Chapter 4 Objectives
Differentiate among various styles of system units
Identify chips, adapter cards, and other components of a motherboard
Describe the components of a processor and how they complete a machine cycle
Identify characteristics of various personal computer processors on the market today
Define a bit and describe how a series of bits represents data
Explain how programs transfer in and out of memory
Differentiate among the various types of memory
Describe the types of expansion slots and adapter cards
Explain the difference among a serial port, a parallel port, a USB port, and other ports
Describe how buses contribute to a computer’s processing speed
Identify components in mobile computers and mobile devices
Next

The System Unit
What is the
?
 Case that contains electronic components of the computer used to process data
 Sometimes called the chassis system unit system unit system unit system unit
Next p. 4.04 Fig. 4-1

The System Unit
What are common components inside the system unit?






Processor
Memory
Adapter cards

Sound card

Modem card

Video card

Network card
Ports
Drive bays
Power supply power supply ports drive bays processor memory sound card video card modem card network card p. 4.03 Fig. 4-2
Next

The System Unit
What is the
?



Main circuit board in system unit
Contains adapter cards, processor chips, and memory chips
Also called
Expansion slots for adapter cards adapter cards p. 4.04 Fig. 4-3 motherboard processor chip memory chips memory slots
Next

The System Unit
What is a
?


Small piece of semi-conducting material on which integrated circuits are etched
 Integrated circuits contain many microscopic pathways capable of carrying electrical current
Chips are packaged so they can be attached to a circuit board
Click to view animation p. 4.04 Fig. 4-4 dual inline packages (DIP) holds memory chips pin grid array (PGA) package holds processor chips
Next

Central Processing Unit
What is the
?
 Interprets and carries out basic instructions that operate a computer
 Control unit directs and coordinates operations in computer

Arithmetic logic unit
(ALU) performs arithmetic, comparison, and logical operations
Input
Devices
 Also called the processor
Data
Processor
Information
Data
Information
Memory Information
Information
Data
Information
Output
Devices
Storage
Devices p. 4.05 Fig. 4-5
Next

Central Processing Unit
What is a
?
 Four operations of the CPU comprise a machine cycle
Step 1. Fetch
Obtain program instruction or data item from memory
Memory
Step 4. Store
Write result to memory
ALU
Processor
Step 3. Execute
Carry out command
Control Unit
Step 2.
Decode
Translate instruction into commands p. 4.06 Fig. 4-6
Next

Central Processing Unit
What is
?


CPU begins fetching second instruction before completing machine cycle for first instruction
Results in faster processing p. 4.07 Fig. 4-7
Next

Central Processing Unit
What is a
?
 Temporary high-speed storage area that holds data and instructions
Stores location from where instruction was fetched
Stores instruction while it is being decoded
Stores data while ALU computes it
Stores results of calculation p. 4.07
Next

Central Processing Unit
What is the
?


Controls timing of all computer operations
Generates regular electronic pulses, or ticks, that set operating pace of components of system unit
Each tick is a clock cycle
Pace of system clock is clock speed
Most clock speeds are in the gigahertz (GHz) range (1 GHz = one billion ticks of system clock per second)
Processor speed can also be measured in m illions of i nstructions p er s econd (MIPS)
Click to view Web Link, then click Clock Speed below Chapter 4 p. 4.07
Next

Central Processing Unit
How do personal computer processors compare?
Click to view video
Name
Xeon ™
Itanium ®
Celeron ®
Operon ™
Comparison of Widely Used
Personal Computer Processors
™
Date
Introduced
2002
2001
2001
2000
1999
1999
1998
2003
2002
2001
1999
Clock
Speed
1 GH
Z and up
1.4–2.4 GH
Z
733–800 MH
Z
1.4–2.53 GH
Z
500–900 MH
Z
400 MH
Z
–1.2 GH
Z
266 MH
Z
–1.8 GH
Z
To come
1.53–1.6 GH
Z
1.33–1.73 GH
Z
500 MH
Z
–1.4 GH
Z p. 4.08
Next

Central Processing Unit
Which processor should you select?

