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Understanding CMOS and the Pitfalls to Avoid

The role of the CMOS is to store the settings from the BIOS Setup program. When you build a system or modify hardware attached to the motherboard some changes may be required to be recorded in the BIOS. These include: time, date, drive and video parameters, memory, password, and much more. The contents of the CMOS memory is maintained for years by a small 3 - 6 volt battery which can be onboard or external to the motherboard. This page is focusing on one stored value, the BIOS password system and its removal. Frequently a hobbiests incounters a motherboard that will not boot up because of a stored CMOS password which is unknown or a user has forgotten. There are several ways to clear the password and other stored settings depending on the BIOS type ( AMI, AWARD, Pheonix, MR.BIOS....). Some clearing methods are simple while others require multiple reboots using secret keystrokes which we will collect and make available in the future.
The simplest method to clear the CMOS are:
1) remove or discharge the battery used to maintain these settings.
2) look for a jumper on your motherboard reserved for this purpose.
(NOTE - Some motherboards use a regulated capacitor discharge circuit to retain information while a person changes batteries, removeing the battery on these boards will not work unless the battery is removed and let to sit for up to a month or using a pair of insulated plier you short out the battery pins on the motherboard with a 10K ohm resistor for about 10-20 minutes AFTER! the battery is removed). There are also motherboards that store the information in a non-volatile memory chip which requires a set-up disk from the maker of the bios to reset the settings once the current ones are erased. There are motherboards & BIOS's where the above methods will not be effective which leads us to the existance of this webpage. As mentioned earlier other methods are available from some manufacturers but a 100% effective and POWERFULL! tool exists for handling this job. Be forwarned that this program is POWERFULL!, it will indeed remove all user settings from the CMOS including cache, drive, date, time, password, everything. It restores the CMOS to the factory settings. Unless you have a knowledge of using such a a program utilitiy it could be scarey and intimidating. Do not play with it unless you know exactly what you are doing, to remove the password is easy, but it will also remove all other settings, to go work beyond that point and reprogram the CMOS you have to have a working knowledge of EPROM's and binary code in hexadecimal format and the configuration codes used in setting up the base operating system of the motherboard. Use the program at your own risk and all responsibility is resting on yourself, no one can or will be held liable for damage incured by using this program, you have been warned, if you choose to use it the link is below, if not send me an email and we will see what other options are available for your circumstances, use this program as a

Note: Some CMOS's require a disk to reset the settings in the CMOS, make sure you have the setup disk before you attempt to change any settings or you may end up with problems. Contact the manufacturer of the motherboard or BIOS manufacturer for the setup program.

For more help go to the BIOS Page

Send further questions to:CMOS Help Desk