BIOS is a small chip on motherboard on which we can load software onto
which is called firmware that controls single pc hardware known as BIOS.
It provides the programming
that enables the CPU to communicate with other hardware.
its boot sequence is in the
order of -Power good -> CPU-> POST ->boot
loader ->operating system.
BIOS is used to check the
hardware configuration before installing OS for the first time.
BIOS provides security to a
pc online through LOJAC software to prevent theft
BIOS allows us to set user
password and supervisor password to prevent misuse of pc and BIOS operation.
CMOS BATTERY AND BIOS CHIP
When you turn on the pc/computer POST(power on
self test) is performed by the BIOS first,which checks for different hardware
connected to the pc working properly or not(just like a man getting up from
comma and checking all his body parts working or not) then select OS and loads
basic configuration.
To know the BIOS version and type we use two commands DXDIAG and
MSINFO32. if you want to check bios setup utilites without
affecting your computer you can use microsoft virtual pc,vmware softwares.
When you are entering the below set up by pressing
keys such as f2,esc ,del etc.keys are diff. for diff. manufacturer during booting ,you are
entering the cmos not the BIOS setup.The BIOS cannot be updated by the user it
is done by manufacturer.CMOS stores the data we have modified in the setup. CMOS does not store
programs; it only stores data.BIOS reads instruction from cmos chip during
bootup process.
The interconnection between cpu and ram is done
through a chip known as chipsets(northbridge and south bridge).
The Northbridge(directly linked to
cpu) deals with high-speed interfaces such as the
connection to your video card and RAM.
The Southbridge(linked to i/o devices) works mainly with lower-speed devices
such as the keyboard, USB controller and hard drive controllers.
In the above diagram it shows how the
cpu interacts with keyboard:-
When we press a key on keyboard
scanner chip on keyboard scans the pressed key and provides the scanned code to
the 8042 keyboard controller chip.8042 chip loads the code on databus.The cpu
comes to know about the data on data bus with the help of BIOS instruction
stored on ROM chip.
