BIOS
is an acronym for Basic Input/Output System. It is the
boot firmware program on a PC, and controls the computer
from the time you start it up until the operating system
takes over. When you turn on a PC, the BIOS first conducts
a basic hardware check, called a Power-On Self Test (POST),
to determine whether all of the attachments are present
and working. Then it loads the operating system into your
computer's random access memory, or RAM.
The
BIOS also manages data flow between the computer's operating
system and attached devices such as the hard disk, video
card, keyboard, mouse, and printer.
The BIOS stores the date, time, and your system configuration
information in a battery-powered, non-volatile memory
chip, called a CMOS (Complementary Metal Oxide Semiconductor)
after its manufacturing process.
Although the BIOS is standardized and should rarely require
updating, some older BIOS chips may not accommodate new
hardware devices. Before the early 1990s, you couldn't
update the BIOS without removing and replacing its ROM
chip. Contemporary BIOS resides on memory chips such as
flash chips or EEPROM (Electrically Erasable Programmable
Read-Only Memory), so that you can update the BIOS yourself
if necessary.
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