Chapter 5 The System Unit of a Computer System 5.1System Unit88System Unit 5.2Basic Computer...
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Transcript of Chapter 5 The System Unit of a Computer System 5.1System Unit88System Unit 5.2Basic Computer...
Chapter 5 Chapter 5 The System Unit of a Computer SystemThe System Unit of a Computer System
5.1 System Unit 88
5.2 Basic Computer System 90
5.3 Central Processing Unit 91
5.4 Main Memory 93
5.5 Computer Bus System 97
5.6 Port and Interface 99
5.15.1 The System UnitThe System Unit (2) (2)
System Unit of a PC (p.89) motherboard, interface cards and
storage devices Ports or Interface card
Other devices, like keyboards, monitors and printers,
are connected to the ports/interface cardsthrough cables.
Notebook computer houses almost all of its electronic components in the system unit
Chapter 5 Computer System Unit
5.25.2 Basic Computer SystemBasic Computer System A basic computer system consists of the following
hardware components: 1. Central Processing Unit (CPU) 2. Main memory 3. Input devices 4. Output devices 5. Secondary storage 6. Communication devices
For PC: The CPU and Memory are plugged on the motherboard. Those devices Those devices
which connected to the motherboard are called Peripheral devices.which connected to the motherboard are called Peripheral devices.
Chapter 5 Computer System Unit
The Components of a ComputerThe Components of a Computer
Peripherals (devices) items attached to system unit
Input Input
Input
Input
Output
Output
Output
Communication
5.3 5.3 CPUCPU (2)- (2)-ComponentsComponents
1. Control Unit (CU) controls the overall operations interprets program and sets off action controls peripheral devices.
2. Arithmetic and Logic Unit (ALU) carries out computational jobs, including
calculation, comparison and decision.
Chapter 5 Computer System Unit
Do Q. 3 on p. 102
ALU
How ALU and Control Unit work?
Main Memory
add two numbers
10 7 Control Unit
interpret instructions
perform operations
10 + 7 = 17
Retrieve an instruction
Tell ALU how to perform an operation
3. Registers high-speed storage locations temporarily hold data and instructions during
processing e.g. cache memory in CPU/ video accelerating
card/ hard disk; buffer in printer etc.
5.3 5.3 CPU (4)-SpeedCPU (4)-Speed
Clock speed number of clock cycles or ticks per second each instruction required a certain number of ticks to
complete. measured in hertz (Hz)
Mega (M) is a prefix representing one million (106). Giga (G) represents one billion (109).
For example, a 800 MHz PowerPC produces ~800 million clock cycles in one
second a 2.2 GHz Pentium 4 produces 2.2 ~billion clock cycles in one
second.
Chapter 5 Computer System Unit
5.45.4 Main memory Main memory (2)(2)
1. Random Access Memory (RAM) p.93 hold instructions and data as computers are running volatile
Chapter 5 Computer System Unit
CPU RAM Hard Diskloading
saving
5.45.4 Main memory Main memory (3)(3)
2. Read only memory (ROM) Store instructions and data permanently Non-volatile Contents can be read but cannot be changed also called Firmware
software (program) is stored in a chip instead of disc.
ROM chip may store programs for booting called the Basic Input/Output System (BIOS)Basic Input/Output System (BIOS)
Chapter 5 Computer System Unit
5.45.4 Main memory Main memory (5) - (5) - ComparisonComparison
Chapter 5 Computer System Unit
RAM ROM CMOS
Permanence volatile non-volatile non-volatile
Flexibility read and write read only read and write
Type ofinformation
data andinstructions being
processed
system program anddata
configuration data
Size largest small smallest
Upgradable yes; memory sizecan be increased
no no
5.45.4 Main memory Main memory (6) -(6) -Memory SizeMemory Size
Memory Size measured in byte (Ch. 2) exists in multiples of 1,024 bytes (kB) 1 kB = 1,024 bytes 1 Megabyte (MB) = 1,024 x 1,024 bytes 1 Gigabyte (GB) = 1,024 x 1,024 x 1,024 bytes
Chapter 5 Computer System Unit
5.45.4 Main memory Main memory (7) - (7) - DataData Access Access
Access mode of memory data is Direct Accesssince each byte has a unique addressData retrieve or store is efficiently
Opposite to Sequential Access e.g. searching from a tapesearching from a tape or finding from a word document
Chapter 5 Computer System Unit
5.5 5.5 Buses in a computerBuses in a computer (1) (1)
Bus Channel/wire for data transfer between
A. (1) memory and (2) peripheral devicesB. (1) memory and (2) CPU
A bus consists of threethree parts: Control bus Address bus Data bus
Chapter 5 Computer System Unit
Data bus transfer actual data
Address bus transfer information about the location of data
Control bus indicate the direction of data transfer coordinate the timing of events during the transfer
5.5 5.5 Buses in a computerBuses in a computer (2) (2)
Two basic types of bus: System bus (or processor bus)
channel between the CPU and
the main memory.
Peripheral buses channels between the main memory
and other devices,
Peripheral bus
Chapter 5 Computer System Unit
1. ISA bus
2. PCI bus
3. SCSI bus
4. USB
5. AGP bus
5.5 5.5 Buses in a computerBuses in a computer (3) (3)
Bus Width Number of bits (amount of data) transmitted at one
time Affects the overall performance of a computer
Chapter 5 Computer System Unit
5.6 5.6 Ports and Interface cardsPorts and Interface cards (1) (1)
Ports Connect motherboard (RAM) to Peripheral buses
/devices Interface cards
Inserted into Interface slots on the motherboard to connect the Peripheral buses (increases the number of ports of the system unit).
Chapter 5 Computer System Unit
5.6 5.6 Ports and Interface cardsPorts and Interface cards (2) (2)
Chapter 5 Computer System Unit
Port Name Peripheral devices
1. Keyboard and mouse port Keyboard, mouse
2. Serial port Mouse, modem, graphic tablet
3. Parallel port Printer
4. SCSI port Fast devices, e.g. hard disk
5. USB port large range of devices
6. 1394 port DV camera
7. IrDA port (Infrared Data
Association) Wireless devices
8. PC card port (for notebook
computers only)
PC cards, e.g. Network interface card,
hard disk, sound cards, radio
transceiver etc.
TaskTask
Read more catalogue of Computer System (PC + Notebook)
Try to understand the type and function of each part.
Best Computer Ltd.
CPU 4.2 GHz
RAM 2 GB
ROM 2 MB
Hard disk 160 GB
DVD drive 48X / 24X / 12X
Expansion slot 4 PCI
Sound card On-board
Network card Built-in Ethernet adaptor
Wi-Fi 802.11a/g built-in wireless card and antenna
Operating System Magic 300