Functions of Computer Hardware Components

I work for an IT magazine company called ‘All Systems Go!’ The magazine reviews different computer systems, components and devices. My company has been approached by the producers of the TV programme The Gadget Show to write a blog or website to help their viewers understand the different elements of […]

I work for an IT magazine company called ‘All Systems Go!’ The magazine reviews different computer systems, components and devices. My company has been approached by the producers of the TV programme The Gadget Show to write a blog or website to help their viewers understand the different elements of a computer system. In this blog I will be covering computer system components and their different types of Internal System Units and Components such as Hard Drive, Configuration and Controllers, Ports, Internal Memory, Specialised Cards, Backing Storage and Peripherals.

The Internal System Unit is made up of many components such as the Processor, Motherboard, BIOS, Power supply, fan and heat sink, hard drive configuration and controllers e.g. RAM, ROM, Cache and specialised cards e.g. Network and graphic cards.


The processor is also known as the CPU which stands for Central Processing Unit and the Heart of the computer system which controls everything. The CPU is what functions most of your electronic products. What the CPU does is carry out most of the data processing by accepting input data and processing the data and then sending the information to the components that needs this information to carry out the action. In other words the CPU is what performs the commands and the CPU manages each command separately, even though the CPU is capable of processing multi commands in matter of seconds. This will all depend on how powerful your processor is because the more powerful it is, the faster your CPU can process commands.


How the Processor works?

If you double click on an icon to run a program, the program that is stored inside the hard disk drive will get transferred to the RAM Memory. Using a circuit called memory controller, the CPU loads the program data from the RAM memory. Once the CPU has loaded the program data it will then get processed inside of the CPU. What happens next totally depends on what instructions are inside the program, as a program is a series of instructions for the CPU. The processed data may have instructions inside the program which tell the CPU to display certain information on the screen such as opening up word processor or a game.

CPU Diagram

The diagram above shows how the CPU communicates with all the components on the motherboard. As you can see on the diagram, if the CPU wanted to communicate with any of the components it will have to go through the BUS in order to reach the component.


The Motherboard is the most important component in the system unit and the main function of the motherboard is to act as the main circuit board. The motherboard is what connects and communicates with all the devices and components that are attached to it. The necessary parts of the computer system and all connections between the computer system and the Peripheral go through the motherboard. The chipset that is on the motherboard directs the flow of data between a variety of buses that are connected with each components and the main purpose is to make sure the information reaches where it is supposed to.

The motherboard contains the CPU, PCI Slots, Graphic Cards, BIOS, memory, serial and parallel ports and also external connectors such as the keyboard and the mouse. The CPU which is responsible for taking commands and carrying out the action are not compatible with every motherboard but only certain motherboards. The PCI Slot also known as Peripheral Component Interconnect which allows the components to be placed directly onto the motherboard. The Graphics Cards is a device which takes the data and then converts it into information that can be read by you such as images so that this can be displayed on the computer monitor.

There are two chips on the motherboard which are known as South Bridge and North Bridge. The South Bridge and North Bridge are what manages what goes on within the computer and also helps the communication between multiple devices and chips. The North Bridge is responsible for communications between the CPU interface, the memory and many video processes, whereas, the South Bridge communicates with all the remaining devices. The North Bridge is directly connected with the CPU, RAM and graphic controller, so it acts as a bridge for the South Bridge chip to communicate with these components.



BIOS stand for Basic Input / Output System which allows the software and hardware to interact with one another. The BIOS is usually found on a ROM chip which comes with the computer and it is called the ROM BIOS. For starters let me explain what the BIOS do. The first thing that the BIOS do when you start your computer system is that it identifies all the system devices and makes sure that they are all in working order.

