Windows

very easy.

1.open your case, pop out the the battery that looks like a watch battery (about the size of a quater) then reinsert it and boot.

2. newer mobo's have a jumper setting on the mobo which will clear the BIOS data and password, find it in your manual and set the jumper to erase, then set it back to it's original state.

See the following site,there should be no spaces when cut and space of URL
http://www.dewassoc.com/support/bios/bios_password.htm

This is actually dependant on what system you are talking about. Answer1 works on nearly all of them, but not all. Some require positioning a jumper, rebooting the computer, and then resetting the jumper. Some require a few backflips and handstands.Others can not be bypassed. This all depends on the motherboard. The best way to know is to go to the manufacturer's website for model specific information.

All the answers so far given have merit! Find the Dime sized battery [you need not remove it], then look for a group of three jumper pins that have text some thing like "reset cmos", or "erase Cmos". When you find these jumper pins [they will be near that dime shaped Cmos Battery] you will be half way home! With you computer off, but still connected to the wall[to ensure a ground] move the jumper into the "reset Cmos position" and wait 15 seconds. Place the jumper back to it's original position, and start system...
Note: Try doing this at least twice.

do a search on the net for KillCMOS.place on bootable floppy and away you go.

I have the KillCMOS program if you want it. I recommended it to someone earlier. It is really for a last resort, but it is very effective.

rknrlkid@aol.com