BAIT1003 Chapter 2: The components of the system unit

1. BAIT1003 IT
Fundamentals
Chapter 2
The Components of
System Unit

2. Objectives
SYSTEM UNIT
Motherboard
Processor
Ports &
Connectors
Data
Representation
Buses
Memory
Bays
Expansion Slots
& Adapter Card
Power Supply

3. The System Unit
• The system unit is a case (or sometimes called
chassis) that contains electronic components of
the computer used to process data.
• System units are available in a variety of shape
and sizes (form factor).

4. The System Unit

5. Inside System Unit
• The inside of the system unit on a desktop
personal computer includes:
Drive bay(s)
Power supply
Sound card
Video card
Processor
Memory

6. The System Unit - Motherboard
• The motherboard or system board is the main
circuit board of the system unit
– A computer chip contains integrated circuits

7. Processor
• The processor, also called the central processing
unit (CPU), interprets and carries out the basic
instructions that operate a computer.
– Processor contain a control unit (CU) and an
arithmetic logic unit (ALU). These two components
work together to perform processing operations.

8. Processor

9. Processor
• Most processor chip manufacturers now offer multicore processors.
– A multi-core processor is a chip with two or more
separate processors
– A dual-core processor is a single chip that contains
two separate processors
– A quad-core processor is a single chip that contains
four separate processors

10. Processor – Control Unit &
Arithmetic Logic
• Processors contain a Control Unit (CU) and an
Arithmetic Logic Unit (ALU).
– The control unit is the component of the processor
that directs and coordinates most of the operations
in the computer.
– The arithmetic logic unit performs:
• Arithmetic operations (+, -, *, /)
• Comparison operations (<,>,>=,)
• Logical operations (AND, OR, NOT)

11. Processor – Machine Cycle
• For every instruction, a processor repeats a set of
four basic operations, which comprise a machine
cycle.
1.
2.
3.
4.
Fetching
Decoding
Executing
Storing

12. Processor – Machine Cycle
Fetching
It is the process of obtaining a program
instruction or data item from memory.
Decoding
It is the process of translating the instruction
into signal the computer can execute.
Executing
It is the process of carrying out the
commands.
Storing
It is the process of writing result to memory.

13. Processor – Machine Cycle

14. Processor – Machine Cycle
Most current personal computers support
pipelining.
– Processor begins fetching a second instruction before it
completes the machine cycle for the first instruction.
– Processor that use pipelining are faster because they do
not have to wait for one instruction to complete the
machine cycle before fetching the next.

15. Processor – Machine Cycle

16. Processor – Registers
• A processor contains small, high-speed storage
location called registers.
• It temporarily hold data and instructions.
• Register functions include:
– Storing the location from where an instruction was
fetched
– Storing an instruction while the control unit decodes
it
– Storing data while the ALU computes it.
– Storing the result of a calculation.

17. Processor – Registers
Storing the
result of a
calculation
Storing data
while the ALU
computes it
Storing the
location from
where an
instruction
was fetched
Storing an
instruction
while the
control unit
decodes it

18. Processor – System Clock
• The processor relies on a
small quartz crystal circuit
called the system clock to
control the timing (speed) of
all computer operations.
• The pace of the system clock
is called the clock speed, and
is measured in gigahertz
(GHz).

19. Processor – Processor Cooling
• A processor chip generates heat that could cause
the chip to burn up. It require additional cooling
technologies to dissipate processor heat.
Heat sinks
It is a small ceramic or metal
component with fins on its surface that
absorbs and disperses heat.
Liquid cooling technology
It uses a continuous flow of fluid, such
as water and glycol, in a process that
transfer the heated fluid away.

20. Processor – Parallel Processing
• Parallel processing uses multiple
processors simultaneously to
execute a single program or task
• It divides a single problem into
portions so that multiple
processors work on their
assigned portion of the problem
at the same time.
• It requires special software that
recognized how to divide the
problem and then bring the
results back together again.

21. Data Representation
• Human speech is analog because it uses continuous
(wave form) signal that vary in strength and quality.
• Most computers are digital. They recognize only two
discrete status: on and off. This is because computer are
electronic devices powered by electricity.
– The digit 0 represents = OFF
– The digit 1 represents = ON

22. Data Representation
• The computer uses a binary system because it
recognized only two states.
– It has just two unique digits, 0 and 1, called bits.
– A bit is the smallest unit of data the computer can process
and it not very informative.
– 8 bits = 1 byte (a byte) provide enough different
combinations of 0s and 1s to represent 256 individual
characters likes:
• Numbers
• Uppercase and lowercase letter of the alphabet
• Punctuation marks and others.