As the BIOS are on the ROM it is not affected by power failure and it also makes it possible for the computer to boot itself. So what the BIOS actually do is it boots up the PC such as starting up the computer system whenever it is turned On by the user. The BIOS then the actual hardware configurations are checked against the configuration data. It makes sure of the reliability of the computer system and proves to be the most important diagnostic tool available to you. The BIOS also allows the operating system to use particular features of hardware within the configuration by managing the input and output of the computer.

Bios communicate using a process called “POST”. POST is like a test that runs as soon as you start your Computer System. What the POST does is it checks that all your hardware is functioning as it is designed to, and this takes place before the BIOS starts to boot up. The POST test is so fast that sometimes we wouldn’t even realise it happened unless it detects a problem. If the POST test detects any faults then you will hear a beep sound and the computer system would stop without booting up.


Fan and Heat Sink or Cooling:

Heat sink is a device that is attached to the processor chip which serves a purpose to draw heat from the processor to make sure that the temperature of the processor is down. The heat sinks are made of an aluminium alloy and have fins to maximise the heat that is sucked in by the heat sink.

A Cooling Fan is a small fan that is fitted on to the heat sink to prevent it from overheating. So in other words most computer systems have a heat sink and a cooling fan together where they both work together to prevent components from overheating. So when the heat sink sucks in the heat, the air flow produced by the fan will lower the temperature of the heat sink in order to prevent it from overheating.

As certain components overheat it is necessary to have a heat sink and fan into to cool down the temperature of the components. It is important to prevent components overheating due to the fact that it can affect other components around it and that will those components around it will get damaged.

Fan and heat sink

The most commonly used type of Hard Disk Drive controllers are SATA, IDE can also be used but are not used a lot. The hard drive for a computer can be located within the processor box and they are IDE devices which are controlled by an IDE controller. There are two types of IDE controllers: Primary and Secondary. The hard drive will be attached to the primary IDE controller, whereas, a CD drive will be attached to a secondary channel on the motherboard. Each IDE ribbon that is connected to any one of these controllers can support two drives. Each drive will be identified as either the master or the slave drive in order to know which data relates to which drive. This allows both devices to communicate with one another such as by transferring data. If the Slave Drive wanted to transfer data it would have to communicate to the Master Drive and wait for a response whilst the Master Drive communicates with the computer and then the Slave Drive will get informed when it can transfer the data.

Master Drive: A Master Drive is what manages all the traffic on the IDE cable. A Master Drive’s controller saves its own data and passes on data to the slave drive.

Slave Drive: The Slave Drive can only see the data that has been passed on to it by the Master Drive. There will be no slave drive if there is only one drive connected to the cable.

Hard disk

The functions of ports are to allow peripheral devices to connect to the computer. There are a variety of ports that are found on the back of the system unit in order to connect a range of peripherals to connect to the processor. Two types of Ports can be found on the system unit: Serial Port and a Parallel Port.

Serial Port:  is an interface that can be used for serial communication. A Serial port only transmits 1 bit at a time and the cable is usually circular.

Parallel Port: Parallel Port allows the user to use devices side by side. Printers, USBs are all examples of peripherals that use Parallel Ports.

These ports are used to transfer data from a peripheral device to the computer. Serial communication is done through a transmitter which then sends data to a receiver using a single communication. These types of methods are really suitable for transferring or sending and receiving data over a long distance.

How do the ports on the System Unit look?


Internal Memory serves two main purposes: One is to store programs that are being run and other is to store the data that the program works on. Within the PC there are two types of memory: RAM and ROM.

RAM is also known as the Random Access Memory which is volatile and everything/applications that you have opened on your computer are what are stored in the RAM. RAM allows information to be stored and accessed quickly from random locations. All the programs and data will be transferred to the RAM from the Hard disk drive before it displayed on the screen for us to read.

As all the processing has to go through the CPU, it also requires the RAM to communicate with the CPU. The CPU will retrieve data from the RAM then it will send the information along to the data bus in order to reach the final destination such as the computer monitors which in an Output.


