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What is a Computer?
An electronic device that stores, retrieves,
and processes data, and can be
programmed with instructions. A
computer is composed of hardware and
software, and can exist in a variety of
sizes and configurations.
Hardware & Software
The term hardware refers to the physical
components of your computer such as the
system unit, mouse, keyboard, monitor etc.
The software is the instructions that makes
the computer work. Software is held either
on your computers hard disk, CD-ROM,
DVD or on a diskette (floppy disk) and is
loaded (i.e. copied) from the disk into the
computers RAM (Random Access Memory),
as and when required.
Types of Computers
Mini and Mainframe Computers
Very powerful, used by large
organisations such an banks to control
the entire business operation. Very
expensive!
Personal Computers
Cheap and easy to use. Often used as
stand-alone computers or in a network.
May be connected to large mainframe
computers within big companies.
Hardware Components
Input Devices --
"How to tell it what to do“
- A keyboard and mouse are the standard way to
interact with the computer. Other devices include
joysticks and game pads used primarily for games.
Output Devices -- "How it shows you what it is doing"
- The monitor (the screen) is how the computer
sends information back to you. A printer is also an
output device.
Hardware Components
INPUT DEVICES
The Mouse
Used to ‘drive’ Microsoft Windows
The 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
INPUT DEVICES
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
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
OUTPUT DEVICES
VDU
The computer screen is used for outputting
information in an understandable format
Printers
There are many different types of printers.
In large organizations laser printers are
most commonly used due to the fact that
they can print very fast and give a very
high quality output.
OUTPUT DEVICES
Plotters
A plotter is an output device similar to a
printer, but normally allows you to print
larger images.
Speakers
Enhances the value of educational and
presentation products.
Speech synthesisers
Gives you the ability to not only to display
text on a monitor but also to read the text
to you
Storage Devices -- "How it saves data and
programs“
- Hard disk drives are an internal,
higher capacity drive which also stores the
operating system which runs when you power
on the computer.
- "Floppy" disk drives allow you to save
work on small disks and take the data with
you.
Hard Disks
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.