23. Data Representation - Example

24. Data Representation
• The combination of 0s and 1s that represent characters
are defined by patterns called a coding scheme.
• Example:
• ASCII (American Standard Code for Information
Interchange) is the most widely used coding scheme
to represent data for English and western European
languages.
• Unicode—coding scheme capable of representing all
world’s languages

25. Data Representation – ASCII
Example

26. Memory
• Memory consists of electronic components that
store instructions waiting to be executed by the
processor, data needed by those instructions,
and the results of processing the data
• Stores three basic categories of items:
The operating
system and other
system software
Application
programs
Data being
processed and the
resulting
information

27. Memory – Memory Sizes
• Memory size means the number of bytes the
chip or device has available for storage.
• Memory size is measured in kilobytes (KB or K),
megabytes (MB), gigabytes (GB), or terabytes
(TB)

28. Memory – Random Access
Memory (RAM)
• Also called main memory.
• It can read from and written to by the processor and
other devices.
• Most RAM is volatile, which means it losses its contents
when power is removed from the computer.
• 3 types of RAM:
1. Dynamic RAM
2. Static RAM
3. Magnetoresistive RAM

29. Memory – Random Access
Memory (RAM)
Dynamic RAM
Static RAM
Magnetoresistive
RAM
Chips must be reenergized constantly
or they lose their
contents.
Chips are faster and
more reliable than
any variation of
DRAM. These chips do
not have to be reenergized as often as
DRAM. It much more
expensive.
Stores data using
magnetic charges
instead of electrical
charges. MRAM has
greater storage
capacity, consumes
less power, and has
faster access times .

30. Memory – Random Access
Memory (RAM)
• RAM chips usually reside on a memory module,
which is a small circuit board.
• Memory slots on the motherboard hold
memory modules.

31. Memory – Random Access
Memory (RAM)
• The amount of RAM necessary in a computer often
depends on the types of software you plan to use.
• Examples:
– 2GB or less (home user and business users)
– 2GB to 8GB (users requiring more advanced multimedia)
– 8GB and up ( power user creating professional graphics)

32. Memory – Random Access
Memory (RAM)

33. Memory – Cache
• Most of today’s computer improve their
processing time with cache.
• Memory cache helps speeds the processes
of the computer because it stores
frequently used instructions and data.
• Types of memory cache:
– L1 cache
– L2 cache
– L3 cache

34. Memory – Cache
L2 cache slower than L1
but has larger capacity
(64KB-16MB)
L2 advanced transfer cache
(ATC) is faster, built directly
on processor chip
Has very small capacity
(32KB to 64KB)
L3 cache is
separate from
processor chip on
motherboard (L3
is only on
computers that
use L2 advanced
transfer cache)
(8MB- 24MB)

35. Memory – Read Only Memory
(ROM)
• ROM refers to memory chips storing permanent
data and instructions.
• The data on ROM chips cannot be modified.
• ROM is non-volatile, which means its contents
are NOT lost when power is removed from the
computer.

36. Memory – Read Only Memory
(ROM)
• Manufacturers of ROM chips often record data,
instructions, or information on the chips when they are
manufacture the chips. These Rom chips called
firmware.
– Firmware contain permanently written data.
– A PROM (programmable read-only memory) chip is a blank
ROM chip that can be written to permanently.
– EEPROM (electrically erasable programmable read-only
memory) chip, allows a programmer to erase the microcode
with an electric signal.

37. Memory – Flash Memory
• Flash memory is a type of nonvolatile memory
that can be erased electronically and rewritten.
• Most computers use flash memory to hold their
startup instructions because it allows the
computer easily to update its contents.
• Flash memory chips also store data and
programs on many mobile computer and
devices, such as smart phone, PDA, portable
media players , and digital camera.

38. Memory – Flash Memory

39. Memory – CMOS
• Complementary Metal-Oxide Semiconductor
• Some RAM chips, flash memory chips and other
memory chips use CMOS technology because it
provides high speeds and consumes little power.
• CMOS technology uses battery power to retain
information even when the power to the
computer is off.
• Examples:
– Can keep the calendar, date, and time current even
when the computer is off.

40. Memory – Memory Access Times
• Access time is the amount of time it takes the
processor to read data, instruction, and information
from memory.
• Computer’s access time directly affects how fast the
computer processes data.
– Measured in nanoseconds

41. Expansion Slots & Adapter Cards
• An expansion slot is a socket on the motherboard that can hold
an adapter card.
• An adapter card enhances functions of a component of the
system unit and/or provides connections to peripherals.
– Examples: Sound card & video card
Sound card
Enhances the sound generating
capabilities of a personal
computer by allowing sound to
be input through a microphone
and output through external
speakers.
Video Card (graphics card)
Converts computer output into a
video signal that travels through
a cable to the monitor, which
displays an image on the screen.