ROM is also known as Read-Only Memory which is non-volatile which is used to store small programs that cannot be altered or changed so basically it is permanently stored. ROM is mainly used to store the programs that are required to boot the computer. RAM is volatile memory so when the power is turned off everything is lost but ROM is non-volatile meaning that whatever is stored in it will remain even if the power is turned off.

How the ROM communicates is by sending instructions to the CPU in order to make sure that the hardware is correctly functioning in the way that they are supposed. Then the ROM will send instructions to the CPU to find the operating system of the computer. If the operating system is found then it will be loaded into the RAM in order for the RAM to take over the boot up process.


The main function of a Network card is to provide a physical link to a computer network which allows the computers to communicate with the servers. Each and every Network Interface Card has a unique serial number, which is called a MAC address. Every computer that is connected to a network has to have a unique MAC Address. How a Network card works is by sending an electrical or radio signals to each other using an agreed upon MAC protocol and network cards can either be wired or wireless.

Network card

The main function of a Graphics card is to allow computers to produce graphics and images quickly with better detail. The Graphics card has its own Processor called the GPU which accelerates the speed of the process. Usually graphics cards will have its own cooling  system as it heats up due to the amount of power it uses. The way Graphics card communicates is by sending data to the CPU on the motherboard. Then the data is sent to the graphics card where it gets converted into images and ready to be displayed on the monitor.

Graphics Card

Backing storage are backup devices which we use to save data and files on and these devices are external devices so which means that these are not inside of the system unit. These backup devices come in small sizes which means that they are portable. Examples of Backing Storage Devices are External Hard Drives, USB Pen Drives and Flash memory cards. These backup devices can be connected via USB ports on the system unit which makes it easier for files to be moved from one computer to another.

External Hard Drives are used as external storage space if your computer does not have enough memory to save your data or files. These External Hard Drives have a large storage space meaning that you can store as much data and files as you want. You do not need to worry about graphics files taking up much space as these hard drives have a large capacity.

External Hard drive

USB Pen drives are usually used to move data and files from one computer to another due to its small size and also as they have a low storage capacity. USB’s can also be used to save work that you have started on one computer then carry on with it on another computer. For example, if you start a Document at work and then want to continue with the document at home, you simply save it onto the USB. Then plug it into your home computer and you have access to the document at home.

SanDisk USB Flash Drive (U3)

Peripherals are Input and Output Devices which are external devices for your computer. Input Devices are external devices that can input data into your computer, whereas, Output devices output the data. Input Devices include Scanner and Keyboards. Output Devices include Printer and Monitor.

Keyboards: Keyboards are mostly used input devices as its required to type commands, letter or any software that requires you to type on. Keyboards have many keys with characters printed, each key represents a letter, number or symbol. Each and one of these keys have different functions of its own such as the A key types in the letter a.


Scanner: A scanner can be used to input data into the computer by scanning a document which can be edited using a OCR software. A scanner can also be used to scan pictures that you may want to add in emails, handouts or in a documentation.


Printer: A printer is an output device which is used to get a hard copy of data from the computer, you can do so by printing out a documentation or images. Printers are mostly used to print text, images and photos. People use a printer to print letters or invoices that they have already typed up on the computer, so that they can hand it to the end user.


Speaker: Speakers are an output device which are used to produce data such as sound mostly when connected to a computer. Speakers output sound that is generated by the computer. Speakers can also be used to listen to music which plays on your computer. The sound quality of speakers will depend on the watts for the speakers as computer speakers range widely in quality and price.



Concluding to everything that I have mentioned above I will advice that every component in the system unit are essential. Every component has its own unique role that it has to perform in order to make the computer function. You will need all of the components in the system unit to be working correctly in order to communicate with each other. Understanding each and every component can help to further understand how the computer system works. This can also lead to enhancing the components in the system unit to perform efficiently to meet your needs. For example, for gaming you may require a HD Graphics card.

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