Embedded Files
The Basic Input Output System (BIOS) is firmware (software stored in ROM) stored on a special memory chip on the motherboard.
The BIOS is a collection of programs used to control the following:
Input/Output from devices such as keyboard
Manages the boot sequence
Identifies and configures devices such as hard drives, optical drives, CPU, memory, floppy drives etc.
The image on the right shows the BIOS program which allows you to edit the configuration and user settings stored in the CMOS memory.
CMOS Memory
CMOS Memory
Complementary Metal Oxide Semiconductor. This is the technology used in the manufacture of microprocessors. CMOS in popular usage has come to mean the memory chip that stores the data that the BIOS needs for configuring the computer at startup. This memory, like normal RAM, needs power to keep its data. The chip only needs low levels of power so the data can be maintained by a small battery.
CMOS Battery - on the motherboard
The POST
The Power On Self Test is the very first stage of booting a computer. This routine runs diagnostic tests on the hardware like RAM, and peripheral devices as well as bus function. IF any part of the POST is failed the rest of the start up routine will not be executed. You will know when your computer had failed the POST because it will not boot and there will be a repeated beep that comes from the motherboards speaker. The frequency and interval of the beeps can be used to diagnose the reason for the failure. Some parts of the POST can be disabled, some cannot. Failure of the RAM or CPU integrity check will always cause a critical failure. Checks for keyboard or floppy disk presence are normally disabled because there are several ways of adding a keyboard and many computers run without any keyboard (For example servers, kiosk systems with a touch screen interface ...), and floppy disks are as rare as hens teeth. The purpose of the POST is to prevent a semi functional computer system from allowing the user to input data and then suffer loss of that data when the computer fails.
References:
References:
[1] Tim Fisher (n.d.) BIOS (Basic Input Output System) (Online) Available at: http://pcsupport.about.com/od/termsb/p/bios.htm (Accessed 15 August 2012)
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