Your Interactive Guide to the Digital World
Discovering
Computers 2012 Chapter 4
System Unit Components
Objectives Overview
Differentiate among various styles of system units on
desktop computers, notebook computers, and
mobile devices
Differentiate among various styles of system units on
desktop computers, notebook computers, and
mobile devices
Identify chips, adapter cards, and other components of a
motherboard
Identify chips, adapter cards, and other components of a
motherboard
Describe the control unit and arithmetic logic unit components of a processor,
and explain the four steps in a machine cycle Describe the control unit
and arithmetic logic unit components of a processor,
and explain the four steps in a machine cycle
Identify characteristics of various personal computer
processors on the market today, and describe the ways processors are cooled
Identify characteristics of various personal computer
processors on the market today, and describe the ways processors are cooled
Define a bit and describe how a series of bits
represents data
Define a bit and describe how a series of bits
represents data
Explain how program instructions transfer in and
out of memory Explain how program instructions transfer in and
out of memory
Discovering Computers 2012: Chapter 4 2
See Page 209
for Detailed Objectives
Objectives Overview
Differentiate among the various types of memory
Differentiate among the various types of memory
Describe the purpose and types of expansion slots and adapter cards, and differentiate among slots for various removable flash
memory devices
Describe the purpose and types of expansion slots and adapter cards, and differentiate among slots for various removable flash
memory devices
Differentiate between a port and a connector, and explain the differences among a USB port, FireWire port, Bluetooth port, SCSI port, eSATA port, IrDA port,
serial port, and MIDI port Differentiate between a port and
a connector, and explain the differences among a USB port, FireWire port, Bluetooth port, SCSI port, eSATA port, IrDA port,
serial port, and MIDI port
Describe the types of buses in a computer
Describe the types of buses in a computer
Explain the purpose of a power supply and describe how it keeps
cool
Explain the purpose of a power supply and describe how it keeps
cool
Understand how to clean a system unit on a computer or
mobile device
Understand how to clean a system unit on a computer or
mobile device
Discovering Computers 2012: Chapter 4 3
See Page 209
for Detailed Objectives
The System Unit
• The system unit is a case that
contains electronic
components of the computer used to process data
Discovering Computers 2012: Chapter 4 4
Page 210 Figure 4-1
The System Unit
• The inside of the system unit on a desktop personal computer includes:
Discovering Computers 2012: Chapter 4 5
Page 211 Figure 4-2
Drive bay(s)
Drive bay(s)
Power supply
Power supply
Sound card
Sound card
Video card
Video card
Processor
Processor
Memory
Memory
The System Unit
• The motherboard is the main circuit board of the system unit
– A computer chip contains integrated circuits
Discovering Computers 2012: Chapter 4 6
Page 212 Figure 4-3
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)
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Multi-core processor Multi-core
processor
Dual-core processor Dual-core processor
Quad-core processor Quad-core
processor
Discovering Computers 2012: Chapter 4 8 Page 213
Figure 4-4
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
Discovering Computers 2012: Chapter 4 9
Page 214
Processor
• For every instruction, a processor repeats a set of four basic operations, which comprise a machine cycle
Discovering Computers 2012: Chapter 4 10
Page 215 Figure 4-5
Processor
• Most current personal computers support
pipelining
– Processor begins fetching a second instruction before it
completes the machine cycle for the first
instruction
Discovering Computers 2012: Chapter 4 11
Pages 215 – 216 Figure 4-6
Processor
The processor contains registers, that temporarily hold data and instructions The processor contains registers, that temporarily hold data and instructions
The system clock controls the timing of all computer operations
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)
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Processor
• The leading
