Understanding CMOST and Bios Settings

You may have noticed when you start your computer, just before the operating system loads, there will be some data displayed, if you blink you will most likely miss it. What you are seeing is a small program the computer uses during startup. BIOS (Basic Input/Output System) contain a program to support simple hardware functions like keyboard, serial ports and speakers. Memory for functions that support time, date, power settings, hard drives and other devices are also stored in a ROM (Read Only Memory) on the motherboard called CMOS (Complimentary Metal-Oxide Semiconductor). CMOS is stored in a ROM chip and is utilized during start up. So again, as you have noticed countless times, the data you see just before your operating system loads, is CMOS and BIOS at work loading basic start up functions, it runs a basic memory check, checking for disk drives, peripherals, needed startup functions. This is BIOS in action. Here is a quick description of what is actually happening when you first load your system. First depress the power button and the system boots, BIOS runs it's built in program using information held in the special memory called CMOS. CMOS is kept alive when the battery is off by the CMOS battery. The CMOS battery is larger than a nickel and smaller than a quarter and is mounted on the motherboard. The CMOS battery is charged when the computer is on and slowly dissipates when the computer is off. A flat or dead CMOS can cause noticeable problems to a system, like the inability to keep the correct time and date or failing to load some drivers. Replacing a depleted or dead CMOS is a simple process.

Start by powering down the machine and then remove the cover or tower housing, remove the old battery and insert the new one, you are all done. Changing the CMOS battery may cause some systems to lose CMOS settings. Before changing the battery access BIOS/CMOS and take note of these settings in the case there is a need to restore them. Now let us access BIOS/CMOS settings and take a look around Start or restart your computer in the first few seconds you will see some text on the screen. The display will show the name of the BIOS manufacturer and the date the BIOS were made. There is usually a screen telling which keys to press. To enter the setup utility, the most common is the delete button, but don't panic, other keys are sometimes used, like F2. At first it will take some timing to correctly access. The information is only on the screen for a few seconds, it flashes and then the operating system loads. If your timing is off and you miss this small window of opportunity, simply restart your computer and give it another try. If you successfully access the CMOS/BIOS setting you will find yourself in the setup program. The user interface will vary from one manufacturer to the next, so they may not all be set up the same. Some basic features you may see that are usually constant are Save and Exit, Exit Without Saving, and Standard Features. Standard features deal with the likes of time, date, size of disk, and floppy drive. Advanced Features deals with enabling virus warnings, secondary boot devices. Make a note of these settings in the event of a flat or dead battery If you make changes be sure to save them so the system remembers them or simply hit exit without saving, this will leave the original setting in place. Windows has no options to back-up the CMOS settings. Exploring the BIOS/CMOS setting is an excellent way to familiarize yourself with the inner workings of your computer.