Post on 05-Apr-2018
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System board is complex printed circuitboard (PCB), which is the central partof many electronic systems, particularlythe computer.
The basic purpose of the system boardlike a backplane which is to provide the
electrical and logical connections bywhich the other components of thesystem communicate.
Definition of system board
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Types of System Boards
Primary purpose of system board To house the CPU and allow all devices to
communicate with it
Two popular types AT (older)
ATX (newer)
AT and ATX differ not in overall performance,but in size, convenience features, type ofcase into which they fit, and type of powerconnection they have
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Summary of AT and ATX
Boards
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AT and ATX Boards
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System Board Components
A CPU and itsaccompanying chipset
A system clock
ROM BIOS
A CMOS
configuration chipand its battery
RAM
RAM cache
A system bus with
expansion slots Jumpers
Ports that come
directly off the board Power supply
connections
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System Board
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System Board
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Selecting a System Board(cont)
CPU types and speeds
Chip set on the board
Memory cache type and size Types and number of expansion slots
Type of memory
Maximum amount of memory you canput on the board; incremental amountsby which memory can be upgraded
continued
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Selecting a System Board
Type of case
ROM BIOS
Type of keyboard connector Presence/absence of proprietary video &/or
proprietary local bus slots
Presence/absence of IDE adapters and SCSI
controller Presence/absence of COM ports, LPT ports,
and mouse port
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Major Manufacturers of System
Boards
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The CPU and the Chip Set
Microprocessor chips are made by Intelor one of its competitors
Common model numbers 8088, 8086, 80286 (historical interest)
386 (occasional)
486 and Pentium (most familiar)
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Attributes for Rating CPUs
CPU speed measured in megahertz
Efficiency of programming code
Word size (internal data path size) Data path
Maximum number of memory addresses
Amount of memory included with the CPU Multiprocessing ability
Special functionality
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Relating CPU Attributes to Bus
Architecture
Number of memory addresses
Determined by the number of traces, or
wires, on the bus that are used for memoryaddresses
Data path size
Determined by the width of the bus datapath, or the number of parallel wires in thebus data path
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The Earlier Intel CPUs
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The Earlier Intel CPUs
Voltages used by CPUs
Early CPUs: 5 volts
Later versions of 80486Sx and 80486DX4: 3.3volts
First Pentium: 5 volts
All other Pentiums: 3.3 and 2.8 volts
Coprocessor used with older CPUs Performs calculations for the CPU at a faster
speed that the CPU
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The Pentium and Its
Competitors
True 64-bit chip
Both the data path and word size are 64
bits
Two arithmetic logic units
Can perform two calculations at the same
time
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Comparing Chips
Bus speed
Speed or frequency at which the data on
the system board is moving
Processor speed
Speed or frequency at which the CPU
operates Usually expressed in megahertz
continued
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Comparing Chips
Multiplier Factor by which the bus speed or
frequency is multiplied to get the CPUclock speed
Memory cache A small amount of faster RAM that stores
recently retrieved data, in anticipation ofwhat the CPU will request next, thusspeeding up access
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Location of L1 and L2 Caches
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Types of Pentium CPUs
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Classic Pentium
The first Pentium (introduced in 1993)
No longer manufactured
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Pentium MMX (Multimedia
Extension)
Targets the homemarket
Speeds up graphicalapplications
Performs well withgames and
multimedia software
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Pentium Pro
Recommended for 32-bit applications thatrely heavily on fast access to large amountsof cache memory