The faster the processor, the more expensive the computer
Intel Processor Desired Clock Speed
Itanium ® or Xeon ® 1 GHz and up
Pentium ® family
Celeron ®
2.5 GHz and up
1.7 GHz to 2.5 GHz
Up to 1.7 GHz
1.2 GHz and up
Click to view video p. 4.10
Next

Central Processing Unit
What are the types of processor upgrades?
Chip-for chip upgrade replace the chip
Piggyback upgrade stack new chip on top of old one
Daughterboard upgrade chip is on adapter card that plugs into motherboard p. 4.10
Next

Central Processing Unit
What is a
socket?
 Allows you to install and remove chips with no force lever lever
Step 1.
Lift the lever on the socket.
Step 2.
Insert the chip.
p. 4.11 Fig. 4-10
Step 3.
Push the lever down.
Next

Central Processing Unit
What are
and
?
 Heat sink
—component
 with fins that cools processor
Heat pipe e
—smaller device for notebook computers heat sink p. 4.12 Fig. 4-11 heat sink fan
Next

Central Processing Unit
What is a
?
p. 4.12
Next

Central Processing Unit
What is
?
 Using multiple processors simultaneously to execute a program faster Processor 1
 Requires special software to divide problem and bring results together
Memory
Control Processor
Processor 2
Memory
Processor 3
Memory
Results combined
Processor 4
Memory p. 4.12 Fig. 4-12
Next

Data Representation
How do computers represent data?
 Most computers are digital
 Recognize only two discrete states: on or off

Use a binary system to recognize two states

Use Number system with two unique digits: 0 and
1, called bits (short for binary digits) p. 4.13 Fig. 4-13
Next

Data Representation
What is a
?
 Eight bits grouped together as a unit
 Provides enough different combinations of 0s and 1s to represent 256 individual characters

Numbers

Uppercase and lowercase letters

Punctuation marks p. 4.13 Fig. 4-14
Next

Data Representation
What are three popular coding systems to represent data?



ASCII
—
A merican S tandard C ode for I nformation I nterchange
EBCDIC — E xtended B inary C oded D ecimal I nterchange C ode
Unicode
—coding scheme capable of representing all world’s languages
ASCII
00110000
00110001
00110010
00110011
Symbol
0
1
2
3
EBCDIC
11110000
11110001
11110010
11110011 p. 4.14
Next

Data Representation
How is a letter converted to binary form and back?
Step 1.
The user presses the capital letter D
(shift+D key) on the keyboard.
Step 2.
An electronic signal for the capital letter D is sent to the system unit.
Step 4.
After processing, the binary code for the capital letter D is converted to an image, and displayed on the output device.
p. 4.15 Fig. 4-16
Step 3.
The signal for the capital letter D is converted to its ASCII binary code (01000100) and is stored in memory for processing.
Next

Memory
What is
?
 Electronic components that store instructions, data, and results


Consists of one or more chips on motherboard or other circuit board
Each byte stored in unique location called an address , similar to addresses on a passenger train p. 4.15 Fig. 4-17
Seat #2B4 Seat #2B3
Next

Memory
How is memory measured?
 By number of bytes available for storage
Term
Kilobyte
Megabyte
Gigabyte
Terabyte
Abbreviation
KB or K
MB
GB
TB
Approximate Size
1 thousand bytes
1 million bytes
1 billion bytes
1 trillion bytes p. 4.16 Fig. 4-18
Next

Memory
What is
?
Memory chips that can be read from and written to by processor
Also called main memory or primary storage
Most RAM is volatile , it is lost when computer’s power is turned off
The more RAM a computer has, the faster it responds
Click to view Web Link, then click RAM below Chapter 4 p. 4.17
Next

