Computer Hardware Overview

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Computer Hardware Overview

Post by ALI RAZA » Tue Oct 09, 2018 12:00 pm

Hardware and Software
A computer system is made up of a combination of hardware and software.

All of the electronic and mechanical equipment in a computer is called the hardware. Examples
• Motherboard
• Hard disk
• Power supply
• Processor
• Case
• Monitor
• Keyboard
• Mouse

The term software is used to describe computer programs that perform a task or tasks on a
computer system. Software can be grouped as follows:
System software: These are the programs that control the operation of the
computer system. Operating systems and utility programs are the most common. The
Operating System starts the computer, provides a user interface, manages the computer
memory, manages storage, manages security and provides networking and internet
facilities to mention a few of it’s capabilities. There are many OS’s on the market
including Microsoft Windows XP, Microsoft Windows Vista, Apple OS X , Unix and
Linux. Windows is by far the most commonly used OS in the world, but Linux in
particular, is making inroads into this dominance.
Utility programs perform maintenance tasks on the computer system. This includes
file management programs, uninstall programs, disk scanners and fragmentation,
backup utilities, antivirus etc. These can be included in the OS or purchased

Device drivers are programs that control particular hardware devices. They are
supplied with new hardware and must be run so they the hardware can communicate
with the OS. They are supplied with printers, graphics cards, scanners etc.

Application Software: This software is used to do non-system based tasks.
Categories include business software, engineering software, medical software,
games etc.

Sometimes, application software packages are grouped together to form
productivity suites. Examples include Microsoft Office and OpenOffice.
These combine word processing, spreadsheet, database and presentation
software with a common interface making then easier to learn. The Adobe
Creative suite combines Adobe Photoshop, Adobe Illustrator, Adobe In Design
etc. as an all-in-one graphics and web design suite. As well as common
interfaces, these suites offer great compatibility between the applications.

PC Components

A computer system is a collection of electronic and mechanical devices operating as a unit. These
devices can be sorted according to the role they play in the computer system. The main device
categories are:

The main parts of a computer system are:
  • Input devices :These devices are used to get data into the computer system.
    Processing devices :These manipulate the data using to a set of instructions called a program.
    Output devices :These are used to get data out of a computer system.
    Storage devices : The can store the data for use at a later stage.
    Communications devices :These can send the data to another computer system .
The main parts of a computer system are:

1 System Unit : The container for the motherboard, disk drives etc.
2 Monitor : The main output device for the system.
3 Keyboard : The main input device for the system.
4 Mouse : An input device allowing interaction with the system using pointing and clicking .
5 Speakers :Used to output sounds and music from the system .
System Unit Devices and Peripherals
The system unit is the main container for system devices. It protects the delicate electronic and
mechanical devices from damage. Typical system unit devices include:

• Motherboard
• CPU (Processor)
• Memory
• Disk drives
• Expansion cards - sound card, graphics card, network card etc.
• Ports - USB etc.
• Power supply

Peripherals are devices that connect to the system unit using cables or wireless technologies.
Typical peripherals include:

• Monitor
• Keyboard
• Mouse
• Speakers
• Printer
• Plotter
• Scanner

System Unit Devices

The Processor (CPU)

A processor is an integrated circuit (IC) supplied on a single silicon chip. All of the components
and pathways necessary for the movement of data around the processor are etched on this single

The processor’s function is to control the activities of the computer system. A computer program
is made up of instructions and when the program is run, the processor is responsible for carrying
out these instructions in an orderly fashion. The type of instructions the processor can execute

• Arithmetic instructions - It carries out all the addition, subtraction, multiplication
and division requested by computer programs.
• Logical instructions - It can make decisions by comparing data and acting in a
particular way depending on the result.
• Move operations - It can move data from place to place within the computer
system. This could be from memory to the processor for
addition or from memory to a printer or disk drive etc.

The speed of a processor is measured in megahertz (MHz) or Gigahertz (GHz). This is the speed
of the system clock (clock speed) within the processor and it controls how fast instructions can be

• 1 MHz - One million clock ticks every second
• 1 GHz - One billion clock ticks every second

This means that if one instruction was executed every clock tick, a 3GHz processor could execute
three billion instructions every second.
The two main computer processor manufacturers are Intel and Advanced Micro Devices (AMD).
These two companies produce almost all of the processors used in desktop and notebook

• Intel - Intel makes the Pentium and Centrino ranges of processors.
• AMD - AMD makes the Athlon and Turion ranges of processors.

The performance of these chips relative to each other is forever changing and it would be difficult
to claim one is better than the other in the long term.

The latest trend in processor manufacture is to essentially put more than one processor on a silicon
chip. These multi-core processors can have two, three or four processor cores on a single chip.
This obviously vastly increases the performance of the computer system as long as the programs
run on the systems can take advantage of the multi-cores.

