The ICT Lounge
 
Section 1.2:
Components of a Computer System and Storage Devices
 
In this section we will look at the different components (parts) of a computer system.

You will see what role each component plays within the computer system. You will also get to understand the features of each component.

This section also briefly introduces the different forms of storage devices that we use to hold out data.

Learning objectives of this section:
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Know what a computer system is and be able to identify and describe the main components of a computer system.
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Understand what internal memory is and be able to describe the difference between RAM and ROM.
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Be able to identify and describe the difference between input devices, storage devices and backing storage.
Computer Components
Key Words:
Motherboard, CPU, RAM, ROM, BIOS, BUS Network, Hertz, Graphics Card, Peripheral, Volatile, Non-Volatile, Storage Device
Definition:
"All the different pieces of electrical hardware that join together to make up the complete computer system."
Examples of common Computer Hardware (components): (click images to zoom and retrieve more info)
Motherboard
CPU
RAM
BIOS (ROM)
Graphics Card
Peripherals
Storage Devices
NOTE:
We will look at storage devices in greater detail in a later unit.
What is a computer system?
Components form the complete computer system. A computer system is made up of 4 main types of components:
  • Input Devices (keyboard, mouse etc)
  • Output Devices (monitor, speakers etc)
  • Secondary Storage Devices (hard disk drive, CD/DVD drive etc)
  • Processor and Primary Storage Devices (cpu, RAM)
Features of Internal Hardware Computer Components
Internal computer components are designed to fit INSIDE the computer system and they all carry out important roles. We will discuss the following:
  • Motherboard (this does something with the data to make it useful information)
  • Processor (central processing unit)
  • Internal Memory (RAM and ROM)
  • Video Card (aka graphics card)
  • Sound Card
  • Internal Hard Disk Drive
Motherboard
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The motherboard is central to any computer system.

 
Examples:
Click image to zoom in and retrieve more information.
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All components plug into the motherboard either directly (straight into the circuit board) or indirectly (via USB ports).
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Once connected to the motherboard, the components can work together to form the computer system.
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Components communicate and send signals to each other via the BUS Network.
 
Processor (CPU / Central Processing Unit)
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The Central Processing Unit (CPU) is the brain of the computer.
Examples:
Click image to zoom in and retrieve more information.
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The CPU 'controls' what the computer does and is responsible for performing calculations and data processing. It also handles the movement of data to and from system memory.
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CPU's come in a variety of speeds which are known as 'clock rates'. Clock rates are measured in 'Hertz'. Generally, the faster the clock rate, the faster the performance of the computer.
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There are two main brands of CPU currently on the market... AMD and Intel:
 
Internal Memory (RAM and ROM)
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There are two types of internal memory - RAM and ROM.
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RAM and ROM are used to store computer data and this can be directly accessed by the CPU.
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RAM and ROM are sometimes referred to as 'Primary Storage'.
 

RAM (Random Access Memory)

  • RAM is used to temporarily store information that is currently in use by the computer. This can include anything from word documents to videos.

  • RAM can be read from and written to and so the information stored in RAM can change all the time (it depends what tasks you are using the computer for).

  • RAM is a fast memory. Data can be written to and read from RAM very quickly. RAM is generally measured in GB (Gigabytes).

  • RAM is Volatile Memory. This means that information stored in RAM is deleted as soon as the computer is turned off.
Examples:
Click image to zoom in and retrieve more information.
 
NOTE:
If you use up all of your RAM by opening too many programs at once you will notice that your computer becomes very slow.

 
  • The more RAM you have installed in your computer -- the faster it can perform. You can open and use more programs at the same time without slowing the computer down.
 
ROM (Read Only Memory)
  • ROM is used to permanently store instructions that tell the computer how to boot (start up). It also loads the operating system (e.g. Windows).

    These instructions are known as the BIOS (Basic input/output system) or the boot program.

  • Information stored in ROM is known as READ ONLY. This means that the contents of ROM cannot be altered or added to by the user.

  • ROM is fast memory. Data stored in ROM can be accessed and read very quickly.

  • ROM is Non-Volatile memory. This means that stored information is not lost when the computer loses power.

  • Other examples of ROM include:
    • DVD/CD ROMS bought in stores containing pre-recorded music and movie files. These are played back at home but cannot be altered.
    • ROM in printers which is used to store different font types.
Examples:
Click image to zoom in and retrieve more information.
 
