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CMOS (complementary metal oxide semiconductor) is a
special type of memory (64K) used to hold crucial system operation
information called the BIOS (basic input/output system). The instructions
it holds are permanently written to the chip. The CMOS needs very low
power to operate. It is recharged every time the computer is turned on.
Most modern boards do not use batteries. The time and date is kept by the
CMOS. The type of CMOS does not effect the performance of the system.
BIOS is a program that manages data flow between the
operating system and attached devices such as the clock, hard disk, ram,
video adapter, input/output devices and power management. It is an
integral part of your hardware. The BIOS is accessible to the
microprocessor on an erasable programmable read-only memory (EPROM) chip.
When you turn on your computer, the microprocessor passes control to the
BIOS program, which is always located at the same place on EPROM.
When BIOS boots up your computer, it first determines
whether all of the attachments are in place and operational and then it
loads the operating system. Some BIOS setting can be changed from inside
the operating system such as the time and date. The BIOS inside a personal
computer determines whether the date will handle the year 2000 correctly.
The three leading BIOS manufacturers are AWARD,
Phoenix and AMI
(American Megatrends). |
