2.  A computer system is defined as
combination of components designed to
process data and store files. A
computer system consists of four major
hardware components; input devices,
output devices, processor and storage
devices. A computer system requires
hardware, software and a user to fully
function.

3. • Input is any data or instructions that we enter into the computer system for processing. There
are four types of input: which are text, graphic, audio and video. Example of input devices are
keyboard, light pen, joystick, microphone, mouse, video & digital camera.
input
• The processing unit controls all activities within the system. The CPU is an example of a
processor. It has the same important as the brain to human being.
process
• Storage is a location which data, instruction and information are held for future use. It
is the physical material that keeps keeps data, instruction and information. There are
two types of storage. They are the primary storage and secondary storage. The example
Storage of storage devices are hardisk, Floppy Disk, diskette, RAM, CD ROM and DVD ROM.
• Output is data that has been processed into a useful form, called information. There
are four types of output, which are texts, graphics, audio and video. Example of output
devices are monitor, printer, speaker and plotter.
output

4. input process storage
•Users input data or instruction •Data or instruction being input •Computer storage is important to
into the computer system to be into the computer system is then help users store programs and data
process. Input could be either processed by the CPU which to be used at a later time.
text, graphic, audio or video. controls all activities within the •It is also useful to keep current
Input devices are used by users to system. The results of the data while being processed by the
input data. Input devices are any processed data are then sent to an processor until the information is
electronic device connected to a output device as usable data. saved in a storage media such as a
computer and produces input •A CPU interprets the and carries hard disk or a diskette. Computer
signals. out the instructions by processing storage also stores instructions
data and controlling the rest of from a computer program. There
the computer’s components. are two type of computer storage;
•A CPU consists of two primary storage and secondary
subcomponents; the Control Unit storage.
(CU) and the Arithmetic Logic
Unit (ALU). CU’s main function is
to direct the CPU to process data
by extracting instructions from
memory and decodes and executes
them. The CU manages a four-step
basic operation which is called a
machine cycle. The steps are
Fetching, Decoding, Executing &
Storing

5. Binary
digit
Character
Bit
codes
Character Byte

6. BINARY DIGIT
 Computers recognize only two discrete states: on and off. These states can be
represented by two digits, 0 and 1. Each 0 or 1 is called a bit in the binary system.
 Bit is the smallest unit of data a computer can process. Bit is a short for binary digit.
The binary system has a base of 2 with the two digits (0 and 1). Combinations of 0s and 1s
represent larger numbers.
BIT
 A bit is the smallest unit of data that the computer can process. Bit is a short for binary
digit. A bit is represented by the numbers 1 and 0. These numbers represent the binary
system. They correspond to the states of on and off, true and false, or yes and no.
 All digital data use the binary system to process the information. This information
include letters, digits or special character.
BYTE
 Byte is a unit of information built from bits. One byte is equals to 8 bits. Eight bits
that are grouped together as a unit. A byte provides enough different
combinations of 0s and 1s to represent 256 individual characters.
 One byte represents a single character such as the number 3, letter b or a $
symbol. Bits and bytes are the basis for representing all meaningful information and
programs on computers.

7. CHARACTER
 8 bits = 1 byte
 One byte represents one character such as A, 7, 9 and +.Eight bits that are grouped
together as a unit. A byte provides enough different combinations of 0s and 1s to
represent 256 individual characters.
 For example, the capital letter F is represented by the binary code 01000110 that can
be understood by the computer system. Eight bits grouped together as a unit are
called a byte. A byte represents a single character in the computer.
CHARACTER CODES
 There are three character codes to represent characters which are ASCII, EBCDIC
and Unicode. Each byte contains eight bits. A byte provides enough different
combination of 0s and 1s to represent 256 characters.
 The combinations of 0s and 1s are defined by patterns. These patterns are called
coding scheme. The 256-character capability of ASCII and EBCDIC is too small to
handle the characters that are used by other languages such as Arabic, Japanese and
Chinese.
 The Unicode coding scheme is designed to solve this problem. It uses two bytes (16
bits) to represent one character. Unicode will have more than 65,000 different
characters. This can cover all the world’s languages.

8. ASCII code
 ASCII pronounced as "ask-key" stands for the American
Standard Code for Information Interchange and was
proposed by ASA (American Standard Association) in 963
and was finalised in 1968.ASCII is a standard of 7-bit code
used to represent characters, which include letters,
numbers and punctuation marks.
 7 bits allow the computer to encode a total of 128
characters for the numbers 0-9, uppercase and lowercase
letters A-Z and a few punctuation symbols. However this 128
bit code only suitable for english language speaking users.
 IBM and Apple expanded the amount of space reserved for
the character codes to 8-bits, equivalent to 1 byte.

9. ASCII enables
manufacturers to produce
components that are
assured to operate
correctly in a computer.
ASCII was established to
ASCII makes it possible
achieve compatibility
for humans to interact
between various types of
with a computer. It also
data processing equipment
enables users to purchase
making it possible for the
components that are
components to
compatible with their
communicate with each
computer configurations
other successfully.
Functions
of ASCII
codes

10. When you press a
key, for example the
letter D on your
keyboard, the
electronic signal is
sent to the CPU for
the computer to
process and store in
memory.
In this example, Every character is
the letter D is converted to its
converted to corresponding
01000100. binary form.
When the
computer is
finished The computer the
processing the processes the
byte, the software letter as a
installed in the byte., which
system convert actually a series of
the byte back on and off of
which is then electrical states.
displayed in the
screen.

11. Text
• You can enter data by pressing the keys on
the keyboard
Graphic
• A digital camera allows you to take
pictures and store the photographed
images digitally
Audio
• Input the speech, music and sound effects
entered into the computer
Video
• Input of motion images captured into the
computer by special input devices.

12. Central
Processing
Unit (CPU)
Ports
Expansion
and Slot
Connectors
Components
of
motherboard
Expansion
RAM Slot Cards

13. Information and
document are stored in
computer storage so
that it can be retrieved
whenever they are
needed later on.
Storage
Computer storage is
the holding of data in
an electromagnetic
form for access by a
computer processor.

14. Function of Computer Storage
Help users store programs and data to be used at a
later time
Stores instructions from a computer programs

15. Definition of operating system
 Set of programs that schedule
tasks, allowcates storage and presents a
default interface to the user between
applications.
Function of the operating system are :
 Starting a computer
 Providing a user interface
 Managing data and programs
 Managing memory
 Configuring devices