Transcript The Components of the System Unit

The Components of
the System Unit
Jeremy Lukianovich
The system unit
The system unit is the case that contains
the electronic components that make up
a computer.
The mother board is the main circuit
board that all of the electronic
components are in some way
connected to.
Computer Chip
The computer chip is a small piece of
etched semi-conducting materiel, such
as silicone.
There are two types of attachments
1) DIP-dual inline package (two rows
of metal feet)
2) PGA-Pin grid array (large number
of pins covering the surface of the chip)
Processor-(CPU)
The Control unit- directs and coordinates
activities in the computer
The arithmetic logic unit- performs
comparisons, arithmetic, and logic operations
Machine cycle- the repeated 4 steps to all
computer actions (1-fetching, 2-decoding, 3executing, 4-storing)
Registers-Small storage locations in the
processor. This is a high speed temporary
storage area.
The system clock- controls timing of all
computer operations
Processor installation and upgrades

Three types
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Chip for Chip-Replace existing chip
Piggy back-stack new one on top of old chip
Daughterboard upgrade-new chip on adapter card that
plugs into motherboard
Heat sinks and heat pipes

ceramic or metal finned components that help dissipate
heat
Coprocessors

a secondary chip that aids the main processor, thereby
increasing the performance of the computer
Parallel processing

Using multiple computer processors to increase the
speed of the processor.
Data Representation
Computers use digital representation

Binary code
1=on
 0=off

A single digit is a bit
8 bits equal a byte
Two coding systems
ASCII
 EBCDIC
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Memory
RAM (Random access memory)
Primary memory type
 Read from and written by programs
 If power loss RAM is lost, unless stored
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DRAM (Dynamic RAM)
 Must be reenergized or will lose memory
 Several types
SRAM (Static RAM)
 Most stable but expensive
More RAM the faster the computer will be
Cache

Memory Cache
 Stores frequently used data - speeds up computer
 3 types
 L1-built into processor
 L2-advanced transfer cache
 L3-separate cache, must have L2 to work

Disk Cache (see chapter 7)
ROM (Read only memory)

Stores permanent data and instructions
Flash memory
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Nonvolatile memory that can be erased electronically
Often contains startup instructions due to its adaptability
CMOS (Complimentary metal-oxide semiconductor)

Technologically advanced materiel that produces high speeds with low
power draws.
Memory access times

The time it takes a computer to do an operation, this can be as little as
10 nano-seconds
Expansion Slots and Adapter
cards
Expansion slots

Slot on computer that can hold a circuit board that in some
way increases the performance of the computer.
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Sound cards
Video cards
Modem cards
Network cards
PC cards and Flash memory cards
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PC cards-a thin device that plugs into a computer and adds
memory, storage, sounds, modem, communications, fax, or
other abilities to the computer.
Flash memory cards-a card that allows a user to add data
from a mobile device (such as a PDA) to a laptop.
Ports and connectors
Serial ports-a port that connects two devices and
transmits 1 bite at a time, good for devices that do no
require high transfer rates.
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Mouse
Keyboard
Modem
Parallel ports-a port connects devices but transmits
data at a higher rate than a serial port

Printers
USB ports-universal serial bus port

Can connect up to 127 peripherals together on one port.
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Daisy chain them
USB hub
Hot plugging (plugging in a device without first shutting the
computer down.
Special purpose ports
Firewire port
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Similar to USB
Faster than USB
MIDI port (musical instrument digital interface)
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Used to connect a instrument to a computer
SCSI (small computer system interface
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Attach such devices as disk drives and printers
Daisy chain up to 7 to 15 devices
IrDA (infrared data ssociation)
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Transfer data via infrared light waves, completely
wireless
Bluetooth
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Radio waves to transmit information
Similar to IrDA but you don’t need to line up the
devies
Buses
Buses
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The channels within a computer chip which the bits take to travel
from one point to another.
Bus width dictates how many bits a computer may transmit and
one time
Faster the bus speed the faster the programs will run.
System Buses
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Part of the mother board
Connects processor to main memory
Expansion buses
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Channels outside the main processor that transmit data into and
out of the processor
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ISA (industry standard bus)-slowest
Local- high speed bus that connects things such as disk drives
Accelerated Graphics port-improves speed which 3D graphics move
USB and Firewire
PC Card bus
Bays
Opening in system where you can insert additional
equipment
Drive bays- rectangular openings which usually
house disk or CD drives.
Power Supplies
Battery powered-primarily laptops
AC adaptor-allows the DC powered computer to be
plugged into a AC power supply (wall socket)
A cooling fan is generally mounted near the power
input
Mobile Computers and
Devices
Laptops-small computers that have folding screens, very
portable

Contain many miniaturized components which generally raises the
price
Tablet PC-entire computer in the shape of a tablet.
PDA-handheld computing device, generally contain a phone
book, basic word processing, and little else.