All motherboard must have special chip containing software called the ROM BIOS. This Rom Chip contains the startup programs and driver used to get the system running and act an interface to the basic hardware in the system.
The Bios is a collection of programs embedded in one or more chips, depending on the design of your computer that collection of programs is the first thing loaded when you start your computer even before the operating system. The Bios in most PCS has four main functions
POST: - (Power on Self Test)
Every PC has a built in ROM or Bios, which contains instructions to check the status of devices like memory, hard disk, Floppy drive, and CD- ROM Drive, keyboard, Serial Port and parallel port. When the PC is powered on. POST is executed and a system check is done to verify that all the sub-systems are working. Incase there are any hardware faults. POST intimates the same by giving beep sounds through the speaker present inside the PC or by displaying an error message on the monitor screen
SETUP: -
The system configuration and setup program is usually a menu driven program activated by pressing a special key during the POST, and it enables you to configure the motherboard and chipset setting along with the date and time passwords, disk derivers, and other basic system setting. We can also control the power management setting and boot drive sequence from the bios setup and also we can configure CPU timing and clock multiplier settings.
Boot Strap loader. :
A routine that reads the first physical sector of various disk drivers looking for a valid master boot record (MBR) if one meeting certain minimum criteria is found, the code within is executed. T MBR program codes then continue the boot process by reading the first physical sector of the bootable volume, which is the start of the volume boot record (VBR). The VBR then loads the first operating system startup file, which is usually IO.SYS (Dos/ Windows 9x, Me) or NTLDR (Windows NT / 2000/ XP) upon which the operating system is then in control and continues the boot process
BIOS: (Basic Input Output System)
This refers to the collection of actual drivers used to act as a basic interface between the operating system and hardware when the system is booted and running.
Plug & Play Systems (PNP)
Pug and Play is technology designed to prevent configuration problems and provide users with the capability to easily expand a PC with PNP the user simply plug in the new card and the system configures it automatically for proper operation.
For Plug and Play to work the following components are designed.
*PNP hardware
*PNP BIOS
*PNP operating System.