What Do You Get in a PC?

Operating System

This is the software that controls the basic operation of a computer. A typical operating system controls the peripheral devices such as printers, organizes the filing system, provides a means of communicating with the operator, and runs other programs.

Central Processing Unit

The central processing unit (CPU), often called a processor, is the heart of any PC. Essentially it controls how fast applications run. Processors are classified in three ways:

• By manufacturer, of which Intel is the most common. Intel is the market leader, but rival AMD offers processors that are fully compatible with Intel chips and are often cheaper and faster.
• With a description of the processor's class. The class is generally either a name or a number describing the level of advancement. For example, an Intel Pentium 4 is the fourth version of the Pentium-class chips and will have more features than a Pentium 3. However, some of the features of the Pentium 4 may not be relevant for home users or may work only with very specific applications.
• With a speed rating measured in megahertz (MHz) or gigahertz (GHz). This is similar to the litre rating on a car engine. A 1.1 litre Vauxhall Metro has less horsepower than a 2.4 litre Volvo estate. In the same way, an Intel Pentium 3 650 MHz processor has less power than an Intel Pentium 3 running at 850 MHz. The gigahertz rating means that the unit is measured in thousands, so an Intel Pentium 4 runs at 1.8 GHz (1800 MHz).

The speed of the processor is not the same as the speed of the PC because, like a car, the PC is the sum of all its parts. A fast CPU will be hampered if the rest of the PC is unable to keep up with the speed and performance of the processor.

Hard Disk

The hard disk drive is used to store all your software and files. There are two main criteria for hard disks.

• Type - normally either SCSI or IDE. SCSI is only used where speed is of the essence, such as high-performance servers, and is not normally found in home PCs. IDE is found in over 90% of home PCs.
• Storage capacity - this is measured in gigabytes (GB). Typically even the largest games or applications will not use more than 1GB of hard disk storage. Most hard disks will start at 40GB but if you're on a tight budget, even an 8 GB hard disk will allow for plenty of applications to be installed on your PC. If you are running out of hard disk space, provided you have the original CD-ROM disk that installed your software, you can always remove software from your hard disk and reinstall it as required.

RAM Memory

Random access memory (RAM) is used by the PC to execute applications. A simple rule of thumb is the more the merrier. RAM is measured in megabytes (MB) and most applications will need at least 64 MB of memory, but with memory prices dropping constantly, software developers are making their programs more memory-hungry. One word of caution - when buying a secondhand PC, it's wise to make sure that the PC uses the more modern type of DIMM memory, which is easily available, and not older SIMM memory modules, which are increasingly scarce and offer slower performance than DIMM.

Graphics Card

Computer games are the fastest-growing entertainment form. Consequently, the variety of graphics cards for the PC is huge. Graphics card manufacturers are constantly trying to outdo each other and the top of the pack changes weekly. A general rule of thumb is that graphics cards with a lot of memory will often provide good performance. If you're keen to experience fast action games, look at graphics cards costing around £200 from manufacturers such as Nvidia, S3, and ATI. These have the equivalent power of a dedicated games console such as a Sony Playstation 2 or Nintendo Gamecube.

CD-ROM / DVD Drives

Most new PCs are supplied with a DVD-ROM drive which will allow you to access conventional software and music CDs as well as DVD films. A more common feature now is the ability to write your own CDs or, on more advanced machines, you can create your own DVDs. You can use the CD/DVD-writer to create your own video disks, music collections, or digital pictures, or even to back up your important files.

Both the software and music industries are concerned about piracy and, consequently, using a CD/DVD-writer to make duplicates of copyrighted material is illegal and often difficult to do because of special anticopying features on video, software, and music disks.

Monitor

Monitors comes in two basic designs: a thin LCD, a bit like a laptop screen, or a traditional CRT which is similar to a small TV. LCD displays are great for saving space but can be three times the price of traditional PC displays. All displays come in various sizes, measured diagonally across the screen.