Post on 18-Jan-2017
66CH
APT
ER
THE SYSTEM UNIT
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© 2005 The McGraw-Hill Companies, Inc. All Rights Reserved.
Competencies
Describe the function of the system clock, expansion slots, boards, and bus lines
Discuss ports, cables, and power supply
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System Clock
Important measurement indicating speed Located on a small chipProduces electrical beats
Synchronizes operationsExpressed in gigahertzFaster clock speed, faster computer
What is a gigahertz?
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System Clock
Controls speed and synchronizes operationsExpressed in megahertzFaster the clock speed, the faster the computer
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Expansion Slots and Cards
Allow for new devices to be addedOpen architectureSlots provide for expansion
Expansion cards are also called …Plug-in boardsController cardsAdapter cardsInterface cards
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Page 88-89
Section D
.. Expansion Slots and Cards
Expansion slot - long, narrow socket on the motherboard into which you can plug an expansion card
Graphics card (for connecting monitor)Modem (for transmitting data over phone or cable lines)Sound card (for connecting speakers)
Expansion card - small circuit board that provides computer with ability to control storage, input or output deviceMost computers have 4 - 8 expansion slots
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Page 88
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Page 90
Do notebook computers also contain expansion slots?Most notebook computers are equipped with a special type of external slot called a PCMCIA slot (personal computer memory card international association)Typically a notebook only has one slot, but the slot can hold more than one PC card (PCMCIA expansion cards)
PC Cards
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Page 90
PC card
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Commonly Used Expansion Cards
Video cardsModem cardsNetwork interface cards (NIC)TV tuner cards PC cards
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Page 92
Internal devicesTools required
ScrewdriverDirections
Before installingUnplug the computerGround yourself
InstallingFollow the directions
Installing a New Expansion Card
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Page 92
Some devices require software, called a device driverThe device driver sets up communication between your computer and the deviceNormally, disk or CD used only onceToday’s PCs include Plug and Play (PnP) that automatically takes care of these technical details
.. Installing a New Expansion Card
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Installing a New Expansion Card
For installing a new device, following setup is needed:
Inserting the device card into the matching slotInstalling the device driver program for the deviceConfigure the system (tedious step, requires sufficient technical background)
“Plug and Play” is a new technology for making the device installation procedure much faster and easier.
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“Plug and Play”
Hardware and software standards
Makes system expansion easy for the user
Automatically installs drivers and system configuration
System unit recognizes the new device
A plug-n-play card requires the user to:
•Switch off the system
•Insert the card
•Open the system again.
•System automatically configure itself for the newly installed device
-User is asked for the latest device driver.
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Bus Lines
Connect parts of the CPU to each other Data roadway for traveling bits
Measured as bus widthMore lanes, faster traffic
Two basic categoriesSystem busesExpansion buses
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Page 88
Section DChapter
2Input and Output Devices
Expansion slots, cards and ports: How does a computer get data from RAM to a peripheral device?
Data Bus carries data from one component to anotherI/O (computer jargon for input/output) refers to collecting data and transporting results.Expansion bus - the segment of the data bus that transports data between RAM and peripheral devices
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Types of Expansion Buses
Industry Standard Architecture (ISA) Peripheral Component Interconnect (PCI)Advanced Graphic Port (AGP)Universal serial bus (USB)FireWire buses
HPSB – high performance serial busUsed with digital camcorders & video editing software
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Page 89
The microcomputer motherboard typically has up to three types of expansion slots:
ISA - older technology, modems and slow devicesPCI - for graphics, sound, video, modem or network cardsAGP - for graphics cards
Expansion cards are built for only one type of slot
… Types of Expansion Buses
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Page 89
AGP slot
PCI slot
ISA slot
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ISA Bus
Developed by IBM for personal computers
Slow
Originally 8 bit, later expanded to 16 bit
Still used by some expansion cards
Replaced by PCI bus in the near future
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PCI Bus
Originally developed to meet demands of graphical user interfaces
High speed
32 bit or 64 bit
Widely used to connect CPU, memory, and expansion cards
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AGP Bus
Dedicated bus for acceleration of graphics
performance
Replacing the PCI bus for transfer of video data
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Other Bus Types
USBConnects directly to the PCI bus on the motherboardSupports external devices without inserting expansion cards for each device
HPSBFireWireSimilar to USB but faster
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Page 90
To connect a peripheral device to an expansion card, you plug a cable from the device into the expansion portExpansion port - any connector that passes data in and out of a computer or peripheral device
Expansion Ports
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Page 90
Network port
Modem port
Monitor port
Speaker and microphone jacks
Power plug socket
Parallel port (printer)
DB-9 serial port
USB ports
Mouse port
Keyboard port
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Ports
Socket for connecting external devices Four common ports
Serial ParallelUSB FireWire
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Serial & Parallel Ports
Serial Port
Data sent one bit at a time
Good long distance transmission of data
Parallel Port
Data sent 8 bits simultaneously
Used for short distances
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USB and HPSB Ports
USB PortReplacing serial and parallel ports FasterEach port can support more than one device
HPSB PortFireWire portsFaster then USB ports
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Page 91
USB portMost popular portMost computers feature at least 2 USB portsUSB devices
MouseScannerPrinterJoystick
Windows automatically recognizes USB devices
What’s the best port to use for connectingperipheral devices?
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Cables
Connect Input/Output devices
Mouse
Keyboard
Printer
Monitor
Newer cablesAGP
graphics monitorUSB
joy stick; scannerHPSB
video camera
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Page 90-91
Major types of expansion cables
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Power Supply
Computers require direct current (DC)DC power provided by converting alternating current (AC) from wall outlets or batteries Desktop computers use power supply unitsNotebooks and handhelds use AC adapters
AC adapter
Power Supply Unit
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Look to the Future
Wireless Technology and PDAsPersonal wearable computer
POMA®
Wireless pointing device, head mounted displayDeveloped by Xybernaut CorporationCurrently being evaluated for use in airport security