GRADE 8 - COMPONENTS OF PC COMPONENTS OF PC

COMPONENTS OF PC

1. 1
Components of a Components of a
Computer SystemComputer System

2. A SystemA System

A collection of parts

Acting together

For some defined purpose

A system has a boundary

3. A systemA system
Input Output
System
Processing

4. Examples of systemsExamples of systems

Digestive system

Banking system

Transport system
What are the parts making up these systems?

5. Components of a computer systemComponents of a computer system
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6. Computers consist of hardware and Computers consist of hardware and
software.software.
Hardware
All the machinery and
equipment in a
computer system
Software
All the instructions that
tell the computer how
to perform a task

7. Computers also consist of Computers also consist of
firmware and liveware.firmware and liveware.
Firmware
Instructions or
programs that
reside inside
Integrated Circuits
(ICs)
Liveware
All the living things
aiding computer to
work. Data entry
operators, programmers
etc

8. Computer
Hardware Software
Application
Software
Utility
Software
CPU MemoryI/OEtc.System
Software

9. HardwareHardware
Physical devices you can see and touch

Screens

Keyboards

Printers

10. Hardware ‘Discussion’Hardware ‘Discussion’
Hardware also refers to objects such as disks,
disk drives, boards, and chips. In contrast, software
is untouchable. Software exists as ideas, concepts,
and symbols, but it has no substance.
Books provide a useful analogy. The pages and
the ink are the hardware, while the words,
sentences, paragraphs, and the overall meaning are
the software. A computer without software is like a
book full of blank pages -- you need software to
make the computer useful just as you need words to
make a book meaningful.

11. HardwareHardware
11
(Single In-line Memory Module)

12. HardwareHardware
CPU: Central Processing Unit
–Brain of a computer
–Manages all devices and performs the actual
processing of data
–Carry out instructions given by user
–For Personal Computer (PC), the CPU is usually
included in a single Integrated Circuit (IC) chip
(called Microprocessor)
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13. HardwareHardware
–Nowadays, one or more microprocessors (chips)
can be used to form a CPU
 Parallel Processing
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14. HardwareHardware
Input and Output devices (I/O devices)
–Interface between the outside world and the
computer system
–Input devices: keyboard, mouse
–Output devices: monitors, printers
–Other I/O devices: scanner, joystick, touch
screen, …
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15. HardwareHardware

Memory
–Internal memory / Main memory

Random Access Memory (RAM)
–Main feature 1: volatile
 Requires continuous supply of electrical
power to retain information
–Main feature 2: cheap in terms of bytes per
dollar
 Suitable for large volume data storage
–Functions:
 Receive commands / data from keyboard
 Store information ready to be sent to
output
 Store currently running programs/their
data
 Store immediate data generated by the
currently running programs
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16. HardwareHardware
Another kind of memory
Read Only Memory (ROM)
–Main feature 1: non-volatile
 data retain even when the power is off
–Main feature 2: relatively expensive and can only be
written once
 suitable for storing essential data but in small volume
–Usually used for system boot up and basic control of I/O
devices
 When a computer first powers up, nothing is in RAM
 Need ROM to store the instructions to set up various
I/O devices, such as disk interface card, video adapter
card, sound card, etc.
–ROM is used to store BIOS (Basic Input/Output Systems)
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17. HardwareHardware
Storage devices
–External memory
Non-volatile
Used to store programs/data for future use
Also used when the capacity of the internal
storage is insufficient to keep the currently
running programs and the data required
Floppy disks, hard disks, CD ROMs, Magnetic
tapes
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18. HardwareHardware
Main differences between storage &
memory:
–Larger capacity in storage than in memory
–Data in storage are retained while data in
memory disappear when power is off
–Storage is much cheaper than memory
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19. 19
Instructions /
DataCPU
I DII I
III I
I IIDD
DDDDDD
00010203040506070809
10111213141516171819
Memory
Address
Control
I/O
I: Instruction
D: Data
Buses
–Path along which “bits” are transmitted
–Linking up the CPU, Memory and I/O devices
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21
22
I/O
I/O
External
Storage

20. Put all the hardware together and…Put all the hardware together and…

21. You still need the software!You still need the software!
System software
(Operating System)
Helps the computer
perform essential
operating tasks and
enables the
application software to
run and…

22. System SoftwareSystem Software
Exists primarily for the computer itself
Hides the hardware complexities
Brings the different hardware configurations
into common platforms and accessible by
the users
Consists of several programs, the most
important one is the operating system
(master control program that runs the
computer)
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23. You still need the software!You still need the software!
Utility Software:
Also known as service routine, utility software
helps in the management of computer
hardware and application software. It
performs a small range of tasks. Disk
defragmenters, systems utilities and virus
scanners are some of the typical examples of
utility software.

