CMOS Vs. BIOS

The BIOS is modifiable. BIOS is an integral part of your computer and comes with it when you bring it home. The BIOS is a program that is made accessible to the microprocessor on an eraseable programmable read-only memory (EPROM) chip. When youturn on your computer, the microprocessor passes control to the BIOS program, which is always located at the same place on EPROM.

You can obtain from the manufacturer, BIOS upgrades in the form of "firmware" upgrades (software that is programmed to reprogram that chip). Because it is eraseable, it is changeable.

CMOS is a battery that maintains settings. BIOS is a program that is on an EPROM chip.

Basically the answer is no you can not change the bios setting, but in reality they can be changed by flashing the bios which can be done going to the web of the manufactuer and downloading the update. This is, in most cases put on a floppy and thenyou reboot and follow the instructions very carefully. Also there are viruses out which will flash your bios on boot crippleing your computer. There are some companies now that make it avilable to flash your bios and write the new updates while you are in windows. Gigabyte is one that does it at there web site, I don't know about others.

ok let me refrace the question.
is the BIOS where you change the IDE setting or the date and time?
can you access the BIOS and modify it your self?
I konw you can update your BIOS but can you access it by pressing del or F2 at boot up?
Y is people calling it the BIOS when they are actually refering to the CMOS, it got me mixed up for a sec.
So is it the CMOS or the BIOS?

The BIOS is a low-level program contained in EEPROM which executes at startup and handles things like POST, disk access, I/O and such through a collection of routines accessed via a series of interrupts.

Variable information needed by the BIOS to correctly interact with the hardware, such as the number of cylinders/tracks on the hard drives, special hardware settings and the like, is stored in a special chip implemented in CMOS for low-power operation. This allows this data to be preserved when power is off by a tiny battery on the motherboard. The values contained in the CMOS memory can be changed through the SETUP program at startup, and these values affect how the BIOS routines behave.

Incidentally, this CMOS chip usually (maybe always by now) also contains a RTC (Real Time Clock) circuit which is maintained by the same battery.

When the battery gets low, the CMOS can lose data, and the BIOS will then be relying on corrupted information. Erratic behavior, followed by total system failure, is usually caused by a dying or dead battery.

No that is not true inpart that you can use flashing to upgrade the Bios input/output instructions.
So,this would be a modification to the BIOS,the flashing changes the instructions of the BIOS.

There is correct, mis-guided, and outright wrong information posted throughtout the answers to this question.

The actual BIOS program on most PC motherboards, is stored in flash programmable memory.
That is why it is often referred to as "flashing the BIOS" when you upgrade the BIOS program.
(On some older pc's, the BIOS program is in a true ROM chip, and the only way to upgrade the BIOS is to replace the IC)

The variable or user BIOS settings that you set in the setup program are stored in a battery backed CMOS memory chip.

BIOS has become a slang term for the user settings for the MB. If you want to be technically correct, you should refer to the BIOS settings as the user settings.

The previous answer is correct. You can modify the BIOS by flashing it. An example is with Dell. Where I currently work we are constantly going to Dell's homepage and downloading the most recent update to disk. Simply pop in the disk, start the computer and by answering a couple of quick questions regarding making sure you want to update you will have the latest version. I have seen Dell's BIOS for the Optiplex go from A05 to A09 in something like 4 months.

Excuse me for my somewhat crass response, but this is a very anal thread, yet enjoyable to read all the same.
In short the BIOS is the program and the CMOS stores the user settings. Both BIOS and CMOS terms are often used incorrectly, but if you understand the basic premise then it really should not matter.

The CMOS chip (and battery combination) is on the motherboard that stores the BIOS. Therefore the terms are used almost interchangably.

Actually there are many chips on computer boards that are made with the CMOS process. But the one that holdsthe BIOS is the one called the CMOS.

BIOS is for the basic input/output settings or settings the computer needs regardless of operating system in order to run. They can be changed in as much as you have to tell the system what type of hard drive, serial port, LPT and the like you have on your system and (if done manually) configure the settings for those devices.

CMOS configures all the settings that basically interface with the operating system itself. System time, power management and the like.

A BIOS flash usually updates the IO device parameters so they may more effeciently operate with whatever motherboard they are configured to.

Both BIOS and CMOS are dependant upon one another. Over the years they have basically become synonymous because most vendors put the BIOS/CMOS information in the same place (you're F1, F2, etc...).