First Pentium to offer Level 2 cache insideCPU housing
Popular for computing-intensive workstations
and servers Does not perform well with older 16-bit
applications software written for DOS orWindows 3.x
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Pentium II
Popular choice for a powerful businesscomputer using graphics applications, such
as 3-D graphic manipulation, CAD, andmultimedia presentations with graphics,motion video, and sound
Designed for graphics-intensive workstations
and servers First Pentium to use a slot instead of a socket
to connect to the system board
continued
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Pentium II
Celeron processor Low-end Pentium II processor that targets the low-
end multimedia PC market segment
Uses Level 2 cache within processor housing
Works well with Windows 9x
Xeon processor Fast, high-end Pentium II processor designed
exclusively for powerful servers and workstations
Supports up to eight processors in one computer
Recommended for use with Windows NT andUNIX operating systems
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Pentium III
Uses Slot 1 and runs with the 100-MHzmemory bus with a processor speed of
500 MHz Introduced Intels new performance
enhancement called SSE, a new
instruction set designed to improvemultimedia processing even further
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The Pentium Competitors
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Competitors of the Advanced
Pentiums
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Competitors of the Advanced
Pentiums
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Competitors of the Advanced
Pentiums
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CPUs That Use RISC
Technology
CPU is limited to a very few instructionsthat can execute in a single clock cycle
Can process much faster when fewcomplex calculations are required
Ideal for video or telecommunications
applications Easier and cheaper to manufacture
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CPU Cooling Fans
Maintaintemperature at 90 to
110 degrees F Used to prevent
system errors and toprolong the life of
the CPU
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CPU Slots and Sockets
The physical connection used to connect theCPU to the system board
Four most common types Socket 7
Used on 66MHz boards
Super Socket 7
Used on 100MHz boards Socket 8
Slot 1
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Types of Sockets Used by CPUs
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Socket Comparisons
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The ZIF (Zero Insertion Force)
Socket
Uses a small lever to apply even forcewhen installing the microchip into socket
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Pentium II and Pentium III
Chips
CPU is completely enclosed within ablack housing
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CPU Voltage Regulator
Controls the amount of voltage on the systemboard
Dual voltage CPU Requires two different voltages, one for internal
processing and the other for I/O processing
Single voltage CPUs
Requires one voltage for both internal and I/Ooperations
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CPU Voltage Regulator
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The Chip Set
Set of chips on the system board thatcollectively controls the memory cache,
external buses, and some peripherals
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Chip Set Manufacturers
Intel Corporation
AMD, Inc.
Cyrix Corporation Silicon Integrated
Systems Corp.(known as SiS)
StandardMicrosystems Corp.
UnitedMicroelectronicsCorp.
VIA Technology, Inc.
VLSI Technology
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The Intel Chip Set Family
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Chip Sets that Compete with
Intel
VIA and AMD
VIA Apollo VP2/97
AMD-640 () SiS
Genesis
Trinity
5591/92 AGP
ALi
Aladdin Pro II
Aladdin V VIA
Apollo MVP3
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Intel Dominates the Chip Set
Market
Chip sets are more compatible withPentium family of CPUs
Huge investment in research anddevelopment
PCI bus
Universal serial bus Advanced graphics port (AGP)
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ROM BIOS
There is one ROM chip on the systemboard that contains BIOS, which
manages the startup process (startupBIOS) and many basic functions of thesystem (system BIOS)
Identifying name of BIOS manufacturer
Appears at beginning of boot process
On top of the chip (larger than most chips)
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ROM BIOS
Does the BIOS support Plug and Play?
Does the BIOS support large hard
drives? Is the BIOS chip a Flash ROM chip?