Another important factor in processor choice is the amount of power a processor consumes. This
is not critical on a desktop computer but is critical on a notebook computer. AMD and Intel have
developed a range of processors optimized for mobile computers. The Turion and Centrino
processors use very little power to maximize battery life and are optimized for wireless
networking, factors that are very important in mobile computing. They also use Speed step or
Power now technology to regulate the processor power to the system requirements.
Word processing needs less processor power than CAD and the system can adjust the processor
speed to suit the program being run. This saves power and produces less heat. In a notebook
computer, this is a huge advantage.

Random Access Memory (RAM)

Known as primary storage, it is the main working memory of the computer system. Data and
programs currently in use are held in RAM. It is called random access because data can be
accessed in any order. If you are working on a drawing in Solid works, the Solid works program
and the drawing under construction are both held in RAM. RAM is volatile which means that
when the computer is turned off, the contents of RAM are lost. This is why it is essential to save
your work on a regular basis. Because of the volatility of RAM, most software programs have an
auto save feature to prevent the total loss of your work.

RAM is made in the form of integrated circuits (IC’s) in the same manner as a processor. These
IC’s are placed on a circuit board to produce a memory module. The most common RAM
technology is dynamic random access memory (DRAM).
In this technology, a transistor and a capacitor are paired to store one Bit (binary digit) of data.
In essence, if the capacitor is charged, a binary 1 is stored and if it is discharged, a binary 0 is
stored. (see the section on data representation for more on binary data). The transistor acts as a
switch to allow the capacitor’s state to be changed as required.

There is a problem with this technology. As soon as the capacitor is charged, it begins to leak. As
a result, the charge in the capacitors must be continually refreshed or they would leak to binary 0’s
resulting in corrupted data. This continuous refreshing is performed about 80 times per second and
drastically slows down the speed at which main memory can be written to and read from.

DRAM is sold in modules called DIMM’s (dual inline memory module) for desktop computers
and in modules called SODIMM’s (small outline dual inline memory module) for notebook
HP 4GB - 1600 DIMM Memory


DIMM’s and SODIMM’s are sold in modules with capacities of 256MB, 512MB, 1GB, 2GB. The
current technology is called DDR (double data ram) and there are three types. Any particular
computer system can only use one of the three type. The types are:
As can be seen from the above tables, the type of memory in a computer can have a massive
impact on the overall performance of the computer system. At the extremes, DDR-200 can be
accessed 200 million times per second while DDR3-12800 can be accessed 1600 million times per second.

Cache memory

If a computer system has a Pentium IV processor running at 3GHZ and 512MB PC-2100 DRAM
installed, every time the processor requires data from RAM it will have to slow down to the speed
of the RAM (PC-2100 = 266MHz) to access the data. As the processor continually accesses RAM,
the effective speed of the processor for these transfers will be 266MHz. This is called latency and
would effectively ruin the performance of the computer system if allowed to continue.

To overcome this problem, a small amount of fast static RAM is included in the processor. Static
RAM does not use capacitors and as a result does not need to be refreshed. Static RAM is much
more expensive to produce than Dynamic RAM and as a result is not suitable for use as main
memory in a computer.

When the processor wants to read from a memory location, it first checks the cache for the
location. If the location is in the cache, the processor can access the data without accessing main
memory - the location is accessed at the speed of the processor. This is called a cache hit. If the
location is not in the cache, then main memory must be accessed at the slower speed and this is
called a cache miss.

This small cache memory (typically 128KB) is called Level 1 cache (L1) and is on the processor.
A second cache called Level 2 cache (L2) is situated on the motherboard near the processor and
can be from 1MB to 8MB in size. This cache is slower than level 1 cache but still much faster
than main memory.

If a processor requires data from a location in RAM, the level 1 cache will be searched first. If the
location is not in level 1 cache, level 2 cache will be searched. Only if the location is not in level 2
cache must the slow main memory be accessed.

Modern computer systems have cache hit rates in excess on 90% and this has a huge bearing on
the overall performance of the computer system.

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Computer Hardware Overview (Part-2)

Post by ALI RAZA » Wed Oct 10, 2018 12:22 pm

The Motherboard

Often called the main board or system board, it is the main circuit board for the computer system
Every device in the computer system will either be part of the motherboard or connected to it.


