Motherboards also contain important computing components, such as the basic input/output system (BIOS), which contains the basic set of instructions required to control the computer when it is first turned on; different types of memory chips such as random access memory (RAM) and cache memory; mouse, keyboard, and monitor control circuitry; and logic chips that control various parts of the computer's function. Having as many of the key components of the computer as possible on the motherboard improves the speed and operation of the computer.
Users may expand their computer's capability by inserting an expansion board into special expansion slots on the motherboard. Expansion slots are standard with nearly all personal computers and offer faster speed, better graphics capabilities, communication capability with other computers, and audio and video capabilities. Expansion slots come in either half or full size, and can transfer 8 or 16 bits (the smallest units of information that a computer can process) at a time, respectively.
The pathways that carry data on the motherboard are called buses. The amount of data that can be transmitted at one time between a device, such as a printer or monitor, and the CPU affects the speed at which programs run. For this reason, buses are designed to carry as much data as possible. To work properly, expansion boards must conform to bus standards such as integrated drive electronics (IDE), Extended Industry Standard Architecture (EISA), or small computer system interface (SCSI).