42. Expansion Slots & Adapter Cards
- Examples

43. Expansion Slots & Adapter Cards
• With Plug and Play, the computer automatically can
configure adapter cards and other peripherals as
you install them.
• Having plug and play support means you can plug in
a device, turn on the computer, and then
immediately begin using the device.
• Unlike adapter cards that require you to open the
system unit and install the card on the motherboard,
you can change a removable flash memory device
without having to open the system unit.

44. Expansion Slots & Adapter Cards
• Hot plugging, allow you to insert
and remove the removable flash
memory and other device while
the computer is running.
• Removable flash memory
includes:
• Memory cards
• USB flash drives
• PC Cards/ExpressCard
modules

45. Ports & Connectors
• A port is the point at which a
peripheral attaches to or
communicates with a system
unit so that the peripheral can
send data and receive
information from the computer.
• A connector joins a cable to a
port. A connector at one end of
a cable attaches to a port on the
system unit, and a connector at
the other end of the cable
attaches to a port on the
peripheral.

46. Ports & Connectors
• On a notebook computer, the ports are on the
back, front, and/or sides

47. Ports & Connectors - Examples

48. Ports & Connectors – USB Ports
• A USB (Universal Serial Bus Port)can connect up to 127
different peripherals together with a single connector.
• You can attach multiple peripherals using a single USB
port with a USB hub
• Examples of the devices that connect to a USB port:
–
–
–
–
Mouse
Printer
Digital camera
Game console

49. Ports & Connectors – Firewire
Ports
• It is similar to a USB port in
that it can connect multiple
types of devices that require
faster data transmission
speeds, such as digital video
cameras, digital VCDs, color
printer, scanner, digital camera
and DVD drive.
• FireWire port allows you to
connect up to 63 devices
together.

50. Ports & Connectors – Other Ports
Bluetooth port
It uses radio waves to transmit data between two devices.
Bluetooth devices have to be between about 33 feet of each
other.
SCSI port
A special high speed parallel port that allows you to attach SCSI
peripherals such as disk drive and printer.
eSATA Port
It allows you to connect an external SATA hard disk to a
computers. eSATA connections provide up to 6 times faster data
transmission speeds than external hard disk.
IrDA port
Transmit data via infrared light waves. To ensure nothing
obstructs the path of the infrared light wave, you must align the
devices.
Serial port
It is a type of interface that connects device to the system unit
by transmitting data one bit at a time.
MIDI port
It allows people to connect the system unit to a musical
instrument, such as electronic keyboard.

51. Ports & Connectors – Other Ports
- Examples
• A Bluetooth
wireless port
adapter converts a
USB port into a
Bluetooth port
• A smart phone might
communicate with a notebook
computer using an IrDA port

52. Ports & Connectors – Port
Replicators & Docking Stations
• A port replicator is an
external device that
provides connections to
peripherals through
ports built into the
device
• A docking station is an
external device that
attaches to a mobile
computer or device

53. Buses
• A bus allows the various devices both inside and attached to the
system unit to communicate with each other.
• Buses are used to transfer bits:
– from input devices to memory, from memory to the processor, from the
processor to memory, and from memory to output or storage device.
• Buses consists of two parts:
– Data bus is used to transfer actual data
– Address bus is used to transfer information about where the data should
reside in memory.
• The size of a bus, called the bus width, determine the number of
bit that the computer can transmit at one time.
– 32 bits bus can transmit 32 bits (4 bytes) at a time.

54. Buses
2 types of buses: System Bus & Expansion Bus
• System Bus
– It is part of the motherboard and connects the
processor to the main memory.
• Expansion Bus
– It allows the processor to communicate with
peripherals.

55. Buses

56. Bays
• A bay is an opening
inside the system unit
in which you can
install additional
equipment.
• A drive bay is a
rectangular opening
that typically holds
disk drives.

57. Power Supply
The power supply converts the wall
outlet AC power into DC power
Some external peripherals have an AC
adapter, which is an external power
supply

58. Summary
SYSTEM UNIT
•
•
•
•
•
•
•
Motherboard
Control Unit
Arithmetic Unit
Machine Cycle
Registers
System Clock
Processor Cooling
Parallel Processing
•
•
Processor
Ports &
Connectors
•
•
•
USB
Firewire
Port replicators &
Docking stations
Binary system
ASCII code
Data
Representation
Buses
•
•
System bus
Expansion bus
•
•
•
•
•
•
•
Memory sizes
RAM
Cache
ROM
Flash Memory
CMOS
Memory Access Time
Expansion Slots
& Adapter Card
Memory
Bays
Power Supply
•
AC power to DC
power