Building your own PC - Part 5

ISA & PCI Slots

On modern motherboards, there will be two types of slots available, usually split 4 PCI and 3 ISA. ISA slots are the older 16 (or a half-16 bit slot for 8 bit devices). ISA slots can be used for devices where speed is not so critical (such as printer ports) and are rapidly going out of fashion.

The newer PCI slots mean 32 bit processing of data with many PCI devices (such as graphic cards) having "local bus." This means that the card has its own processor to carry out specific tasks relative to the cards function. This additional processor then frees up the main CPU so that it can carry on with other tasks.

For example, a graphics card that has local bus will carry out the drawing of objects on its own rather than rely on the main CPU to tell it what to do. I guess it is the PC equivalent of "delegation"!

Graphic Cards

Graphic cards have come a long way since the early days of CGA and EGA (4 and 16 colours for those who don't remember). There are two main considerations and some others you might like to think about when building your own PC.

First is the amount of memory contained on the actual graphics card. This is NOT your computer's main memory; rather it is memory that is used only by the graphics card to process data. How much you need depends on what you use your computer for. Graphic-intensive processing such as CAD packages, graphics editing (including video titling) need larger amounts of memory than a word processor. Of course, games require the most. Your card should have a minimum of 4MB of memory with ideally 8MB. This makes sure that graphics "snap" into place rather than "plop" onto your screen.

The second main consideration is whether the card has 3D acceleration. If you are going to use the PC as a game machine then this is a must. The results with games that use 3D acceleration can be truly breathtaking, especially for games that use lots of polygons. Racing simulations for example employ this technique a great deal. I have played some games that fairly make your head spin when everything is drawn so smoothly with no jerking or judder. Those eerie, atmospheric games that have subdued lighting look fantastic too!

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