Memory
How do program instructions transfer in and out of RAM?
Operating system instructions
RAM
Operating system interface
Step 1.
When you start the computer, certain operating system files load into RAM from the hard disk. The operating system displays the user interface on the screen.
Web browser instructions
Web browser window
Step 2.
When you start a Web browser, the program’s instructions load into RAM from the hard disk. The Web browser window is displayed on the screen.
Word processing program instructions
Word processing program window
Step 3.
When you start a word processing program, the program’s instructions load into
RAM from the hard disk. The word processing program, along with the Web Browser and certain operating system instructions are in RAM. The word processing program window is displayed on the screen.
RAM
Step 4.
When you quit a program, such as the
Web browser, its program instructions are removed from RAM. The Web browser no longer is displayed on the screen.
p. 4.17 Fig. 4-19
Web browser program instructions are removed from RAM
Web browser window no longer is displayed on desktop
Next

Memory
What are two basic types of RAM chips?
Most common type
Used for special applications such as cache
Faster variations of DRAM are
SDRAM and
RDRAM
Faster and more reliable than DRAM chips p. 4.18
Next

Memory
Where does memory reside?
 Resides on small circuit board called memory module
 Memory slots on motherboard hold memory modules memory chip dual inline memory module memory slot p. 4.18 Fig. 4-20
Next

Memory
How much RAM does an application require?


Software package typically indicates
RAM requirements
For optimal performance, you need more than minimum specifications
System Requirements
Windows
®
XP Home Edition/Professional
• Intel Pentium processor at 233MHZ or higher
• AMD K6 (Athlon Duron Family processor at 233MHZ or higher
• 64 MB of RAM p. 4.19 Fig. 4-21
Next

Memory
How much RAM do you need?
 Depends on type of applications you intend to run on your computer
RAM
Use
128 to 256 MB 256 to 1 GB 1 GB and up
• Home and business users managing personal finance
• Using standard application software such as word processing
• Using educational or entertainment
CD-ROMs
• Communicating with others on the Web
• Users requiring more advanced multimedia capabilities
• Running number-intensive accounting, financial, or spreadsheet programs
• Using voice recognition
• Working with videos, music, and digital imaging
• Creating Web sites
• Participating in video conferences
• Playing Internet games
• Power users creating professional Web sites
• Running sophisticated
CAD, 3D design, or other graphics-intensive software p. 4.19 Fig. 4-22
Next

Memory
What is
?
 Helps speed computer processes by storing frequently used instructions and data
 Also called memory cache
 L1 cache built into processor
 L2 cache slower but has larger capacity
 L2 advanced transfer cache is faster, built directly on processor chip

L3 cache is separate from processor chip on motherboard (L3 is only on computers that use L2 advanced transfer cache)
Click to view Web Link, then click Cache below Chapter 4 p. 4.20 Fig. 4-23
Next

Memory
What is
?
Memory chips that store permanent data and instructions
Nonvolatile memory , it is not lost when computer’s power is turned off
EEPROM
Three types: ( e lectrically e rasable p rogrammable
Firmware
—
Manufactured with permanently written data, instructions,
PROM
( p rogrammable or information r eado nly m emory)—
Blank ROM chip onto which a programmer can write permanently r eado nly m emory)—
Type of PROM containing microcode programmer can erase p. 4.20
Next

Memory
What is
?
 Nonvolatile memory that can be erased electronically and reprogrammed
 Used with PDAs, digital cameras, digital cellular phones, music players, digital voice recorders, and pagers
Step 1.
Purchase and download MP3 music tracks from a Web site. With one end of a special cable connected to the system unit, connect the other end into the MP3 player.
Flash memory chip
To headphones
Step 3.
Plug the headphones into the MP3 player, push a button on the MP3 player, and listen to the music through the headphones.
Click to view Web Link, then click Flash Memory below Chapter 4 p. 4.21 Fig. 4-24
From computer
Flash memory card
Step 2.
Instruct the computer to copy the MP3 music track to the flash memory chip in the MP3 player.
MP3 Player
Next

Memory
What is
?
C omplementary m etalo xide s emiconductor memory
Used in some
RAM 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 computer’s startup information p. 4.22
Next

Memory
What is
?
 Amount of time it takes processor to read data from memory


Measured in nanoseconds (ns), one billionth of a second
It takes 1/10 of a second to blink your eye; a computer can perform up to 10 million operations in same amount of time
Term Speed
Millisecond
Microsecond
Nanosecond
Picosecond
One-thousandth of a second
One-millionth of a second
One-billionth of a second
One-trillionth of a second p. 4.22 Fig. 4-26
Next

Expansion Slots and Expansion Cards
Types of Adapter Cards
What is an
?


