2. Types of computers
The desktop (tower, monitor, keyboards,
mouse)
The laptop (advance of portability)
The palmtop (smallest and lightest)
3. Computer systems
Process is undertaken in central processing
unit or CPU.
Secondary storage: computer hard disk or
CD-ROM.
Primary storage or memory
4. How a computer works:
First you have to tell the CPU what you want it
to do: choose the program:
Typing Keyboard CPU
Secondary
Storage
(programs and data)
signal Monitorsignal Image
on screen
6. Input devices
Scanners:
Image scanners (similar to photocopiers by
taking a picture of the input document)
Optical character recognition scanners
(capable of recognizing more fonts).
Bar code readers
7. Input devices
Scanners:
Magnetic strip readers (Automatic Teller
Machines)
Optical Mark Recognition (shown as marks in
particular places on a document)
9. The Central Processing
Unit
The CPU is the heart of the computer.
Two aspects are important:
Type of processor and speed (ability to
undertake sophisticated applications)
Main memory (RAM random access
memory, (ROM) read only memory)
10. Output devices
Screens output device known as visual display
units (VDUs) with a variety of sizes such as
14”-21”
11. Output devices
Printers:
Serial printers: print one character at a
time.
Inkjet printers: spray painting each
character onto the paper.
Dot matrix printers: same way as a
typewriter and they are capable of
producing a number of different fonts.
12. Output devices
Printers:
Line printers: memorize a line at a time and
printing that line by character.
Page printers or laser printers: they produce
high quality output, also in colour and their
cost is over £500.
13. Output devices
Voice output (speech is after all organized in
a particular way).
Other types of output (microfilm, video
sound, information printed in miniature form
etc).
14. Storage
Memory:
(i) random access memory
(ii) read only memory
Memory is measured in “bytes”:
1 byte is a grouping of 8bits which the
computer can operate on a single unit.
16. DATA and FILES
The combination of data in a whole package is
package called a “file”.
The name consists in two parts: a filename and
an extension. Thus a file could be known as
“MYFILE.DOC”.
17. Secondary Storage
Classified in two different ways:
(i) A permanent part of the computer’s internal
structure (hard disk) or a external object.
(ii) The medium storage -tape, disks or
memory disks.
18. Secondary Storage
Storage devices:
(i) Magnetic tape (the oldest form of storage
device).
(ii) Data files are stored also on disks.
(iii) A computer’s hard disk is usually the main
secondary storage facility.
(iv) CD-ROM disks with capacities up to 4 Gb
(v) DVDs (digital versatile disks) which can store up
to 16G
(vi) Memory sticks: very small devices with large
memories
19. Software
The programs which instruct the computer to do
things.
(i) System software:
The most important part of such software is the
operating system - an integrated set of
programs which manage CPU operation,
control input, output and storage activities and
devices.(windows, ms-dos, Linux etc)
20. Applications - Software
Dedicated programs are those for particular business
purposes such as payroll, accounting, auditing etc.
General -purpose programs are for common information -
processing activity:
Word processing (printing, writing, editing documents, text
data)
Spreadsheets -manipulation of mathematical figures of
decision support systems
21. Applications - Software
Databases - allow the storage and retrieval of data and
records and their manipulation.
Graphics - cover graphic presentation of numerical data and
the creation, editing and printing of images for
presentation purposes.
22. TECHNOLOGY AND COMMUNICATIONS
COMPUTER COMMUNICATION
Need to transfer data from one
computer to the other
Need for terminals to be located far
from the main computer.
23. TECHNOLOGY AND COMMUNICATIONS
Networks –two ways of computer s which are
connected to each other and are able to
exchange data:
In the form of wheel, (one central computer
and a number of satellite computers)
24. TECHNOLOGY AND COMMUNICATIONS
Networks –two ways of computer s which are
connected to each other and are able to
exchange data:
In the form of a circle, (computers are
linked together and data can be easily
exchanged between all of them).
25. Local area Networks (LANs)
LANs link together over small distances,
usually in the same building.
A device which provides a service to other
computers on the network is known as a
“server” (printer server).
A
B
PRINTER
DC
E
26. TECHNOLOGY AND COMMUNICATIONS
WIDE AREA NETWORKS (WANs)
A wide area network (WAN) is a
telecommunication network that covers a
broad area (i.e., any network that links
across metropolitan, regional, or national
boundaries).
27. TECHNOLOGY AND COMMUNICATIONS
INTERNET:
is a global system of interconnected
computer networks that use the standard
Internet Protocol Suite (TCP/IP) to serve
billions of users worldwide.
42. TECHNOLOGY AND COMMUNICATIONS
E – commerce
refers to the buying and selling of
products or services over
electronic systems such as the
Internet and other
computer networks.
