Bios Question

  NotVeryTechie 16:31 25 Mar 2008

Hi there

Where does the BIOS live? What I mean is, does it reside in the CPU or on the disk? If you have two operating systems on a computer, like Vista in one partition and XP in another, how does the computer boot with the correct BIOS?

  Kemistri 16:38 25 Mar 2008

It's on a chip on the mainboard.

  DieSse 17:25 25 Mar 2008

And it's on a chip on the mainboard, so that a computer, even with no software at all, can start up and enable you to load some software.

That used to be called "bootstrapping" - now abbreviated usually to "booting" - from the saying "to pull yourself up by you own bootstraps".

The BIOS is actually a program, which can operate the screen, keyboard, mouse etc - and read information from disk drives (all types). Otherwise the system could never get going at all.

The BIOS proram is in non-volatile memory on the chip, so that it stays there all the time, irrespective of power or not (even irrespective of the battery).

Part of the chip also holds settings that you change when you "go into the BIOS". These settings are maintained by system power or the battery, which is why they can get lost when the battery (eventually) runs down. There is a basic set of these settings (called the default) which are always there, help in the pre-programmed part of the BIOS.

The contents of the BIOS chip can be changed (known as BIOS updating) to correct errors of introduce new features.

The chip is sometimes referred to as CMOS - this is the technology used to manufacture the chip (Complementary Metal Oxide Silicon) - the BIOS (Basic Input Output Subsystem) is the program in the chip.

Without a BIOS, PCs as we know them are just lumps of hardware than can do nothing at all.

  NotVeryTechie 08:59 26 Mar 2008

Wow, thank you DieSse! Brilliant explanation. Following on from that - does that mean that the Bios is independent from the operating system? So if you run two operating systems on the computer (in two partitions) does this happen independently of the Bios? So it doesn't matter what OS you have, the Bios stays the same?

  DieSse 09:15 26 Mar 2008

"So it doesn't matter what OS you have, the Bios stays the same?"

Yes - the BIOS is part of the hardware. It's there before any software is installed, and is independant of it. Vista, XP, DOS, Linux, BSD, one you write yourself, several in different partitions - doesn't matter to the BIOS. The BIOS simply allows it all to get loaded and started.

  NotVeryTechie 11:19 26 Mar 2008

Thank you!!

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