[ The PC Guide | Systems and Components Reference Guide ]

Motherboard and System Devices

The motherboard is, in many ways, the most important component in your computer (not the processor, even though the processor gets much more attention.) As mentioned in the Overview, if the processor is the brain of the computer, then the motherboard and its major components (the chipset, BIOS, cache, etc.) are the major systems that this brain uses to control the rest of the computer. Having a good understanding of how the motherboard and its contained subsystems works is probably the most critical part of getting a good understanding of how PCs work in general.

The motherboard plays an important role in the following important aspects of your computer system (notice how many there are here):

• Organization: In one way or another, everything is eventually connected to the motherboard. The way that the motherboard is designed and laid out dictates how the entire computer is going to be organized.
• Control: The motherboard contains the chipset and BIOS program, which between them control most of the data flow within the computer.
• Communication: Almost all communication between the PC and its peripherals, other PCs, and you, the user, goes through the motherboard.
• Processor Support: The motherboard dictates directly your choice of processor for use in the system.
• Peripheral Support: The motherboard determines, in large part, what types of peripherals you can use in your PC. For example, the type of video card your system will use (ISA, VLB, PCI) is dependent on what system buses your motherboard uses.
• Performance: The motherboard is a major determining factor in your system's performance, for two main reasons. First and foremost, the motherboard determines what types of processors, memory, system buses, and hard disk interface speed your system can have, and these components dictate directly your system's performance. Second, the quality of the motherboard circuitry and chipset themselves have an impact on performance.
• Upgradability: The capabilities of your motherboard dictate to what extent you will be able to upgrade your machine. For example, there are some motherboards that will accept regular Pentiums of up to 133 MHz speed only, while others will go to 200 MHz. Obviously, the second one will give you more room to upgrade if you are starting with a P133.

In this chapter of the Reference Guide are several large sections that deal with the various parts that make up a modern motherboard. Many people just consider all of these as part of the motherboard. Physically, the cache, BIOS chip and system buses are on the motherboard, but in terms of operation, I feel it makes more sense to discuss them as "separate but connected". In part this is because the actual location of some of these components could change without affecting their function much. Logically, they are all closely related.

Next: The Motherboard

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