An Essential Guide to Central Processing Unit Components

Central Processing is most essential component of computer and whenever we say CPU our basic mean is the Processor the brain of the CPU. But we know that there are many other components inside the CPU that work together inside to do the work that CPU does for a Computer. This guide will give short brief introduction to components inside the computer.

Before we move on it's better to give the list of essential components inside CPU and we'll discuss on each one-by-one but very short:

  • Motherboard or simply MOBO
  • Computer Chips
  • Microprocessor
  • Expansion Slots
  • Computer Memory or RAM Banks or Slots
  • CMOS Battery
  • Additional / Add-on Devices
  • Display Card
  • Sound Card
  • Modem
  • LAN Card
  • Peripheral Devices
  • Ports
  • Universal Serial Bus
  • Power Supply


Motherboard is a very large print circuit board (PCB) that is fixed inside of CPU. You'll find many kind components fixed on the motherboard and remember that without motherboard CPU there is no importance of CPU, it's just like considered as a metal casing and nothing else. Importance of Motherboard for a CPU is similar as the importance of CPU for a Computer. Every of the component attached to the motherboard can communicate with each other (e.g. Mouse click to play a sound, means mouse actually communicate with sound device to get this music playing task done).

Any motherboard consists of following components that are fixed to it:

i) Computer Chips

There is a set various kinds of ICs (Integrated circuits or Computer chips) inside any motherboard that work together to manage and control computer. In this set of IC's Microprocessor (CPU) and other chips are included that control the flow of data inside computer.

ii) Microprocessor

Microprocessor is an IC that is actually known as CPU. It does all kind of mathematical operations and processes every single instruction sent by input devices. Microprocessors gets the input from RAM to process it and then send all processed data to RAM again. That's the way microprocessor acts as a central part of the CPU casing.

It's a fact that the working speed of any computer (speed of data processing) depends upon the working speed of microprocessor chip attached to it. Every microprocessor has it's own model number and working speed or Clock-speed. Microprocessor's speed measures in Mega Hertz (MHz) or Giga Hertz (GHz). Every microprocessor today can able to process one or more tasks at a time.

iii) Expansion Slots

Those specific slots that allows you attach additional devices to your motherboard, and are known as Expansion Slots. We fix computer cards (PCB) into the

Expansion slots so that these cards immediately connected to the motherboard to work together with other devices. Basically purpose of expansion slots is to increase the capabilities of a computer a bit more or increase functionality of a computer (e.g. I want to play latest games then I definitely need a better graphics capabilities of computer so I need a better Graphics Card that will fit into the expansion slots to do the job I want).

There are various sizes of slots known such as 8-bit, 16-bit, 32-bit and 64-bit slot. Slots with bigger size means data communication between microprocessor and expansion card will be fast or in less time. There was a day when we've had only two types of slots ISA and PCI. ISA the 16-bit slot and PCI the 64-bit size slot.

But Today there are some new expansion slots are there are AGP and PCI Express. the PCI Express slot has become the most popular expansion slot today that communicates with processor more faster and efficiently. Unfortunately AGP slots are rare now because PCI express beat them so badly.

iv) Computer Memory or RAM Banks or Slots

RAM slots are the places where fix our RAM chips. RAM chips are used to store computer memory (in form of bits) temporarily that helps to keep the software running on to the computer. RAM is a primary data storage device and classed as volatile memory due to losing data after power off.


BIOS is an abbreviation of Basic Input Output System. BIOS is the most essential/important program of any computer that controls the computer hardware. it has stored the basic memory of a computer that contains information about the devices connected the computer. Whenever you power on the computer initially BIOS is the program that runs first and read setting of computer and POST (Power on Self-test) confirms these settings.

BIOS is a ROM chip that is usually fixed into motherboard permanently, this chip has the BIOS programs stored in it. If in any case BIOS program corrupts then your computer will become unusable. However, you can fix it but only after some hard efforts. ROM is a non-volatile memory.

vi) CMOS Battery
There is small battery fixed inside the motherboard which allows to keep store the most important information (e.g. Computer Date/Time) of a computer even when it's turned off. When you turn off the computer then this battery (CMOS chips) starts doing it's work to keep these information stored. CMOS is kind a small computer memory. As you turn on the computer then CMOS battery work finishes here.

vii) Additional / Add-on Devices:
Add-on devices are the devices that perform specific function into the computer that usually not available in your computer right now. But these are unnecessary to run a computer. However you may need such add-on devices to perform a specific the function for example display card to see output of computer, Listen sound with sound card. Add-on devices are physically in the form of a print circuit board that you fix into the Expansion slots.

