Introduction to PC's BIOS
This chapter will introduce some basic knowledge about PC's BOIS, including what's the BIOS, where can you find it, and some BIOS working mechanism. the coming chapters will describe some basic setting for details, Bootbeta will tell you how to set and why.
What's the PC's BIOS?
BIOS(Basic Input-Output System) is a complete boot system, It posts some routines for basic issential haradware which are important for operating system's boot. BIOS's program has been burned in one ROM(EPROM or EEPROM), it includes some initial settings and basic POST(power-on selft test) when the PC is powered on. The BIOS information cannot lost even though the power is removed. Some bios settings are retained by the battery mounted on the motherboard. In fact, the basic BIOS will work OK even the battery is removed. but You may press F1 to continue or other tips.
Where can I find the BIOS?
When the computer start up, we can hear a beep from the motherboard's speaker, the speaker is install in your PC's box or plug in the motherboard directly. it often like a buzzer or a small speaker. If you hear several beeps when startup, I think your computer must suffered a problem. you should check the system hardware for something wrong. the computer can not start normally without fixing these issues.
The BIOS type may be finded by the booting screen,
Notes to Mac's user: Mac doesn't using BIOS loading, other knowledge, I will introduce them in the coming articles.
What's the BIOS's working mechanism?
When the computer is powered on. CPU will send control command to the bios while completing selft-test. The bios will finish POST of the computer and pass it's control to the priority operation system if it exists. The BIOS will test and verify the computer's hardware. Checking all the registed hardware are ready. If the BIOS find some problems, for example, one hardware not plug in properly, or memory is removed, etc. The BIOS will output proper beep tone.
There are so many main board manufactures, but there are quite a few for BIOS manufactures, At present, AMI,Award,VIA,etc. Award has been sold to Phoenix. Different BIOS manufatures may have different beep definitions. You can look for your PC's manual books for the details.
For more people, We should know what is corrected for BIOS's beep. that is a single short beep. I know some computers don't have the speaker accessory. so If you can't hear the beep. Your system may be OK,too.
What's the difference between BIOS and CMOS?
CMOS is a RW(read-write) RAM chip which has been pre-installed on the system board. I think CMOS and BIOS have equally position. but CMOS is completly controled by BIOS.
In summary,BIOS has some solid programs. but CMOS has active configuration. CMOS can give us a flexible setting for different systems. they are good friends. further more, CMOS will help to save clock refreshing. when we restart computer again, make sure the datetime be correct.
What will be happened if I remove the CMOS battery?
If the battery was removed, then the system clock status and some settings modified will be lost. for example, interrupt setting, some forbidden setting, etc. If you start the computer again, the computer will start from the BIOS basic settings. if so, for commonly, If the hardware has'nt been changed, the system booting will be OK, but some functions may be effected by the losing clock. because the datetime has go back to the pre-setting from manufacture factory. even thougn, You can refresh your clock from internet, but if the computer restart. clock information will be lost again until you install a good battery to the main board.
What will be happened if the CMOS battery has a low power?
If we use our computer for two year or more. the CMOS battery may have a low power, this will cause CMOS circuit working abnormality. the setting data may be lost. the clock should be unstable. all these phenomena may effect the operating system and software working properly. this time , we should change a new battery.
How can I change the BIOS settings?
Earlier, the BIOS programs are burned into a ROM, we can't update it flexibility, but now, almost all the mother board manufacturer burned the BIOS programs into EPROM, that mean we can update or upgrade it at anytime, (Note: some BIOS chip are fixed on the motherbord ,we cannot remove it early , but we can update it under Operating system OR common DOS, these upgrade programs may be find from the manufactures of the motherboard or the BIOS).
If you want to see or change some settings, you must not update or upgrade it, you should try to modify the BIOS setting through BIOS control panel. Fox example, we want to change the BIOS date time, or want to change the boot sequence in BIOS, etc. All of the first, you should know how to access and exit the BIOS? attention please, Look at your booting screen, the hotkey should be displayed . it may be DEL , F2,etc.
If we have finished changes, we can save them, If we find some problems about the new settings, we can modified it back or use the restoration function.