manufacturers of personal computer
processor chips are Intel and AMD
Discovering Computers 2012: Chapter 4 13
Pages 216 – 217 Figure 4-7
Processor
• Determine how you plan to use a new computer before selecting a processor
Discovering Computers 2012: Chapter 4 14
Page 218 Figure 4-8
Processor
• A processor chip
generates heat that
could cause the chip to burn up
• Require additional cooling
– Heat sinks
– Liquid cooling technology
Discovering Computers 2012: Chapter 4 15
Pages 219 - 220 Figures 4-9 – 4-10
Processor
• Parallel processing uses multiple processors
simultaneously to execute a single program or task
– Massively parallel processing involves hundreds or thousands of processors
Discovering Computers 2012: Chapter 4 16
Page 220 Figure 4-11
Data Representation
Analog signals are continuous and vary in strength and quality
Analog signals are continuous and vary in strength and quality
Digital signals are in one of two states: on or off
Digital signals are in one of two states: on or off
• Most computers are digital
• The binary system uses two unique digits (0 and 1)
• Bits and bytes
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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
Discovering Computers 2012: Chapter 4 18
Page 221
Figures 4-12 – 4-13
ASCII character
Data Representation
• ASCII (American Standard Code for Information
Interchange) is the most widely used coding
scheme to represent data
Discovering Computers 2012: Chapter 4 19
Page 221 Figure 4-14
Discovering Computers 2012: Chapter 4 20 Page 222
Figure 4-15
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:
Discovering Computers 2012: Chapter 4 21
Page 223
The operating system and other
system software The operating system and other
system software
Application programs Application
programs
Data being
processed and the resulting
information Data being
processed and the resulting
information
Memory
• Each location in memory has an address
• Memory size is measured in kilobytes (KB or K), megabytes (MB), gigabytes (GB), or terabytes (TB)
Discovering Computers 2012: Chapter 4 22
Page 223 Figure 4-17
Memory
• The system unit contains two types of memory:
Discovering Computers 2012: Chapter 4 23
Pages 223 - 224
Volatile memory
Loses its contents when power is turned off Loses its contents when
power is turned off
Example includes RAM Example includes RAM
Nonvolatile memory
Does not lose contents when power is removed Does not lose contents when power is removed
Examples include ROM, flash memory, and
CMOS
Examples include ROM, flash memory, and
CMOS
Discovering Computers 2012: Chapter 4 24 Page 224
Figure 4-18
Memory
• Three basic types of RAM chips exist:
Discovering Computers 2012: Chapter 4 25
Page 225 Figure 4-19
Dynamic RAM (DRAM)
Dynamic RAM
(DRAM) Static RAM (SRAM) Static RAM (SRAM) Magnetoresistive RAM (MRAM) Magnetoresistive
RAM (MRAM)
Memory
• RAM chips usually reside on a memory module and are inserted into memory slots
Discovering Computers 2012: Chapter 4 26
Page 225 Figure 4-20
Memory
• The amount of RAM necessary in a computer
often depends on the types of software you plan to use
Discovering Computers 2012: Chapter 4 27
Page 226 Figure 4-21
Memory
• Memory cache speeds the processes of the computer because it stores frequently used instructions and data
Discovering Computers 2012: Chapter 4 28
Page 227 Figure 4-22
Memory
Read-only memory (ROM) refers to memory chips storing permanent data and instructions
• Firmware
A PROM (programmable read-only memory) chip is a blank ROM chip that can be written to
permanently
• EEPROM can be erased
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Page 228
Memory
• Flash memory can be erased electronically and rewritten
– CMOS technology provides high speeds and consumes little power
Discovering Computers 2012: Chapter 4 30
Pages 228 – 229 Figure 4-23
Memory
• Access time is the amount of time it takes the processor to read from memory
– Measured in nanoseconds
Discovering Computers 2012: Chapter 4 31
Page 229
Figures 4-24 – 4-25
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
Discovering Computers 2012: Chapter 4 32
Page 230 Figure 4-26
Expansion Slots and Adapter Cards
• With Plug and Play, the computer automatically can configure adapter cards and other peripherals as you install them
Discovering Computers 2012: Chapter 4 33
Pages 230 – 231 Figure 4-27
