Computer Application
Introduction to computers
Didam A Mahmud
Objective
Hardware component
Hardware
Input Device
Output
Device
System Unit
Storage
Device
Communications
Device
System unit
Box-like case
containing electronic
components used to
process data
The System Unit
The inside of the system unit on a desktop personal computer
includes:
Processor
2. Memory module
3. Expansion cards
power supply
drive bays
1.
a)
b)
c)
d)
4.
Sound card
Modem card
Video card
Network interface card
processor
memory
ports
sound card
Ports and
Connectors
network card
modem card
video card
Motherboard
Also called the system board
Is the main circuit board inside the computer
It holds many of the crucial electronic components
Main components of motherboard are
1.
2.
3.
4.
5.
Central processing unit (CPU)
Memory
Video card
Sound card
Network connect card(NIC) the
CPU
Sometimes referred to as the central processor unit , but more
commonly called processor.
the CPU is the brains of the computer where most
calculations take place.
Interprets and carries out the basic instructions that operate a
computer
In terms of computing power, the CPU is the most important element
of a computer system.
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Two Main components of CPU
Arithmetic/Logic Unit (ALU)
Perform two types of operations
Arithmetic (+,-,*,/) and logic(<,>,=)
Control Unit
Tell the rest of the computer how to carry out a programs
instructions
Works with a program counter (address of next instruction)
It directs the movement of electronic signals between memory,
instructions and arithmetic logic unit.
Direct control signals between the CPU and I/O devices.
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Processor
Machine cycle
There are four operations of Machine Cycle
Step 1. Fetch
Obtain program instruction or data item from memory
Step 2. Decode
Translate instruction into commands
Step 3. Execute
Carry out command
Step 4. Store
Write result to memory
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CPU Register
Temporary storage location used by the CPU
1. Stores location from where instruction was fetched
2. Stores an instruction while it is being decoded
3. Stores data while the ALU processes it
4. Stores the results of a calculation
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Pipelining
CPU begins fetching second instruction before completing
machine cycle for first instruction
Results in faster processing
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system clock
Synchronizes all computer operations
Each tick is a clock cycle
Faster clock speed means the CPU can execute more
instructions each second
Clock speed (clock rate) measured in megahertz (MHz) and
gigahertz (GHz)
MHz - one million ticks of the system clock
GHz one billion ticks of the system clock
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Heat Sink and Heat Pipe
A processor chip generates heat that could cause the chip to
burn up
Processor Requires additional cooling unite, tow main types
are:
1. Heat sink: Small ceramic or metal component with fins on
its surface that absorbs and ventilates heat produced by
electrical components
2. Heat pipe: smaller device for notebook computer
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Parallel Processing
Using multiple processors simultaneously to execute a
program
Speeds processing time
Requires special software to divide
up a problem and bring the results
back together again
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Expansion Slots and Expansion Cards
Expansion slot: A location on the
motherboard into which
expansion cards are inserted
Expansion card: A circuit board
used to add additional
functionality or to attach a
peripheral device
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Common Types of Expansion Cards
1.
2.
3.
4.
There are Four common types of expansion cards
Video card also called video adapter or graphics card
Sound card
Network interface card (NIC) also called a network card
Modem card also called an internal modem
. Plug
and Play is that the computer automatically can
configure cards and other devices as you install them
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Ports and Connectors
Used to connect external
devices to the system unit
Connector joins cable to
peripheral
Most located on the back of
the system unit
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Common ports
Serial port
2. Parallel port
3. universal serial bus (USB) port
4. special-purpose port
1.
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Serial Port
Transmits one bit of data at a time
Used to connect devices that do not
require fast transmission rates
mouse
keyboard
modem
Two common types
25-pin
9-pin
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parallel port
Connects devices that can transfer
more than one bit at a time
Usually used for printers
Two newer types
EPP (Enhanced Parallel Port)
ECP (Extended Capabilities Port)
IEEE 1284 is a standard that
specifies how older and newer
peripheral devices transfer data to
and from a computer
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Universal Serial Bus port (USB)
Can connect up to 127 different
peripheral devices with a single
connector type
Supports newer peripherals
Supports hot plugging and Plug
and Play
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How are multiple USB devices connected?
Daisy Chain
Devices connected together
outside the system unit in a
chain
USB hub
Plugs into the USB port on the
computer
Contains multiple USB ports
Computer with
USB port
Computer with
USB port
USB
hub
device
1
device
3
device
2
device
1
device
4
device
2
device
3
device
4
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special-purpose ports
1394 port (FireWire) connect multiple devices
MIDI port musical instrument digital interface
SCSI port small computer system interface
IrDA port transmit data via infrared light waves
FIR (fast infrared)
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Buses
Electrical channels that allow various
devices inside the computer to
communicate with each other
Bus width determines the number of
bits transmitted at one time
Word size determines the number of
bits the processor can interpret and
execute at a given time
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Types of Buses
System bus Part of the motherboard that connects the
processor to main memory
2. Expansion bus Allows the processor to communicate with
peripheral devices
1.
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Bays
An open area inside the system
unit used to install additional
equipment
Drive bays
Used for disk drives
External drive bay
Also called exposed drive bay
Accessible from outside the system
unit
Internal drive bay
Also called hidden drive bay
Concealed entirely within the
system unit
DVD-ROM
drive
CD-RW
drive
Zip drive
empty drive
bay
floppy disk
drive
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power supply
The power supply to a
computer is its main source
of power and it crucial for the
computer to run.
The power supply converts
the wall outlet AC power
into DC power
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Summary
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