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What is a computer?

A computer is an electronic device that allows you to process and store data (information).

Data is entered into the computer by using a variety of input devices eg keyboard, scanner, mouse.

Once entered, the data can then be processed eg to produce a report.

The information can then be made available on a variety of output devices eg computer screen, printer.

Data can also be stored (saved) for future use.

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Hardware Hardware refers to the

physical, electrical and electronic components of the computer – the things you can actually TOUCH.

eg Monitor, mouse, keyboard, electrical cables, boxes which house components

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Software

Microsoft Office Acrobat Reader Internet Explorer Microsoft Works Outlook Express MYOB

Software refers to the instructions or programs that make the computer work (intangible – you can’t actually TOUCH it).

Software tells the computer what to do.

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Peripheral Devices A peripheral device is a device that is

attached to the computer and which usually performs some input or output task eg printer, scanner, backup storage devices, external CD ROM drives.

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The Central Processing Unit

Every computer needs instructions to tell it what to do, ie it needs to be programmed and it needs data in order to have something upon which to work.

The Central Processing Unit (CPU) is a chip which directs the activities of the computer. Its job is to receive and carry out instructions millions of times every second.

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RAM - Random Access Memory

RAM contains the data that is currently being used. When you run a program on your computer, both the program (such as a word processor) and the data being input (your letter) are placed in RAM for fast access.

RAM is a temporary or ‘volatile’ storage area. It will hold data only as long as the computer is turned on. If the computer is turned off, or if there is a power failure, all the data stored in RAM is lost.

That is why it is important to always SAVE your data to a permanent storage device such as the hard disk (C:), floppy disk (A:) or a CD/R so that you can safely turn the computer off and retrieve the data at a later date.

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ROM – Read Only Memory

When a computer is first switched on it accesses instructions which are stored on a memory chip. This process is called Read Only Memory (ROM).

This means that the computer can access the instructions and use them but the instructions cannot be changed ie they can only be read and not over-written.

The ROM tells the computer to check what components have been installed (eg keyboard, mouse, etc) and to see if they are all working correctly.

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BYTES

Storage capacity is measured in bytes.

1 byte equals approximately 1 typed character

Kilobyte (kb) approx. 1000 bytes

Megabyte (mb) approx. 1 million bytes

Gigabyte (gb) approx 1,000 million bytes

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Permanent Storage

Most computers come with a floppy disk drive, CD/R and a hard disk drive built into them. All of these storage devices allow you to take data from RAM and save it as a file for future use.

The hard disk is a fixed disk which is installed inside the computer. Most hard disks today store between 40 to 200 Gb

The floppy disk has a much smaller storage capacity (1.44Mb) than the hard disk but has the advantage of being removable. Floppies are quite easily damaged and are being replaced by CD/R’s & DVD’s.

All computers now come with CD/R (recordable) drives (often called Burners). CD’s store data digitally and can hold as much as 700Kb.

DVD/R’s are becoming increasingly popular as their price decreases. They can store from 4.7Gb to 17Gb.

Flash/pen/jump/usb drives are very small, inexpensive, portable hard disks which are an excellent way to store data or move data between different computers & locations. They plug in to computer usb ports & vary in size from 128Mb to 2Gb.

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Working with filesA computer file is an electronic document. When a file is saved it needs to be correctly named.Every file name ends with a dot (.) followed by an extension of 3 letters. A file saved in MS Word will have an extension of .doc , an MS Excel file will have an extension of .xls , MS Powerpoint .ppt . After awhile you will become familiar with the various file extensions & recognised what programs files were created in.Windows operating system automatically puts the correct extension on a file for you so you must never put a dot (.) in a file name.File names can be up to 250 characters and can include – and _ but cannot include any of the following symbols / \ : * ? “” < > ‘’System files are those used by the computer and should never be renamed, deleted or altered. Some system file extensions are: com, exe, bat, dll, cfg.

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Acknowledgements Originally devised by Karyn Taylor – Teacher, Faculty of Access Education Property of Gold Coast Institute of TAFE

PO Box 5547, GCMC Bundall, 9726