The Motherboard BIOS
The BIOS is short for Basic Input / Output System. By definition, it is the interface between software and hardware which allows software and hardware to communicate and interact with each other.
The BIOS actually comprises of everything that allows software and hardware to interact with each other. While you may think that the BIOS only exists in the form of the motherboard BIOS, it is actually the combination of the motherboard BIOS, the BIOS of all add-on cards in the system as well as their device drivers.
Although, by definition, the BIOS consists of the motherboard BIOS, the BIOS of all add-on cards in the system as well as their drivers, we will be concentrating on the motherboard BIOS in this guide.
The motherboard BIOS is the most important component of the BIOS layer. That is because it contains all the software that is needed to get the computer started. It also comes with basic diagnostics and utilities.
The BIOS Chip
The motherboard BIOS is stored in a chip on the motherboard. The BIOS chip normally comes in the form of a rectangular DIP (Dual In-line Package) or a square PLCC (Plastic Leaded Chip Carrier) package.
The capacity of BIOS chips is measured in Megabits. Most BIOS chips these days are 2Mbits (256KB) in size. These higher capacity chips allow the manufacturer to offer more features than is possible with the smaller 1Mbit chips.
But note that the size of the BIOS chip has nothing to do with its performance. The choice of type and size of the BIOS chip is a matter of economics and requirements.