1. THE COMPUTER
A computer system is the synthesis of
hardware and software. A typical
computer system employs a computer
that uses programmable devices to store,
retrieve, and process data.

2. The personal computer or PC exemplifies
one example of a computer system. An
Automatic Teller Machine (ATM) is another
example of a computer system.
The Internet does NOT exemplify a
computer system per se, but rather a
network of computer networks.

3. 1. Hardware
•Computer hardware is the physical part of a computer,
including the digital circuitry, as distinguished from the
computer software that executes within the hardware.
•The hardware of a computer is infrequently changed, in
comparison with software and data, which are "soft" in
the sense that they are readily created, modified or
erased on the computer. Firmware
• is a special type of software that rarely, if ever, needs to
be changed and so is stored on hardware devices such as
read-only memory (ROM) where it is not readily changed
(and is therefore "firm" rather than just "soft").

4. 2. Uses
•Personal computers are normally operated by
one user at a time to perform such general
purpose tasks as word processing, internet
browsing, e-mail and other digital messaging,
multimedia playback, video game play,
computer programming, etc.

5. 3. Categories of Personal computers as to
size and portability:
a. Desktop Computer
This is an independent personal computer that is
made especially for use on a desk in an office or s
used mainly to distinguish this type of personal
computer from portable computers and laptops, but
also to distinguish other types of computers like the
PDA, server or mainframe.

6. All-in-one
• All-in-one computers are desktop computers that
combine the monitor into the same case as the CPU.
•The term, "all-in-one" was initially associated with
Digital Equipment Corporation's VAX "all-in-one"
software which provided a common menu to
choose: email, spreadsheet, database, file system,
etc

7. b. Laptop
A laptop computer or simply laptop (also
notebook computer or notebook) is a small
mobile personal computer, usually weighing
from one to three kilograms, depending on
size, materials and other factors.

8. .Personal Digital Assistant
Personal digital assistants (usually abbreviated to PDAs) are
handheld devices that were originally designed as personal
organizers, but became much more versatile over the years.
A basic PDA usually includes date book, address book, task
list, memo pad, clock, and calculator software. Newer PDAs
also have both color screens and audio capabilities, enabling
them to be used as mobile phones (PDA Phone), web
browsers or media players. Many PDAs can access the
Internet, intranets or extranets via Wi-Fi, or Wireless Wide-
Area Networks (WWANs).

9. d. Portable Computer
A Portable computer is a computer that is designed
to be moved from one place to another (in other words,
it is a computer that is portable). Portable computers,
by their nature, are microcomputers.
Early portables were unkindly referred to as
"luggables," referring to their great size and weight
(owing partly to the need to include a full-blown CRT
monitor, as LCD technology was not yet mature).

10. e. Tablet PC
A tablet PC is a notebook- or slate-shaped mobile
computer.
Its touch screen or digitizing tablet technology allows the
user to operate the computer with a stylus or digital pen
instead of a keyboard or mouse.
A user can input text using the built-in handwriting
recognition, on-screen (virtual) keyboard, speech
recognition, or a physical

11. f. Wearable computer
A wearable computer is a small portable computer
that is designed to be worn on the body during use.
In this wearable computers differ from PDAs, which
are designed for hand-held use, although the
distinction can sometimes be a blurry one.

12. Wearable computers are usually either
integrated into the user's clothing or can be
attached to the body through some other
means, like a wristband.
They may also be integrated into everyday
objects that are constantly worn on the
body, like a wrist watch or a hands-free cell
phone.

13. 4. Software
The software is the information that the
computer uses to get the job done.
Software needs to be accessed before it can be
used. There are many terms used for process of
accessing software including running,
executing, starting up, opening, and others.

14. The three basic types of software are:
commercial, shareware and open source
software.
Some software are also released into the
public domain without a license.

15. •Commercial software comes
prepackaged and is available
from software stores and
through the Internet.

16. • Shareware
is software developed by individual and small
companies that cannot afford to market their
software world wide or by a company that wants to
release a demonstration version of their commercial
product.
You will have an evaluation period in which you can
decide whether to purchase the product or not.
Shareware software often is disabled in some way
and has a notice attached to explain the legal
requirements for using the product.

17. •Open Source software
is created by generous programmers and released into the
public domain for public use. There is usually a copyright
notice that must remain with the software product.
Open Source software is not public domain in that the
company or individual that develops the software retains
ownership of the program but the software can be used
freely.
Many popular Open Source applications are being
developed and upgraded regularly by individuals and
companies that believe in the Open Source concept.

18. Types of Memory
RAM - random access memory, also known as
Read-Write memory, can have new data written
into it as well as stored data read from it. A
drawback of RAM is that it requires electrical
power to maintain data storage. If the computer
is turned off or looses power, all data stored in
RAM is lost, unless if the data was saved to disk
ROM - read-only memory, computer memory on
which data has been prerecorded; once data has
been written onto a ROM chip, it cannot be
removed and can only be read

19. 5. Disk and Storage
Disks are used to store information.
Information on computers are stored
in files. The size of a file is measured in
bytes.

20. A byte is approximately one character (letter 'a',
number '1', symbol '?' etc....).
•About a thousand bytes is a kilobyte (KB).
•About a million bytes is a megabyte (MB).
•About a billion bytes is a gigabyte (GB).

21. A byte is made up of 8 bits. A bit is simply an
on or an off signal which passes through the
computers circuitry. Every piece of software
can be broken down into a series of on or off
signals or its Binary Code.
•Floppy disks are still a common way of
transporting information (such as bringing files
home from work) but compact disks (CDs) and
Digital Video Devices (DVDs) are becoming
more popular. Most software are sold on CDs.
• Hard disks are the most common storage
device.

22. Basic Computer Operations
How Computers Work
Input: Information and programs are entered
into the computer through Input devices such as
the keyboard, disks, or through other computers
via network connections or modems connected
to the Internet. The input device also retrieves
information off disks.

23. Output: Output Devices displays
information on the screen (monitor) or the
printer and sends information to other
computers. They also display messages
about what errors may have occurred and
brings up message or dialog box asking for
more information to be input. The output
device also saves information on the disk
for future use.

24. Processing: The CPU or central processing unit
is sometimes called the Control Unit and directs
the operation of the input and output devices.
he Coprocessor or the Arithmetic-Logic Unit
does arithmetic and comparisons. The memory
or RAM temporarily stores information (files
and programs) while you are using or working
on them. The BIOS or basic input/output
system controls the dialogue between the
various devices.