The motherboard shown above is an Asus A8V-VM. This board is designed for AMD processors.
The main parts of the motherboard are:
1 Processor socket
This socket is an AMD 939 pin socket. It is designed for the
Athlon X2 processor. Different processors require different
sockets and a motherboard must be chosen to suit the
processor intended for use.
2 Memory sockets
The board has four memory sockets and accepts DDR
266/333/400MHz memory up to a total of 4GB
3 Power connector
The power supply connects here and supplies appropriate
power to the different components on the motherboard.
4 Primary IDE
Hard drives can be either IDE (Integrated Drive Electronics)
or SATA (Serial Advanced Technology Attachment). If an
IDE hard drive is being used, it should connect to this socket.
5 Secondary IDE
This could be used to connect a second IDE drive. This
could be a second hard drive or an Optical drive - DVD or CD drive.
6 CMOS RAM chip
A DRAM chip used to store the date and time and any user
settings added to the setup screen. Complementary metal
oxide semiconductor is the material the chip is made from.
7 CMOS battery
Because the CMOS chip is a DRAM chip, it is volatile and
would loose data when the computer is switched off. The
battery preserves the data in the CMOS RAM chip when the
computer is powered down.
8 SATA connectors Used to connect SATA hard drives and optical drives
9 BIOS chip
Basic Input/Output System. A chip holding the start-up
routine for the computer system. It runs a program to test
the hardware of the system. It the test is successful, a single
beep is sounded. If not, a series of beeps are sounded and
these beep patterns can be used to identify the failing component.
10 South bridge chip
Forms the chipset with the northbridge. Between them they
control the buses on the motherboard. Buses are the data
pathways between the motherboard components. The
southbridge controls the slower buses like the IDE bus,
SATA bus, USB bus etc.
11 North bridge chip
Controls the faster buses on the motherboard. These
include the front side bus (between the processor and main
memory) and the graphics bus.
12 PCI sockets
Peripheral Component Interconnect sockets used to connect
expansion cards like modems, network cards, TV tuner cards etc.
13 FDD connector For connecting a floppy disk drive.
14 PCI-Express
The graphics card connects here. Other motherboards have
an AGP (accelerated graphics port) slot.
15 Super I/O chip
Controls the serial, parallel, mouse and keyboard ports at
the back of the computer system.
16 Network chip Controls the network port at the back of the computer
17 Audio ports For connecting speakers, microphones etc.
18 USB ports The current standard for connecting peripherals.
19 Network port Used to connect the computer to a network
20 Video port
Connect the monitor to this port if a PCI-Express graphics
card is not being used.
21 Parallel port Largely obsolete. Used to connect printers and scanners.
22 Serial port Largely obsolete. Used to connect external modem etc.
23 PS2 ports
The keyboard connects to the purple port and the mouse
connects to the green port. Largely replaced by USB.
24 Audio chip Controls the on board audio system.

Chip set

The flow of data around the computer is controlled by the Chip set. This consists of two chips:

• North bridge: This chip controls the flow of data between memory and the
processor. It also controls the flow of data between the processor and
the graphic's card.
• South bridge: This chip controls the flow of data to the slower devices. These
include USB, IDE, SATA, LAN and Audio devices. It controls the
PCI slots and the on board graphics chip. It delegates control of the
keyboard, mouse, parallel and serial ports to the Super I/O chip.



A bus is a set of wires through which data can be sent to the different parts of the computer
system. Buses connect the major computer derives to each other. The chipset uses the buses to
send data around the motherboard. The main buses are:

• Front side bus: Connects the processor to the northbridge.
• Memory bus: Connects the northbridge to the main memory.
• Graphics bus: Connects the northbridge to the PCI-Express or AGP graphics
• Internal bus: Connects the northbridge to the southbridge
• PCI bus: Connects the PCI slots and the onboard graphics to the
• LPC bus: Connects low bandwidth devices to the southbridge. These
include the BIOS chip and the Super I/O chip which controls
the keyboard, mouse, parallel, serial ports etc.

Motherboards are processor specific. The main types available are:

• Socket 478: Intel Pentium IV processors
• Socket 775: Intel Dual Core and Core Duo processors
• Socket 754: AMD Athlon processors
• Socket 939: AMD Athlon 64 processors
• Socket AM2: AMD Athlon X2 processors

The Power Supply

The power supply can be seen from the back of the system unit. The mains cable is plugged into
the power supply. A computer power supply has a number of functions:

• It converts the power from Alternating current (AC) as supplied by the electric
supplier to Direct current (DC) as required by the computer system.
• It transforms the 240 Volts supplied by the electric supplier into the voltages required
by the computer system. The main voltages are:

• 12 volts for the disk drives as they have motors
• 3.3 and 5 volts for the circuit boards in the computer.

• It uses advances power management (APM) to allow the computer go into a standby
• Some have a switch to toggle between 240 volt supplies and 110 volt supplies.
The power supple has a number of connectors to connect to the motherboard, drives etc. The main
connectors are:
1 Main connector
Connects to the motherboard and supplies the 3.3 and 5 volt
supply for the board.
2 Molex connector Connects IDE hard drives and optical drives.
3 Berg connector Connects floppy disk drives
4 SATA connector Connects SATA drives

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Re: Computer Hardware Overview (Part-2)

Post by Ifra_Khan » Thu Oct 18, 2018 1:11 pm

Thanks This is Very Informative .... :geek:

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Re: Computer Hardware Overview (Part-2)

Post by Hiba Malik » Thu Oct 18, 2018 1:21 pm

bhot ala post thanks keep it up :idea:

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Re: Computer Hardware Overview (Part-2)

Post by ALI RAZA » Thu Oct 18, 2018 2:31 pm

Thanks For Appreciating My Posts :cry: :cry: :cry:

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Re: Computer Hardware Overview (Part-2)

Post by Princes_Noor » Tue Dec 18, 2018 7:02 pm

Thanku :oops:

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