You must have seen your keyboard lights, optical mouse light, CD-ROM drive light, floppy drive light blink when you switch on your computer. Ever wondered what happens when you switch on your PC? Did you think the OS in your machine picked up control once you switched on? If you thought so then you are mistaken. Then who gets the control? It is a program that is burned into a ROM (Read Only Memory) chip. It is called BIOS - Basic Input Output System. The purpose of this program is to take an inventory of hardware that is available and working properly and to initialize these hardware devices. Once intialized it transfers some of these information into the Random Access Memory (RAM) to be used by the Operating System and other programs. Once done then it looks up which is the booting device, whether it is in floppy disk, or the hard disk or from the CD-ROM. The BIOS is configurable, when you switch on the machine and after the inventory check is done and your monitor comes alive, you would see a statement like “Press F1 for setup” or “Press DEL for setup”. I mean the key that you press to get into the BIOS configuration is dependent on the BIOS manufacturer and what key he captures to bring up that screen. Try this out and look at the various configuration options available in your computer. WARNING: Do not modify the settings unless you are aware of the impact of the change.