About Bios Setup, To Run Bios Setup, About Cmos

Intel 945 Series	User's Manual

Chapter 4 BIOS Setup Utility

BIOS stands for Basic Input and Output System. It was once called ROM BIOS when it was stored in a Read-Only Memory (ROM) chip. Now manufacturers would like to store BIOS in EEPROM which means Electrically Erasable Programmable Memory. BIOS used in this series of mainboard is stored in EEPROM, and is the first program to run when you turn on your computer.

BIOS performs the following functions:

1.Initializing and testing hardware in your computer (a process called "POST", for Power On Self Test).

2.Loading and running your operating system.

3.Helping your operating system and application programs manage your PC hardware by means of a set of routines called BIOS Run-Time Service.

4.1 About BIOS Setup

BIOS Setup is an interactive BIOS program that you need to run when:

1.Changing the hardware of your system. (For example: installing a new Hard Disk etc.)

2.Modifying the behavior of your computer. (For example: changing the system time or date, or turning special features on or off etc.)

3.Enhancing your computer's behavior. (For example: speeding up performance by turning on shadowing or cache)

4.2To Run BIOS Setup

First access BIOS setup menu by pressing <DEL> key after “POST” is complete (before OS is loaded). BIOS will then display the following message:

DEL: SETUP

4.3 About CMOS

CMOS is the memory maintained by a battery. CMOS is used to store the BIOS settings you have selected in BIOS Setup. CMOS also maintains the internal clock. Every time you turn on your computer, the BIOS looks into CMOS for the settings you have selected and configures your computer accordingly. If the battery runs out of power, the CMOS data will be lost and POST will issue a “CMOS invalid” or “CMOS checksum invalid” message. If this happens, you have to replace the battery and check and configure the BIOS Setup for the new start.

4.4 The POST (Power On Self Test)

POST is an acronym for Power On Self Test. This program will test all things the BIOS does before the operating system is started. Each of POST routines is assigned a POST code, a unique number which is sent to I/O port 080h before the routine is executed.

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