BIOS (Basic Input/Output System)
Okay, so what does that mean? Well, it's really the first program that yer puter loads and runs. The processor uses the BIOS to get the puter started after you turn it on. It is also used to manage the flow of data between the computer and any attached hardware such as the hard drive, video card, mouse, keyboard and even the printer.

Okay, So Where Is It?
Every puter has one and it is located on the motherboard or mainboard inside the puter's case. It is actually located on a chip called an EEPROM or Erasable Programmable Read-Only Memory chip or on a chip called Flash ROM. That's fancy talk for a chips that can be written to with special software. BIOS EEPROMs from the days of the 80386, 80486 and even some early Pentium's were not programmable by the user and actually had to be replaced if an upgrade was needed. Most all systems today use Flash ROM chips.

How Does It Work?
When you turn yer puter on, the processor passes control to the BIOS program. It begins by checking the hardware to make sure that everything is connected and operational. This is called POST or Power On Self Test. If the BIOS detects a problem, it will stop and either display a POST error on the screen or it will sound a series of beeps to indicate what component has failed the POST. These beeps are commonly called POST codes. Once the POST has completed, the BIOS loads a portion of the operating system into memory so the system can boot.

Once the puter is running, the BIOS' work is not done. It continues working, providing a means for the operating system to communicate to any attached input/output devices. It's kind of like a traffic cop directing where things should go.

One Powerful Chip
The BIOS is a powerful little chip. It is also used to configure and control the motherboard itself. Things such as the amount of power that the processor receives, the system clock speed, the type of hard drive interface, the drive boot sequence and system boot password are all a function of the BIOS.