Sometime a computer already have a built-in VGA port (Video graphics array) then you don't need have another expansion card for graphics device, but again you may need this run high-end application or game. We use various kinds of additional devices for example Graphics Card, Modem, LAN, etc. For this you've to buy the required card and place in any of available relevant slot.

Below we're discussing about some of important additional devices:

Display Card - You should know that to see display of any computer is not just depend on the monitor, but also you should have a display adapter (Graphic Adapter, Video Card, Video Controller) installed into the motherboard. It's the display adapter that shows the output of program running inside the computer on the monitor screen. It's possible that your computer have a built-in display adapter or video port however you can also install Display Adapter card into the expansion slots.

There are four types of graphics adapters: (i- Integrated - built-in to the motherboard, ii- PCI can only fix into PCI slot, iii- AGP - these slots are rare now, iv- PCI Express currently the most popular slot for graphic adapters). There are three common connectors: VGA, SVGA and DVI connectors, We'll discuss in brief in coming articles.

Sound Card -
Sound card is a print circuit board which converts the sound into binary codes the native computer language. When we send our sound to the computer with microphone then sound cards convert the sound into codes for processing in computer and after processing then convert the code into sound and send to the speakers as an output. Microphone and Speakers can be attached to sound card so we can record our voice , and play music as well.

Modem - Modems is an abbreviation of MOdulator / DEModulator convert the computer data into information to it through telephone wires from one place to another on the internet. Modem can allow long distance and short distance communication between computers. Usually whenever we fix Modem card into the motherboard and connect the telephone wires then you can get and use the facility of internet.

LAN Card - LAN (Local Area Network) is a such network by which we can connect together many computer and can send/receive data between these connected computers. You can get the advantage to use devices connected to the computer on the network, For example printing on a network computer. You can only able to make this network with the by using LAN card.

LAN card fixed into motherboard. If two computers have LAN card installed in it then you can create a network between these computers. Like Modem, LAN card cannot send/receive information on long-distance.

xii) Peripheral Devices

Peripheral devices are such devices without them computer can work, but are not essential to the computer. Usually, peripheral devices adds a new function to increase the capabilities of computer. Mouse and Keyboard are most essential peripheral devices. But, as input devices these devices are much important to any computer. Normally, peripheral devices connect the computer externally. Some examples of peripheral devices are, Mouse, Keyboard, Printer, Modem, Joystick, etc..

xiii) Ports

For every external device like Mouse, Keyboard, Modem, etc. there is a connection point available from motherboard to get these connected to the computer to send and receive data between computer and devices internally and externally. For example we connect Printer to 'Parallel port' of the computer this port is known as LPT port. We connect modem to serial port which is known as COM port.

xiv) Universal Serial Bus

These are the newly introduced ports and currently the most popular port for connecting any kind of peripheral like Keyboard, Mouse, Printer, Scanner and Camera etc. It's a thin connector, in past there was just one USB port but today new motherboards come with more USB ports with any other port. That's reason why Keyboard/Mouse Serial and PS/2 ports replaced with this powerful port. However If you want to increase number of USB ports you can do this placing card into the expansion slot.

One of the greatest advantage of the USB port is Operating System can able to detect any device attach to USB port automatically without installation of any driver most of the time or ask to install drivers if needed.

Power Supply:

Power supply is source give electric power to the computer. An average Power supply can be 220 volts AC (alternating current) or something that converts our home electricity into 3.3 or 5 volts DC (direct current) for motherboard it's devices and 12 volts DC for hard disk and motors). Today most of average power supplies start from 350 volts AC due to requirement of power from processors, and graphics card, etc..

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Please read the remaining parts of lesson 3 by clicking below:
2. How to Use Keyboard Step-by-Step Guide
3. Introduction a Computer Mouse

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