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Ok, I know a little bit about bios but not much, so I was wondering If I could make a bios prog that would like run before the OS boots up and if so how to go about it. (like what to learn to do it)
Also:
Does it matter what bios it is? (what company made it and ect.)
You mean your own bios?
http://www.linuxbios.org/
Or something that runs before the OS starts?
A hacked boot disc accompanied with some c++ would do the trick.
http://www.bootdisk.com/
Im pretty sure most here would be unable to really help you without some more information.
You want this program to run instead of the BIOS?
or after the BIOS has finished executing?
What do you want it to accomplish when it does run?
a little clarification would be in order here.
I would ASSUME he wants something that runs before the OS starts... That's actually a pretty good idea.. You could use an outside integrity checker to check your hard drives before the OS gets loaded.
I would use this program called bios wizard
http://peripherals.about.com/library.../aa052201a.htm
Yea, like a program that I could make the bios run before the OS runs.... I don't have anything in mind but I was wondering if it is possable becuse it could be usefull.... And I know C++ but thats the only lang.
if thats the case, then maybe writing the program to accomplish what he wants, and possibly install it to the boot sector so that it will run before any OS will?
and then after it completes, it can then call the OS's boot process...
Im not real sharp at programming, but wouldnt such a prgram need to be small?
If so, then maybe have it written in assembler....if you can actually find anyone that uses that anymore...
Or, he could put a link basically in the MBR and it would go to a small partition where the program was held, then after the program finished you could have a line or 30 towards the end that says go back to part w/e of the boot record.
See, I got lost in what ya'll where saying.... MBR and stuff.... yea I only know a little about bios.
MBR= Master Boot Record. If you have XP or 2k or 98 or anything, it has stuff written there that tells the computer where the OS is.
Oh ok, I have Windows ME In case that helps anyones responce....
and how would I put a link in the MBR?
Hell if I know... You would have to be a VERY good programmer (which I assume you are not) and use some sort of boot disk with your program on it that would allow you to write to the MBR...
Yea, Im not that good... I can make basic games but thats about it.... (like missle command and ect.) Any easyer ways?
This is what happens when you boot your PC:
Firstly, the BIOS is executed from a chip held on your motherboard.
This is a very basic, low level program, which checks out the hardware on your PC (memory, hard drives, other standard devices etc.). It has nothing whatsoever to do with your OS and will work in exactly the same way on linux as in Windows (or anything else, come to that!).
And, no you don't want to tamper with this, except perhaps to install an upgrade from your manufacturer to support new hardware.
Each BIOS uses its own unique code, and each mother board is designed to run a particular type of BIOS.
Next, assuming your PC is working, the BIOS will find your primary hard drive.
It then looks for a special part of the hard drive which is located at the very first part of your hard drive (Cylinder 0; Head 0; Sector 1) which is known as the MBR (master boot record).
This will execute a simple sequence of instructions to start to load your OS - when I say simple we are talking about 512 bytes here - the size of memory I had when I first started programming :D
So, yes, you do need to program this in assembler (x86 if you are using an Intel chip), but the way Windows and linux work is that the whole of the first cylinder (usually 32Kb) is not used, so your basic 512 byte program can link to code stored in this area, as they do.
This code can be written in C/C++, but you need to be very careful, as most system calls will not work, but anyway you'll end up with some binary code, which you can write to this part of the hard drive.
So when you boot, your BIOS loads the MBR, which in turn usually executes the rest of the code you have stored in Cylinder 0, which in Windows & linux presents you with a basic menu (if you choose to enable it), and then your system completes its boot.
Needless to say, if you get your code wrong, then your PC won't boot until you replace the MBR, together with the rest of the code stored in Cylinder 0.
How about this. What is the goal of the program you want to write?
Oh, Should have added that if you setup your BIOS to boot from a floppy first (which is normal setup), CD, even USB memory sticks, then it will treat them in exactly the same way as a HD, i.e. look for the very first piece of information stored on the device and take it from there.
This is an easy way to test things, as you leave your HD alone, and put the new code on your floppy or whatever, and see what happens when you boot from it ..
Plenty of utilities on the net which you can find via google which will let you setup a floppy to do this.