The document discusses the key components inside a computer system unit including the motherboard, processor, memory, expansion slots, ports, and buses. It explains how the processor executes instructions through a machine cycle of fetching, decoding, executing, and storing. Memory is described as either volatile RAM or non-volatile ROM/flash, and how it represents data through bits and bytes. The document also provides guidelines for cleaning the interior and exterior of a computer system unit.

1. CHAPTER TWO
Discovering Computers
Fundamentals,
2011 Edition
Living in a Digital World

2. Objectives Overview
Differentiate among various
styles of system units on
desktop computers,
notebook computers, and
mobile devices
Describe the control unit
and arithmetic logic unit
components of a processor,
and explain the four steps in
a machine cycle
Define a bit and describe
how a series of bits
represents data
Differentiate among the
various types of memory
2

3. Objectives Overview
Describe the purpose
and types of expansion
slots and adapter cards
Differentiate between a
port and a connector,
and explain the
differences among a USB
port and other ports
Describe the types of
buses in a computer
Understand how to clean
a system unit on a
computer or mobile
device
3

4. The System Unit
• The system unit is a case that contains electronic
components of the computer used to process data
• Also called the chassis
4

5. The 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
Motherboard
ports
Bus Line
5

6. The System Unit
• The motherboard is the main circuit board of the
system unit
– A computer chip contains integrated circuits
– Contain expansion slots,
processor chips,
memory slots.
– Also called system board
6

7. Processor
• The processor, also called the central processing
unit (CPU), interprets and carries out the basic
instructions that operate a computer
– Contain a control unit and an arithmetic logic unit
(ALU)
Multi-core
processor
Dual-core
processor
Quad-core
processor
7

8. multi-core processor
• A multi-core processor is a
single computing component with two or more
independent actual processors (called "cores"), which
are the units that read and execute program
instructions.[1] The instructions are ordinary CPU
instructions such as add, move data, and branch, but
the multiple cores can run multiple instructions at the
same time, increasing overall speed for programs
amenable to parallel computing.[
• used across many application domains including
general-purpose,embedded, network, digital signal
processing (DSP), and graphics.
Discovering Computers Fundamentals, 2011 Edition
Chapter 4
8

9. Dual-core processor
• A dual-core processor has two cores (e.g. AMD
Phenom II X2, Intel Core Duo)
Discovering Computers Fundamentals, 2011 Edition
Chapter 4
9

10. Quad-core processor
• a quad-core processor contains four cores (e.g.
AMD Phenom II X4, Intel's quad-core processors,
see i3, i5, and i7 at Intel Core)
Discovering Computers Fundamentals, 2011 Edition
Chapter 4
10

11. Processor
Click to view Web Link,
click Chapter 4, Click Web
Link from left navigation,
then click Multi-Core
Processors below Chapter 4
11

12. Processor
• The control unit is the component of the
processor that directs and coordinates most of
the operations in the computer
• The arithmetic logic unit (ALU) performs
arithmetic, comparison, and other operations
12

13. Processor : Machine cycle
( how processor work)
• For every instruction, a processor repeats a set of
four basic operations, which comprise a machine
1 cycle: Instruction
cycle
st
cycle (step 1 & 2)
2nd cycle: Execution
cycle (step 3 & 4)
13

14. Processor
The system clock controls the
timing of all computer
operations
•The pace of the system clock is called
the clock speed, and is measured in
gigahertz (GHz)
14

15. Data Representation
Most computers are digital
Digital signals are in one of two states: on or off
• The binary system uses two unique digits (0 and 1) called
bits
• Bits – binary digits
• Bytes – eight bits grouped together as a unit
• Provides enough different combination of 0s and 1s to
represent 256 individual characters ( numbers,
uppercase, lowercase, punctuation mark and other)
15

16. Data Representation
A computer circuit represents
the 0 or the 1 electronically by
the presence or absence of an
electrical charge
Eight bits grouped together as a
unit are called a byte. A byte
represents a single character in
the computer
16

17. Data Representation
Bit
1
1
0
0
1
0
0
1
0
Byte
0
0
1
1
1
0
1
Byte
Word
17

18. Data Representation
• ASCII (American
Standard Code for
Information
Interchange) is the most
widely used coding
scheme to represent
data
18

19. Data Representation
19

20. 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
20

21. Memory
• Each location in memory has an address
• Memory size is measured in kilobytes (KB or K),
megabytes (MB), gigabytes (GB), or terabytes
(TB)
21

22. Memory
• The system unit contains two types of memory:
Volatile memory
Nonvolatile memory
Loses its contents when
power is turned off
Does not lose contents
when power is removed
Example includes RAM
Examples include ROM,
flash memory, and
CMOS
22

23. Memory: RAM
• Also know as primary storage/ primary memory/
main storage/ internal storage/ main memory.
• Memory keeps the instruction and data for
whatever programs you happen to be using at
the moment.
• Memory chips that can be read from and written
to by processor.
• The more RAM a computer has, the faster it
responds.
23

