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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.
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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.
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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.
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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.
Click image to zoom in and retrieve more information about EXTERNAL STORAGE.
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Secondary storage devices permanently store dataand 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!
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'.
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