BIOS:BASIC INPUT OUTPUT SYSTEM IN DEPTH

 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.