24. Memory
24

25. Memory
• RAM chips usually reside on a memory module
and are inserted into memory slots
25

26. Memory : Volatile memory
• Three basic types of RAM chips exist:
Dynamic RAM
(DRAM)
Static RAM (SRAM)
Magnetoresistive
RAM (MRAM)
26

27. Memory: Dynamic RAM (DRAM)
• Must be continuously refreshed by CPU or it loses
its contents.
• Used for personal computer memory because of
its size and cost advantage.
27

28. Memory: Static RAM (SRAM)
• Retains its contents with intervention from CPU
• Faster and more expensive than DRAM
• static RAM chips are preferred when energy
efficiency is a concern.
• Static RAM chips are often used in cars, household
appliances and handheld electronic devices
28

29. Memory
• The amount of RAM necessary in a computer
often depends on the types of software you plan
to use
• Memory cache speeds the processes of the
computer because it stores frequently used
instructions and data
29

30. Memory: Memory cache
30

31. Memory: ROM
Read-only memory (ROM) refers to memory
chips storing permanent data and instructions
• It is not lost when computers power is turned off.
• Contains program and data permanently recorded into
memory at the factory
• Cannot be changed by user
• Not volatile : contents do not disappear when power
is lost.
31

32. Memory
• Flash memory can be
erased electronically
and rewritten
• Used with PDSs, smart
phone, printers, digital
cameras, automotive
devices, audio players,
digital voice recorders
and pages.
32

33. Memory : CMOS
– CMOS technology provides high speeds and
consumes little power
– Stand for Complementary Metal-Oxide
Semiconductor memory.
– Used in some RSM chips, flash memory chips
and other types of memory chips.
– Uses battery power to retain information when
other power is turned off
– Stores date, time and computers startup
information.
33

34. Memory
• Access time is the amount of time it takes the
processor to read from memory
– Measured in nanoseconds
34

35. Expansion Slots and 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
– Sound card and video card
35

36. • An ExpressCard module adds memory, storage, sound,
fax/modem, communications and other capabilities to
notebook computers.
36

37. Expansion Slots and Adapter Cards
• Removable flash memory includes:
– Memory cards, USB flash drives, and PC
Cards/ExpressCard modules
37

38. Ports and Connectors
A port is the point at which a peripheral attaches to or
communicates with a system unit (sometimes referred to as
a jack)
A connector joins a cable to a port
5 categories of ports: serial ports, parallel port, USB port,
FireWire ports, Special-purpose ports.
38

39. Ports and Connectors
39

40. Ports and Connectors
• On a notebook computer, the ports are on the
back, front, and/or sides
40

41. Ports and Connectors
• A USB 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
41

42. Ports and Connectors
• Other types of ports include:
Firewire
port
Bluetooth
port
SCSI port
eSATA port
IrDA port
MIDI port
42

43. Ports and Connectors
• 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
43

44. Buses
• A bus allows the various
devices both inside and
attached to the system unit
to communicate with each
other
– Data bus
– Address bus
• A computer can have these
basic types of buses:
– System bus
: connect processor and RAM
– Backside bus
: determines number of bits
transmitted at one time.
– Expansion bus
: allows processor to
communicate with
peripherals
44

45. Bays
• A bay is an opening
inside the system unit in
which you can install
additional equipment
– A drive bay typically
holds disk drives
45

46. 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
46

47. Putting It All Together
Home
Intel Core 2 Quad or
Intel Core 2 Duo or AMD
Sempron
Minimum RAM: 2 GB
Small Office/
Home Office
Intel Core i7 or
Intel Core i7 Extreme or
AMD Athlon X2 or AMD
Athlon II X2 Dual-Code
Mobile
Intel Core i7 Extreme or
AMD Turion X2
Minimum RAM: 2 GB
Minimum RAM: 4 GB
47

48. Putting It All Together
Power
Enterprise
Intel Itanium 2 or
AMD 6-Core Opteron or
Intel Quad Core Xeon
Intel Core i7 or
Intel Core i7 Extreme or
AMD Athlon X2 or AMD
Athlon II X2 Dual-Core
Minimum RAM: 8 GB
Minimum RAM: 4 GB
48

49. Keeping Your Computer
or Mobile Device Clean
Clean your computer or mobile device once or twice a year
Turn off and unplug your computer or mobile device before
cleaning it
Use compressed air to blow away dust
Use an antistatic wipe to clean the exterior of the case and a
cleaning solution and soft cloth to clean the screen
49

50. Summary
Components of the
system unit
How memory stores
data, instructions, and
information
Comparison of various
personal computer
processors on the
market today
Sequence of operations
that occur when a
computer executes an
instruction
How to clean the
exterior and interior of
a system unit
50

51. CHAPTER TWO
Discovering Computers
Fundamentals,
2011 Edition
Living in a Digital World