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The Total BIOS in your System
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Plug and Play BIOS
Plug and Play A technology in which the operating
system and BIOS are designed toautomatically configure new hardwaredevices to eliminate system resourceconflicts (such as IRQ and port conflicts)
Common in ROM BIOS made after 1994 ESCD (extended system configuration
data)
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When BIOS Is Incompatible
with Hardware or Software
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When BIOS Is Incompatible
with Hardware or Software
Most new devices are supported bydevice drivers
Upgrade BIOS with Flash ROM
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When BIOS Is Incompatible
with Hardware or Software
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Flash ROM
EEPROM (electronically erasableprogrammable read-only memory)
Allows you to upgrade system BIOSwithout having to replace the ROM chip
S Si f
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Sample Web Site for Flash
ROM BIOS Upgrades
continued
S l W b Si f Fl h
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Sample Web Site for Flash
ROM BIOS Upgrades
RAM (R d A
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RAM (Random Access
Memory)
In older machines
Existed as individual chips socketed to the
system board in banks of nine chips each Each blank held one byte by storing one bit
in each chip; ninth chip held a parity bit
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Current Types of RAM
Dynamic RAM (DRAM) Most commonly used type of system memory
Access speeds range from 70 to 50 nanoseconds
Hold data for a very short time
Requires refreshing every few milliseconds
Static RAM (SRAM) Contains information without the need for
refreshing, as long as the computers power is on
Hold data until power is turned off
More expensive than traditional DRAM
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Dynamic Memory
Types
Parity
Error-checking scheme in which a ninth, orparity, bit is added
Value of parity bit is et to either 0 or 1
Non parity
ECC (error checking and correction)
Detects and corrects errors
M t P l T f RAM
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Most Popular Types of RAM
Modules
P ili M
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Prevailing Memory
Technologies
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Static Cache Memory
Two kinds
L1
Contained on the CPU microchip L2
External to the chip
Housed either on the system board or inside the
CPU case
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Wait States
A clock tick in which nothing happens,used to slow down the CPU so the rest
of system-board activity can keep up
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Buses and Expansion Slots
Earliest PC
Had only a single and simple bus (8-bit ISA
bus) Todays PCs
Have four or five buses, each with different
speeds, access methods, and protocols
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Bus Evolution
Data path and speed
Local buses (system buses)
Work in sync with the CPU and the system clock Example: memory bus
Expansion buses
Work asynchronously with the CPU at a much
slower rate Example: ISA bus
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Why So Many Buses?
Speeds of different hardwarecomponents evolve at different rates
Single speed for all components is nolonger practical
S t b d B i
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System-board Buses in
Common Use
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What a Bus Does
Draws electrical power
Carries control signals that coordinate
all activity Passes memory addresses from one
component to another
Passes data
Se en B s Connections on
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Seven Bus Connections on
Expansion Cards
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Buses
ISA bus 8-bit industry standard architecture bus used on
the original 8088 PC
Micro channel architecture (MCA) bus A proprietary IBM PS/2 bus, seldom seen today,
with a width of 13 or 32 bits and multiple mastercontrol, which allowed for multitaskiing
EISA (extended ISA) bus 32-bit bus that can transfer 4 bytes a a time at a
speed of about 20 MHz
continued
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Buses
Universal serial bus (USB) Designed to make installation and
configuration of I/O devices easy, providingroom for as many as 127 devices daisy-chained together
Uses only a single set of resources for alldevices on the bus
Expected to eventually replace serial andparallel ports
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USB Ports
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FireWire
An expansion bus that can also beconfigured to work as a local bus
Expected to replace the SCSI bus,providing an easy method to install andconfigure fast I/O devices
Also called IEEE 1394
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Local I/O Buses
A local bus that provides I/O deviceswith fast access to the CPU
Must connect to the CPU by way of thememory bus
Example of a Proprietary Local
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Example of a Proprietary Local
Bus
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Local I/O Buses
VESA (Video Electronics StandardsAssociation) VL bus Used on 80486 computers for connecting 32-bit
adapters directly the the local processor bus Has been replaced with the PCI bus
PCI (peripheral component interconnect) bus Common on Pentium computers
Runs at speeds of up to 33 MHz, with a 32-bit-wide data path
Serves as the middle layer between the memorybus and expansion buses
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VESA Local Bus
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PCI Bus
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PCI Bus
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Accelerated Graphics Port
A slot on a system board for a videocard that provides transfer of video data
from the CPU that is synchronized withthe memory bus
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Accelerated Graphics Port
Bus Comparisons and Bus
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Bus Comparisons and Bus
Speeds
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On-Board Ports
Ports that are directly on the systemboard, such as a built-in keyboard port
or on-board serial port
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Hardware Configuration
Communicates to the CPU what hardwarecomponents are present in the system andhow they are set up to interface with the CPU
Provided on system board in three ways
DIP switches
Jumpers
CMOS (retains data even when computer isturned off)
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Chapter Summary
System board
Central site of computer logic circuitry
Location of the most important microchip inthe computer, the CPU