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Easier question (BIOS/CMOS)

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#1 dopplegangerguy


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Posted 04 December 2008 - 04:25 PM

I have a thread going that no one is responding to (because I can't give enough details, I'm guessing, but GOD would it be awesome if someone could just give me some general info), regarding the death of my video card and the fact that the new one will not give a signal to my monitor either...grrr...but so a co-worker in IT told me to zap the BIOS (though I keep seeing that it actually zaps the CMOS, and I only really understand that BIOS is the OS for the chip or motherboard or something...not such a techie).

So the question is that about a year ago, I installed on the computer in question (a Dell Precision 650) a 500GB hard drive when the one in there kicked the bucket. THen when I tried to install windows, nothing would work...as it turned out, I needed an update for the BIOS that Dell had put out...so if I do this BIOS/CMOS/whatever it is ZAP, will it roll that back to pre-update? I'll still be doing it anyway, because I need to fix this thing, but I'm just wondering whether I should be prepared to find that update again- will the zap roll it back or just reset to factory defaults but not actually undo the update?

Please help.

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#2 Platypus


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Posted 04 December 2008 - 05:13 PM

You've understood basically right, the BIOS and the CMOS memory are two different (but related) things. The BIOS (Basic Input/Output System) sets up the motherboard hardware when the system boots up, and provides a set of little routines that programs can use (if they wish) to gain basic standard access to the hardware. Most programs (including Windows) ignore this part of the BIOS. The BIOS resides in its own Flash RAM or EEPROM chip.

The CMOS memory is part of the RTC (Real Time Clock), and is held permanently active by the backup battery. The BIOS stores its settings (eg boot order of drives) in the CMOS memory, so if this memory is "zapped" (cleared), the BIOS settings will revert to defaults. It doesn't affect the BIOS itself, so if your system's BIOS has been updated to a more recent version than it had when it left the factory, that will remain unchanged.
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