the PC.
A device that lays on the desktop and responds to pressure.
Light Pens used to allow users to
point to areas on a screen.
Many games require a joystick for
the proper playing of the game.
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)
A Monitor is other wise called as DVU i.e. Display
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.
A plotter is an output device similar to a printer, but
normally allows you to print larger images.
A Speakers enhances the value of educational and
A speech synthesizer gives you the ability to not only to display text
on a monitor but also to read the text to you.
In large organizations laser printers are most commonly
used due to the fact that they can print very fast and give a very much
There are many different types of printers. There are as follow as below:
Daisy Wheel Printer
Dot Matrix Printer
Laser printers etc.