24. Operating SystemOperating System
Master control program
–Manage all resources of the computer
CPU, memory, disk, monitor, network, …
–Co-ordinate running programs
Runs as soon as the computer boots
up, until the computer shuts down
Usually store in the hard disk and load
into the memory when the computer
starts
Need the help of BIOS for I/O devices
E.g. Windows, Unix, Linux
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BIOS
Operating
System
I/O Devices
Other
resources

25. How the OS is loaded into memory?How the OS is loaded into memory?
•When power up, nothing is in RAM. No control is
possible to the hard disk to load the OS
•CPU starts to read the BIOS instructions stored in the
ROM
•Things that normally perform
–Initialize all I/O devices: hard disk, video, mouse, keyboard,
CD-ROM, etc
–Load the bootstrap loader of the operating system to RAM
–Start to execute the bootstrap loader in RAM
•The bootstrap loader further loads the other part of the
operating system to the RAM
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26. 26
CPU
Main Memory (RAM)
BIOS
(Stored in
ROM)
Hard Disk
Mother Board
Disk Interface
Video
Interface
Monitor
Disk Interface
Video
Interface
OS
Bootstrap loader
OS

27. You still need the software!You still need the software!
Application software
Enables you to perform
specific tasks--solve
problems, perform work,
or entertain yourself.

28. Application SoftwareApplication Software
Developed to fulfill certain needs of users
Either customized or packaged
–Customized software
Designed for a particular customer according
to their needs
Payroll, inventory control, …
–Packaged software
Developed for general use
Microsoft word, excel, Access, power-point, …
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29. Software ‘Discussion’ (2)Software ‘Discussion’ (2)
The distinction between software and hardware is
sometimes confusing because they are so integrally
linked. Clearly, when you purchase a program, you
are buying software. But to buy the software, you
need to buy the disk (hardware) on which the
software is recorded.
Software is often divided into two categories.
Systems software includes the operating system and
all the utilities that enable the computer to function.
Applications software includes programs that do real
work for users. For example, word processors,
spreadsheets, and database management systems
fall under the category of applications software.

30. 30
Software - ProgrammingSoftware - Programming
•Programming – the way to generate a program
•Computer can only understand 0 and 1
•The most direct way to communicate with the computer is to use
0 and 1  Machine Language Programming
• 0110001111000010
0001000111100011
:
:
0011000100001000
1000001001010101
Machine
Language
Program
Very tedious and can make error easily

31. 31
Software – Low level language
Assembly Language Programming
•Assembly Language is created to help humans to instruct the
CPU to work
•By using a tool called Assembler, assembly language program can
be converted into machine language program
Assembler
0110001111000010
0001000111100011
:
:
0011000100001000
1000001001010101
mov ax, #0
add ax, $1234
:
:
mov bx, #22
mov $2345, bx
Assembly Language Machine Language

32. 32
Software - High Level Language
Programming
•Assembly language programming is still too complicated for
general users
•They are far from human used language
e.g. “Set W equal to W plus X minus Y divided by Z”
“Repeat the next sequence of instructions until X is less
than 0 or Y equals Z”
•A high level language is required to close the gap between human
and computers

33. 33
Machine Language Programming
–No application nowadays
Assembly Language Programming
–Advantage: Less complicated than Machine Language. Usually
generate more efficient code than HLL
–Disadvantage: Need the understanding of CPU structure. Still difficult
to program
–Application: Sometimes used in the programming of embedded
systems (e.g. CPU of printer, washing machines, etc.)
High Level Language Programming (such as C/C++)
–Advantage: Need the least amount of effort to write a program
–Disadvantage: The program written may not be optimal (depends on
the compiler)
–Application: For large scale programs

34. Hardware & Software SummaryHardware & Software Summary
User interacts with application software
System software enables the application
software to interact with computer CPU
and help the computer to manage its
internal resources (hardware)
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35. Hardware & Software SummaryHardware & Software Summary
35
Banking System / Web Browser /
Media player
Physical devices /
Micro-architecture level
Operating System
GUI /
Command interpreter
Application
Software
System Software
Hardware