NOTE:
The computer would not start-up without ROM Bios.
 

How to remember the difference between RAM and ROM.
 
RAM
ROM
1.
Contents are lost when the computer is turned off.
2.
Contents are not lost when the computer is turned off.
3.
Stores instructions that tell the computer how to start up.
4.
Stores data and programs currently in use.
5.
Your computer will perform faster with more of this.
6.
This cannot be written to (altered).. only read.
7.
Stands for Random Access Memory.
8.
Stands for Read Only Memory.
Video Card (aka graphics card)
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Graphics cards are hardware devices that plug into the motherboard and enables the computer to display images on the monitor.
Examples:
Click image to zoom in and retrieve more information.

 
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Graphics cards usually require the installation of software alongside the hardware. The software instructs the computer how to use the graphics card and also allows you to alter settings to change image quality and size.
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See below for an example of graphics card software allowing the user to alter various graphical settings:
Sound Card
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Sound cards are internal hardware devices that plug into the motherboard.
Examples:
Click image to zoom in and retrieve more information.
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A sound card's main function is to allow the computer system to produce sound but they also allow users to connect microphones in order to input sounds into the computer.

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Sound cards are also useful in the conversion of analogue data into digital and vice versa.

This topic is discussed in more detail in later units.

Storage Devices (secondary backing storage)
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Secondary storage devices are used to store data that is not instantly needed by the computer.
Examples:
Click image to zoom in and retrieve more information about INTERNAL STORAGE.
 
Click image to zoom in and retrieve more information about EXTERNAL STORAGE.
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Secondary storage devices permanently store data and programs for as long as we need. These devices are also used to back-up data in case original copies are lost or damaged.
Remember:
Temporary storage like RAM does not hold data for long periods.

It is used to store only those programs and files that we are currently working on.


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There are two categories of storage devices:

  • Internal Storage - Internal Hard Disk Drives
  • External Storage - External Hard Disk Drive, Memory Stick etc
Example of how a hard disk drive works:

The video to the right shows how data is read/written to the hard disk drive by spinning a platter across a read/write head.

The read/write head is on the end of a movable arm.


Features of External Hardware Computer Components
External computer components connect to a computer system from OUTSIDE. They are not necessary for the system to function but make our experiences easier or better. We will discuss the following:
  • Input Devices (used to get data into a computer)
  • Output Devices (used to get information out of a computer)
  • Peripherals
Input Devices
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Input devices are pieces of hardware that get raw data into the computer ready for processing.

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Processing involves taking raw data and turning it into more useful information.
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Input devices fall into two categories:

  • Manual Input Devices - Need to be operated by a human to input information
  • Automatic Input Devices - Can input information on their own.
Manual Input Devices
Keyboard
Mouse
Microphone
Scanner
Numeric Keypad
Light Pen
Touch screen
Digital Camera
Web Cam
 
Automatic Input Devices
Magnetic Stripe Reader
Magnetic Ink Character Recognition
Chip and Pin Reader
Optical Mark Reader
Optical Character Reader
Barcode Reader
NOTE:
We will look at input devices in more detail during a later unit!
Click here to jump to the unit
   
Output Devices
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When inputted raw data has been processed it becomes usable information. Output devices are pieces of hardware that send this usable information out of the computer.
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Some output devices send information out temporarily and some send information out permanently:

  • Temporary Output Devices - E.g. Monitors which constantly refresh the outputted image on the screen
  • Permanent Output Devices - E.g. Printers which output information onto paper as a hard copy.
 
Output Devices
CRT Monitor
TFT Monitor
Laser Printer
Inkjet Printer
Dot Matrix Printer
Plotter
Speakers
Multimedia Projector

Note:
We will look at output devices in more detail during a later unit!

 
Peripheral Devices
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Almost all input and output devices are known as 'Peripheral devices'.
Examples:
Click image to zoom in and retrieve more information.
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These are 'non-essential' hardware components that usually connect to the system externally.
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Peripherals are called non-essential because the system can operate without them.

For example :
You can still use your computer without speakers... you will just have to do without high quality sound.


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Examples of peripherals are shown below:
 
Peripheral Devices
Keyboard
Mouse
Microphone
Web Cam
Scanner
Joystick
Speakers
Printer
 
Activity!

Click the above task and complete the diagram of a computer system.
Activity!

Click the above task and follow the instructions given on the sheet.
Activity!

Click the above task and arrange the components into the correct place on the motherboard.