Expansion Slots and Adapter Cards
• Removable flash memory includes:
– Memory cards, USB flash drives, and PC Cards/ExpressCard modules
Discovering Computers 2012: Chapter 4 34
Page 231 Figure 4-28
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 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 A connector joins a cable to a port
Discovering Computers 2012: Chapter 4 35
Page 232
Discovering Computers 2012: Chapter 4 36 Page 232
Figure 4-29
Ports and Connectors
• On a notebook computer, the ports are on the back, front, and/or sides
Discovering Computers 2012: Chapter 4 37
Pages 232 - 233 Figure 4-30
Discovering Computers 2012: Chapter 4 38 Page 233
Figure 4-31
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
Discovering Computers 2012: Chapter 4 39
Page 234 Figure 4-32
Ports and Connectors
• Other types of ports include:
Discovering Computers 2012: Chapter 4 40
Pages 234 - 236
Firewire port Firewire
port
Bluetooth port
Bluetooth
port SCSI port SCSI port
eSATA port
eSATA port IrDA port IrDA port Serial port Serial port
MIDI port
MIDI port
Ports and Connectors
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
Discovering Computers 2012: Chapter 4 41
Page 235
Figures 4-33 – 4-34
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
Discovering Computers 2012: Chapter 4 42
Page 236 Figure 4-35
Buses
• A bus allows the various devices both inside and attached to the system unit to communicate with each other
– Data bus – Address bus
• Word size is the number of bits the processor can interpret and execute at a given time
Discovering Computers 2012: Chapter 4 43
Page 237 Figure 4-36
Buses
• Expansion slots connect to expansion buses
• Common types of expansion buses include:
Discovering Computers 2012: Chapter 4 44
Page 238
PCI bus
PCI bus PCI Express
bus
PCI Express
bus Accelerated
Graphics Port Accelerated Graphics Port
USB and FireWire bus
USB and
FireWire bus PC Card bus PC Card bus
Bays
• A bay is an opening
inside the system unit in which you can install
additional equipment
– A drive bay typically holds disk drives
Discovering Computers 2012: Chapter 4 45
Page 238 Figure 4-37
Power Supply
The power supply converts the wall outlet AC power into DC power
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
Some external peripherals have an AC adapter, which is an external power supply
Discovering Computers 2012: Chapter 4 46
Page 239
Putting It All Together
Home Intel Core i5 or Intel Core 2 i3 or
AMD Athlon II or AMD Sempron Minimum RAM: 2 GB
Small Office/
Home Office Intel Core i7 or Intel Core i7 Extreme or
AMD Phenom II or AMD Athlon II Minimum RAM: 4 GB
Mobile
Intel Core i7 Extreme or Intel Core i7 or AMD Phenom II or
AMD Turion II Minimum RAM: 2 GB
Discovering Computers 2012: Chapter 4 47
Page 239 Figure 4-38
Putting It All Together
Power Intel Xeon or Intel Itanium or
AMD Opteron Minimum RAM: 8 GB
Enterprise Intel Core i7 or Intel Core i7 Extreme or AMD Phenom II or
AMD Athlon II Minimum RAM: 4 GB
Discovering Computers 2012: Chapter 4 48
Page 239 Figure 4-38
Keeping Your Computer or Mobile Device Clean
Clean your computer or mobile device once or twice a year Clean your computer or mobile device once or twice a year
Turn off and unplug your computer or mobile device before cleaning it
Turn off and unplug your computer or mobile device before cleaning it
Use compressed air to blow away dust 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
Use an antistatic wipe to clean the exterior of the case and a cleaning solution and soft cloth to clean the screen
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Video: The Leopard with a Time Machine
Discovering Computers 2012: Chapter 4 50
CLICK TO START
Summary
Components of the system unit
Components of the system unit
How memory stores data, instructions, and
information
How memory stores data, instructions, and
information
Sequence of operations that occur when a computer executes an
instruction
Sequence of operations that occur when a computer executes an
instruction
Comparison of various personal computer
processors on the market today
Comparison of various personal computer
processors on the market today
How to clean the exterior and interior of
a system unit How to clean the exterior and interior of
a system unit
Discovering Computers 2012: Chapter 4 51
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