What do u mean BIOS with repect to computers?

Question

i know it is something associated with the computer basic component AND how does it work when the system is

1)starting

2)running i.e. in use and the hard disk and the processor is working

3)shutting down

4)when at stand by

5)when system is hibernated

Answer 1

its the motherboard firmware in short when you boot computer it boots into bios then the os

Answer 2

BIOS stands for Basic Input Output System.

The BIOS is created by a motherboard or hardware manufacturer. The BIOS is what starts the computer after you turn on the power to your computer. Software programs, such as the Windows operating system, work with the BIOS to make your computer more user friendly.

BIOS is the program that guides a PC through its startup routine. The typical BIOS consists of a set of simple instructions that are written on a flash ROM (read-only memory; an area of solid-state data storage) chip during production (post-production modifications are possible with BIOS updating software). The chip resides on the motherboard, near the processor. From this vantage point, the BIOS is able to facilitate the initial communication between the system hardware and software that makes the hardware functional.

Since the OS has to be loaded onto the RAM ( Computer Memory ) to run a processes at a UI ( User Interface ) level which allows an end user the oppurtunity to perform the things like accessing application et al, someone has to do that job ( loading the OS into the RAM everytime a system boots up / wakes from hibernate / or standby ). BIOS does this job by saving all pre load instructions required to passed to CPU ( including loading the OS initial files, which is done by CPU using a top of the stack code execution )

Listed are some of the fields available in a typical BIOS

Main, Advanced, Peripheral Configuration, Drive Configuration, Floppy Configuration, Event Log Configuration, USB Configuration, Power, Boot

Function while starting :-

BIOS will save instructions to lead a base level check of all system devices ( processor, RAM, ports ( PS2, USB, parallel, firewire and VGA amoung others ), once done and verified it will pass the signal for CPU to execute that pre saved code to load the initial files for OS into the RAM and after a successful system boot it passes complete control to the OS and loses importance in a post boot environment. The whole process is called POST ( Power On Self Test )

Function while running

BIOS will play a role of an identifier and controller of devices in a booted/running system.

Function while shutting down

BIOS will check for any shared IRQs, IRQs assignment in real mode ( such as VGA ) any plug and play device or hardware which is not communicating with the hardware correctly before the shutdown process is complete.

Numerious issues can result in BIOS leaving the OS hanging on the shutdown screen.

http://support.microsoft.com/kb/238096

Function when in standby

Most of new BIOS will not have any settings hard coded in it and available for the end user to enable/disable standby as it would be handled by ACPI or ONnow from MS. However, while going into standby again the BIOS will check whether the devices and other hardware can go into a standby state or not, if the settings in the software do not match the settings in the BIOS, the system might have issues going into standby.

Function when the system is hibernated

It's essentially the same as everywhere else, IRQs assignment & or conflicts, device & hardware compatiblity and settings, along with the IRQs for devices in real mode are checked by the BIOS before allowing the RAM contents being written into the HDD.

Answer 3

the BIOS (basic input/output system) contains all the code required to control the keyboard, display screen, disk drives, serial communications, and a number of miscellaneous functions.

When you turn on your computer and the microprocessor tries to execute its first instruction, it has to get that instruction from somewhere. It cannot get it from the operating system because the operating system is located on a hard disk, and the microprocessor cannot get to it without some instructions that tell it how. The BIOS provides those instructions. - What this means is BIOS is basically more on the booting than anything else.

When you turn on your computer, the BIOS does several things. This is its usual sequence:

   1. Check the CMOS Setup for custom settings

   2. Load the interrupt handlers and device drivers

   3. Initialize registers and power management

   4. Perform the power-on self-test (POST)

   5. Display system settings

   6. Determine which devices are bootable

   7. Initiate the bootstrap sequence

Answer 4

BIOS is always active.  It is a miniature operating system.  It boots first, before the operating system (such as Windows, Linux, or Mac), does a self-check and any configurations necessary, then starts the loading of the operating system, giving control of the devices it has configured to the booting OS.  

It is written on a physical chip called the CMOS chip on the motherboard, and it is powered by a battery called the CMOS battery.  Removal of this battery, simply resets the BIOS to its default state.  

It can be entered by special keystrokes at the early part of a computer's boot up period, and is variably customizable by the user.  Some BIOS's need to be entered by setting a jumper on the motherboard, but that is not in much use today.  

Couple of online defs for BIOS:

Basic Input / Output System. The hard-wired instructions that the CPU uses to boot up and to control I/O devices.

www.m2ktech.com/hardware_glossary.htm

(Basic Input/Output System). Built-in software that contains the code required to control the keyboard, monitor, disk drives, communications ports, and other functions independently of the computer operating system.

www.ukorbit.com/computer-glossary.htm

Answer 5

BIOS in part refers to the firmware code run by a PC when first powered on, which is a type of boot loader. The primary function of the BIOS is to identify and initialize system component hardware (such as the video display card, hard disk, and floppy). This is to prepare the machine into a known low capability state, so other software programs stored on various media can load, execute, and assume control of the PC.

For further details look in the source.