Introduction
When faced with a computer for the first time, it may seem a daunting collection of incomprehensible and complex parts. In fact, because of the ease of use of modern computers, there is little that the basic user needs to know about the internal workings of the computer, as long as you have technical support for when the machine does go seriously wrong. What you do need to know is what the various constituent parts of the computer are and how they each contribute to the final product.

There is an important distinction between computer 'hardware' and 'software'. The hardware means the physical components of the computer itself, for example the monitor or the keyboard. The software is the programs which you run on a computer. They consist of a series of electronic instructions to the computer. A 'software application' is a pre-written software program such as a word-processor or spreadsheet.

Hardware
The components of the computer hardware are shown below:

In addition, the computer may have more than one floppy disk drive and a CD-ROM drive.

• VDU/monitor: the visual display unit is the screen which allows the computer to communicate visually. It is usually a colour monitor.
• CPU: the central processing unit. This is the most important part of the computer, containing the microprocessor chip and the computer memory.
• Keyboard: this is the means by which you input your information and give commands to the computer. It consists of a type-writer style section of letters, a numeric keypad (usually on the right hand side) and the function keys (F1, F2 etc.). These function keys have been assigned to perform specific tasks which may differ from one software application to another. Basically they function as short cuts for certain tasks. For example, in our word processing package (WORD), F7 performs a spell check on your text. In addition, combining certain keys will perform a specific task: in WORD, Ctrl+S (i.e. pressing S while holding down the control key) will save your document.
• Mouse: this is an alternative way of giving some commands to the computer. A pointer or arrow is displayed on the screen and moves around as you move the mouse on the desk. By putting the pointer in specific positions and clicking button on the mouse, you give commands to the computer. It is usually quicker and easier than the keyboard.
• Floppy disk drive: this is the slot into which you put your floppy disk. It enables the computer to store your work to your own disk which can then be removed. It is usually call the A: drive.
• Printer: the printer is connected to your computer and is the means by which you produce a paper copy of your work or results. There are several types of printer, varying in speed, expense and quality of results. Least expensive are 'dot matrix' printers which consist of a number of pins hitting the paper through a ribbon. The more pins the better the quality i.e. a 24-pin DM printer will produce a clearer result than a 9-pin DM printer. Inkjet printers produce a better and quieter result, but the best results come from a laser printer.

It is also possible to input data using a Scanner. This is a device that copies an image from, for example, a book and sends it to the computer where it is stored using software that can interpret the image. This process works best at the moment for images as the software needed to recognise text accurately, especially hand-written text, is not perfect. Once the image is on the computer the software will enable you to make alterations to the image in terms of size or colouring. Text can usually be transferred to a word-processing package.

Once you have used the keyboard or mouse to input your data, it must be stored. The computer itself has two types of memory. The RAM (Random access memory) is measured in 'bytes' and is the part of the memory which holds the operating system and any applications in use. The bigger the RAM, the more powerful the computer. In addition, the computer stores memory on disks. There are two types of disk: hard and floppy (fixed and removable).

Floppy disks in their earliest version were just that: floppy. They now come in hard cases for protection but are still referred to a floppy disks. The best type for you to use is a 3.5 inch double-sided high-density disk which can store the most information and is a convenient size. These disks need to be 'formatted' so that it can be read by your computer. Pre-formatted disks are now available, otherwise it is a simple process (see the instructions to week 2). Disks need to be handled with some care and not exposed to certain conditions; check the instructions when you buy them for advice.

The hard disk drive is contained in your computer and is usually called the C: or D: drive. It stores the software and data permanently so it is not lost when you switch off the machine. Other drive letters usually refer to computers linked together on a network.

The memory of a computer is measured in bytes, kilobytes, megabytes and gigabytes. Each byte can store one letter or number. 1,000 bytes is a kilobyte; 1,000 kilobytes is a megabyte; and 1,000 megabytes is a gigabyte. An average hard disk may be around 3 or 400 megabytes; a floppy disk (as above) will store 1.44 megabytes (MB), approximately 1,440,000 characters. Images and graphs will take up more space that straightforward text and you may find these filling up your floppy disks quite quickly.

CD-ROM is another method of storing data. The 'Compact Disc, Read-Only Memory' has a much greater capacity for storing information and is mainly used at the moment to provide large reference works or sources of information. Hence, you get information from rather than store it to a CD-ROM.

Software
These are programs which are run by the computer. They usually consist of a number of files which are loaded on to the computer and stored on the hard disk drive. There is a huge range of software available at the moment ranging from database management systems designed to help you organise recipes or family history to applications which control entire manufacturing processes.

In this unit we will restrict ourselves to three main software applications: word processing, spreadsheets and databases. Specifically, we will be using software designed by Microsoft, respectively: WORD for Windows 6.0; EXCEL 5.0; and ACCESS 2.0.

Moving between software applications
To move between one open software application and another (i.e. from here in NETSCAPE back to WINDOWS PROGRAM MANAGER) use the ALT+TAB keys, by which we mean hold down the ALT key and at the same time press the TAB key ONCE. The name of the nearest application appears in the middle of the screen. If this is the application you require, release the ALT key and you will transfer to that application. If you require a different open application do not release the ALT key but press the TAB key once more or until the title of the application you require appears in the middle of the screen. To recap: each successive round of ALT+TAB moves you sequentially through the open software applications.

Networks:
Computers which are not connected to any other PCs are called 'free-standing' or 'workstations'. A 'networked' computer is one of a number of PCs linked to a master computer called a 'server'. Through a networked computer you can access software applications which are common to all the computers in the network. You can also use software such as NETSCAPE to access the World-Wide Web.

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(c)R. Middleton 1997      Last Modified 29 June 1998.