Thats a good question.... First we need to know what a BIOS is.. BIOS forms part of the computers Basic Input Output operation... doesn't explain much.. so I'll try this.. a hardware by itself is useless (duh!!).. we have all these devices connected to each other (CPU, memory.. drives the video card, other cards, controllers... IO chips... blah... blah..).. but all by themselves they do nothing.. there needs to be some logic.. so we need some software that does that and thats the BIOS.. when you turn on the system the BIOSs job is to initialize all devices, check that the necessary devices are working, ascertain that there is no conflicts within the system.. enable the devices to be registered. and then start loading the operating system.. But why not leave this to the operating system.. the operating system lives on the harddisk.. which would no tbe initialised.. and would be in a state 'X' which is unknown.. all devices may be in their own states after a start and bios does the cleanup and initializes the states of the devices.. yes we can have the operating system live up there doing the job of the BIOS (Linux bios @ http://www.acl.lanl.gov/linuxbios/) for this the bios does some low level stuff.. (somewhat akin to the device driver.. ).. but if you add in custom cards, it wouldn't know how to do things... as BIOSes are written for more generalised devices.. the devices initialised by the BIOS are accessible through the software interrupts (13 disk, 9,16 -> keyboars, 10->video functions (did I get that right.. been a while since I've done some assembly)).. However each hardware is unique.. and offers additional capabilities and features.. also accessing the device everytime though software interrupts is a waste of time.. hence we need device drivers to do those things for us.. device drivers are loaded up by the operating system.. to take advantage of the additional capabilities of the hardware.. and well sometime you have device drivers to do a lot of other stuff.. ever wondered what happens when you type in 'echo "hello world" >/dev/null' ??) why is a device driver faster than the BIOS.. well for once device drivers do not use the BIOS.. can be optimised... and since they are written for custome hardwrae they do not need a whole lot of 'generalisation baggage'... long read.... quiet true.. :) cheers, Sharath <HR> <br><font size=2 face="sans-serif">hi all,</font> <br><font size=2 face="sans-serif"> this is a pretty basix qn. how exactly the BIOS functioning are different from the device driver's functionality, since both of them control the i/o devices. i have read somewhere that we can bypass the BIOS for speedier access to I/O devices. how it's done? </font> <br><font size=2 face="sans-serif">thankx for ur time. </font> <br><font size=2 face="sans-serif">-Prabhakar</font> <br><font size=2 face="sans-serif"> </font> -- Kernelnewbies: Help each other learn about the Linux kernel. Archive: http://mail.nl.linux.org/kernelnewbies/ FAQ: http://kernelnewbies.org/faq/ ===== -Sharath __________________________________________________ Do You Yahoo!? LAUNCH - Your Yahoo! Music Experience http://launch.yahoo.com -- Kernelnewbies: Help each other learn about the Linux kernel. Archive: http://mail.nl.linux.org/kernelnewbies/ FAQ: http://kernelnewbies.org/faq/
