System Concept

1. CHAPTER 2: COMPUTER
SYSTEM
System Concept

2. Computer System
Computer is an electronic device, operating under the
control of instructions stored its own memory
 That can accept data (input)
 Process the data according to specified rules
(process)
 Produce results (results)
 Store the results for future use (storage)

3. Input -Any data and instructions entered into the memory of a
computer
- 4 types of input are text, graphics, audio and video
Input device -Any hardware component that allows users to enter data
and instructions into a computer
-Examples: keyboard, mouse, joystick, scanner
Processor / -An electronic component on a computer’s motherboard
CPU / that interprets and carries out the basic instruction that
Microprocessor operate the computer
-Examples: Intel Pentium IV, AMD Athlon
Output - Data that has been processed into a useful form, called
information
Output device -Any hardware component that present information
(processed data) to one or more people
-Examples: speaker, monitor, LCD projector, printer
Storage -A location in which data, instructions and information are
saved for future used
-Examples: CD ROM, diskette, hard disk

4. Block Diagram of the Information
Processing Cycle
INPUT PROCESS OUTPUT
STORAGE

5.  The processing unit controls all activities within the
system.
 For every instruction, the control unit repeats a set
of four basic operations called machine cycle
(fetch, decode, execute and store)

6. Machine Cycle
4 STORE FETCH 1
3 EXECUTE DECODE
2

7. Functions of CPU
 Fetch a program instructions or data item from memory
 Decode the program instructions into signals that
computer can execute
 Execute the instructions
 Store the result of instructions to the memory
 Interprets and carries out basic instructions that operate
a computer
 Control unit directs and coordinates operations in
computer
 Arithmetic logic unit (ALU) performs arithmetic,
comparison and logical operations

8. Data Representation
Bit
o A bit (short for binary digit) is the smallest unit of
data the computer can process
o The binary system is a number system that has two
unique digits, 0 and 1, called bits
o They correspond to the states of on and off, true
and false or yes and no

9. Byte
o Byte is a unit of information built from bits
o When 8 bits are grouped together as a unit, they
form a byte
o A byte provides enough different combinations of
0s and 1s represent 256 individual characters

10. Character
o One byte is equals to 8 bits
o One byte represents a single character such as the number,
letter or symbol
o Example is capital F represented by binary code
01000110 that can be understood by the computer system
o There are 3 character codes to represent characters which
are ASCII, EBCDIC and Unicode
o The 256 character capability of ASCII and EBCDIC is too
small to handle the characters that are used by other
languages such Arabic, Japanese and Chinese
8 bits = 1 byte

11. What is ASCII??
 ASCII (pronounce as-key) is an acronym for
American Standard code for Information
Interchange
 Used in most computers to represent letters,
numbers and other characters

12. Function of ASCII Code
 ASCII was established to achieve capability
between various types of data processing
equipment making it possible for components to
communicate with each other successfully
 ASCII enables to manufacturers to produce
components that are assured to operate correctly
in a computer

13. Units of Data Measurement
 KILOBYTE (KB)
1 KB = 1000 bytes Why is 1024 bytes = 1 KB?
1 KB = 210 bytes 20 = 1
 MEGABYTE (MB) 21 = 2
1 MB = 1048576 bytes 22 = 4
23 = 8
1 MB = 220 bytes
24 = 16
 GIGABYTE (GB) 25 = 32
1 GB = 1073741824 bytes 26 = 64
1 GB = 230 bytes 27 = 128
 TERABYTE (TB) 28 = 256
1 TB = 1099511627776 bytes
29 = 512
210 = 1024
1 TB = 240 bytes

14. Clock Speed Measurement
 Every microprocessor contains a system clock
 The clock speed unit is measured in hertz
 A hertz is on cycle per second
1 Hz = 1 GHz =
1 MHz =