How do I set about buying a computer?

First of all let’s look at what is on the inside.

Power supply.

This transforms the mains 240 volts into several other voltages for use internally by the computer, usually varying between 3 and 24 Volts.

You do not usually get much choice in the matter when you buy a PC about how much capacity the power supply has. In the past some of the cheaper systems have had, what were perhaps, inadequate power supplies that have been unable to come with extra bits being added on to the system.

The Mother Board.

There is a large circuit board to which many other bits are attached.  This board is commonly known as the “Mother Board”. This board has the Central Processor Unit and immediately accessible memory plugged into it.

The Central Processor Unit – CPU.

People generally talk about how fast a CPU chip can process instructions. This is a fairly crude way to determine the potential performance of a system, and other parts of the system may have to also be quite quick to keep up with it. Systems that are designed to play games generally have very fast processors as lots of calculations have to be performed, rather than straightforward memory access.

In the past systems were able to perform instructions at so many megahertz. Systems now run at over 1 gigahertz. Generally now, you are looking to buy a system that runs at over 2 MHz. Either AMD or Intel might make the CPU. It probably does not matter.

Memory  (Immediate access) RAM – Random Access Memory

The more of this the better. Systems now need to have at the very least 128 Mega Bytes of memory. A Byte of memory holds an alphanumeric character, or a number in the range –128 to +127. 256Mb is better. 1024Mb is good, but more is nice to have as it can help to run things faster. This type of memory is much quicker to access that memory held on a hard disk drive.

Hard Disk Drive.

This holds the operating system, programs that manipulate data, and data.

In the past operating systems and programs only took up a small amount of space, counted in Mega Bytes. These things can now occupy several Gigabytes.

To be future proof a system should probably have at least a 70 GB hard drive, although half of that would probably be sufficient.

We will look at the operating system, and programs later.

A hard drive is actually several disks inside a metal case that spin very quickly. There are special "heads" that read and write information onto the disks. The heads are similar in concept to the arm on a record player. They move back and forth over the surface of the disks as they spin. They use magnetism to read and write binary information

Now let’s look at what is on the outside.

CD and DVD drives

These can be used to play music, and videos. They may also be used for the backing up of data on the Hard Disc Drive.

Monitor/Display.

These are now very much thinner than they used to be, as Liquid Crystal (LCD) technology is now used instead of the Cathode Ray Tube. A 19 inch one would be very nice to have, but smaller ones will suffice.

Keyboard and Mouse.

It is quite useful to have these as wireless devices, as it makes it much easer to locate them. Most keyboards are of the standard typewriter type layout. Many keyboards have extra keys to enable functions to be performs by using a single key press.

The mouse will come with a left and right button, and may also have a central wheel, that may be used to scroll through documents.

Printer.

For your hard copies. Printers are generally fairly cheap. Replacement ink cartridges are often quite expensive. It may be worth considering a photo’ quality printer for the slight extra expense.

Scanner.

This enables the reading of source documents, or for copying photographs etc.

Interactive Devices.

Web Cam.

Enables videos to be recoded, of for conversations with another computer user on the Internet.

Speakers and Microphone.

For playing and recoding, and may also be used for Internet conversations.

Modem

A “Modulator/Demodulator”. This converts signals from the computer to be sent down a telephone line, and vice versa. The more recent “Broadband” service is very quick.- At least ten times quicker than the old “Dial up” service. Broadband is generally more expensive, but is coming down in price. With the Dial up service, it is possible to pay for access to the Internet through the price of a local call. You will require a different modem, or connector for each type of service.

USB – Universal Serial Bus

These slots allow you to add on a variety of other devices.

Now for the Operating System and Programs

Microsoft Windows XP is the main operating system at present. Microsoft, and others produce programs to run on the Windows system. XP Professional is the best to get, but is does not matter that much if you are just a basic user.

There are other variations of Windows about, and other operating systems such as Unix and Linux. Most people plump for the Microsoft route.

Programs that you might want are:

• Word Processing: Typing letters, documents
• Browsing the internet – Sending and receiving internet mail
• Desk Top publishing (designing advertisements, brochures, leaflets etc)
• Graphic designing  (Architectural drawings, designing circuit boards)
• Database (lists of your video collection, business contacts)
• Spreadsheets (graphs and charts)  - Accounts
• Sending and receiving faxes
• Answerphone  service
• Working with images, pictures
• Educational: Using an encyclopaedia, other educational software
• Games:
• Playing music
• Playing DVD movies
• Video editing
• Connecting a musical instruments and making or editing music
• Reading or Writing CDs and DVDs
• Security: Connecting your computer to an office or other security system
• Scanning in documents for storage
• Web Site Designing

If you have an Internet connection, then it is also very necessary to have programs to protect you from other, perhaps malicious people on the Internet.

You will need a Firewall to keep others at arms length, and a Virus Scanner to protect you from any infections arriving from the Internet, or by e-mail.