Chapter 4
System Unit
Professor Michael J. Losacco
CIS 1110 – Using Computers
Overview
Chapter
4
Describe System Unit Components
Identify Motherboard Components
Describe Processor Functions
Explain Computer Data Representation
Differentiate Memory Types
Differentiate Ports & Connectors
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System Unit
Chapter
4
Case Containing Electronic Components
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Common Components
Chapter
4
Processor
Memory
Adapter Cards
Video
Sound
Modem
Network
Ports
Drive Bays
Power Supply
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Motherboard
Chapter
4
Main Circuit Board in System Unit
Contains
Processor
Memory
Adapter Cards
Chips
Integrated Circuits
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Processor
Chapter
4
Central Processing Unit (CPU)
Interprets & Executes Basic Instructions
Components
Control Unit
Directs & Coordinates Operations
Arithmetic Logic Unit (ALU)
Arithmetic (+-*/)
Comparison (=<>)
Logical (and or not)
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Processor
Chapter
4
System Clock
Controls Timing of All Operations
Generates Ticks
Regular Electronic Pulses
Smallest Unit of Time Recognized by a Device
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Processor
Chapter
4
System Clock
Processor Speed Measured by Ticks/Second
MHz – One Million Ticks/Second
Type 100 Words/Minute = 8 Characters/Second
8088 Processor @ 4.77 MHz
Character ► 50,000 Other Tasks ► Character
GHz – One Billion Ticks per Second
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Processor
Chapter
4
Machine Cycle
Fetch
Obtain Instruction From Memory
Decode
Translate Instruction to Commands
Execute
Carry Out Command
Store
Write Result to Memory
CPU Executes 1-3+ Cycles per Tick
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Processor
Chapter
4
Machine Cycle Example
1) Fetch instruction: “Get number at address 123456”
2) Decode instruction
3) Execute: ALU finds the number (which is 5)
4) Store: The number ‘5’ is stored in a register
5 – 8) Repeat steps for another number (which is 6)
9) Fetch instruction: “Add number in Reg1 to Reg2”
10) Decode instruction
11) Execute: ALU adds the numbers
12) Store: The answer is stored in a register
13) Fetch instruction: “Display answer on screen”
14) Decode instruction
15) Execute: Display answer on screen
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Processor
Chapter
4
Cooling Systems
Heat Sink
Component that Cools Processor
Heat Pipe
Used in Notebooks
Liquid Cooling
Continuous Fluid Flow Transfers Heat Away
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Data Representation
Chapter
4
Binary
Most Computers are Digital
Recognize Two Discrete States
On / Off
Equivalent Numbering System
Bits (Binary Digit)
Two Unique Digits
0/1
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Data Representation
Chapter
4
Byte
Eight Bits Grouped Together
Represent
Numbers
Uppercase & Lowercase Letters
Punctuation
Special Characters
3
5
D
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Data Representation
Chapter
4
Coding Systems
ASCII
PC
EBCDIC
Mainframe
Unicode
Other Languages
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Memory
Chapter
4
One or More Chips on Motherboard
Each Byte Stored in Unique Location
Address
Stores Three Basic Categories of Items
OS & Other System Software
Application Program Instructions
Data Being Processed & Resulting Info
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Memory
Chapter
4
Sizes
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Memory
Chapter
4
RAM (Random Access Memory)
Read From / Written To by Processor
Volatile
Content Lost When Power is Absent
More = Faster Operation
DRAM (Dynamic)
Standard
SRAM (Static)
MRAM (Magnetoresistive)
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Memory
Chapter
4
Location
Memory Resides on Small Circuit Board
Memory Module
Memory Slots Hold Memory Modules
On Motherboard
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Memory
Chapter
4
System Requirements
Based on Types of Applications Used
Cache
Speeds Computer Processes
Stores Frequently Used Instructions & Data
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Memory
Chapter
4
ROM (Read Only Memory)
Stores Permanent Data & Instructions
Non-volatile
Types
Firmware – Permanently Written Data
BIOS (Basic Input / Output System)
Sequence of Instructions to Start Computer
PROM – Blank
EEPROM – Electrically Erasable PROM
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Memory
Chapter
4
Flash
Non-volatile
Can be Erased & Reprogrammed
Used in
Cell Phone
Digital Camera
MP3 Player
USB Storage
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Additional Functionality
Chapter
4
Expansion Slots & Adapter Cards
Expansion Slot
Socket on Motherboard Holds Adapter Card
Adapter Card
Enhances System Unit
Provides Connections to Peripherals
Plug n’ Play
Automatically Configured When Installed
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Additional Functionality
Chapter
4
Port
Connects Peripheral to System Unit
Connector
Joins Cable to Peripheral
Male or Female
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Additional Functionality
Chapter
4
Ports & Connectors
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Additional Functionality
Chapter
4
USB (Universal Serial Bus)
Printer, Digital Camera, Phone, Flash, etc.
Bluetooth
Wireless
Firewire
Data Transfer
IrDA
Wireless Data Transfer
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Bus
Chapter
4
Pathway Used to Communicate
On Motherboard
Allows Devices to Communicate with Each Other
Data Bus
Address Bus
Bus Width
Word
Number of Bits Processor can Use at Once
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Other Components
Chapter
4
Bay
Opening Inside System Unit
Used to Install Additional Equipment
Typically Holds Disk Drives
Power Supply
Converts AC Power into DC Power
Fan Keeps System Unit Components Cool
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Maintenance
Chapter
4
Clean Device Once or Twice a Year
Turn Off & Unplug Device
Compressed Air to Blow Out Dust
Clean Case Exterior
Antistatic Wipe
Clean Monitor
Cleaning Solution & Soft Cloth
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