Enhances system unit or provides connections to external devices called peripherals
Also called an expansion card
Click to view Web Link, then click Adapter Cards below Chapter 4 p. 4.23 Fig. 4-27
Next

Expansion Slots and Expansion Cards
What is an
?


An opening, or socket, on the motherboard that can hold an adapter card
With Plug and Play , the computer automatically configures cards and other devices as you install them p. 4.23 Fig. 4-28
Next

Expansion Slots and Expansion Cards
What are
and
?


A PC card adds memory, sound, modem, and other capabilities to notebook computers
A flash memory card allows users to transfer data from mobile devices to desktop computers

Hot plugging allows you to insert and remove cards while computer
Click to view Web Link, then click PC Cards below Chapter 4 is running p. 4.24 Fig. 4-29–4-30
Next

Ports
What are
and
?


Port connects external devices to system unit
Connector joins cable to peripheral
 Available in one of two genders: male and female
Click to view Web Link, then click Ports and Connectors below Chapter 4 p. 4.25 Fig. 4-31–4.32
Next

Ports
What are different types of connectors?
p. 4.26 Fig. 4-33
Next

Ports
What is a
?
 Transmits one bit of data at a time
 Connects slow-speed devices, such as mouse, keyboard, modem p. 4.27 Fig. 4-34
Next

Ports
What is a
?
 Connects devices that can transfer more than one bit at a time, such as a printer p. 4.27 Fig. 4-35
Next

Ports
What are
?
USB ( u niversal s erial b us) port can connect up to 127 different peripherals together with a single connector type
PCs typically have two to four USB ports on front or back of the system unit p. 4.28
Single USB port can be used to attach multiple peripherals in a daisy chain
Second USB device connects to first USB device
First USB device connects to USB port on computer
Third USB device connects to second USB device, and so on
Next

Ports
What are
?
 Allow users to attach specialized peripherals (digital video cameras, color printers, scanners, and disk drives) or transmit data to wireless devices

FireWire port

MIDI (Musical
Instrument Digital
Interface) port

SCSI (small computer system interface) port

IrDA (Infrared Data
Association) port

Bluetooth TM port p. 4.28 Fig. 4-37
Next

Buses
What is a
?
 Channel that allows devices inside computer to communicate with each other

System bus connects processor and RAM

Bus width determines number of bits transmitted at one time

Word size is the number of bits processor can interpret and execute at a given time
Click to view Web Link, then click Buses below Chapter 4 p. 4.30 Fig. 4-38
Next

Buses
What is an
?
 Allows processor to communicate with peripherals p. 4.31 Fig. 4-39
Next

Bays
What is a
?
 Open area inside system unit used to install additional equipment
 Drive bays typically hold disk drives p. 4.32 Fig. 4-40
Next

Mobile Computers
What is a
?
 Notebook, weighing between 2.5 and 8 pounds, or mobile device such as a PDA flash memory card
PC Cards in
PC Card slots disk in floppy disk drive or
Zip
® disk drive p. 4.33 Fig. 4-41 notebook computer
PDA
CD or DVD drive battery
Next

Mobile Computers
What is in the system unit of a mobile computer?
 Motherboard, processor, and memory—also devices such as the keyboard, speakers, and display p. 4.34 Fig. 4-42
Next

Mobile Computers
What ports are on a notebook computer?
p. 4.34 Fig. 4-43
Next

Mobile Computers
What ports are on a tablet PC?
p. 4.35 Fig. 4-44
Next

Putting It All Together
p. 4.35 Fig. 4-45
Next

Components of the system unit
How memory stores data, instructions, and information
Sequence of operations that occur when a computer executes an instruction
Comparison of various personal computer processors on the market today
Chapter 4 Complete