Why can't my OS run off of my computer?

Garfield

I really hope this is the right spot to ask this question...

I'm writing my own operating system. And, I use a BIOS interrupt (0x13) that reads a sector off of a disk (in my case, a floppy) and loads that sector at a given address. Anyway, this works on all computers, except my one computer. And what I'm thinking is that this BIOS interrupt (0x13) isn't "known" or something to my BIOS. So, the computer just doesn't continue with execution on the code. I don't understand what is wrong. What is the problem? How can I fix it?

Thanks!

NickS · Posted: Thu Jun 27, 2002 3:05 pm Post subject:

If the BIOS does not support Int 13h at all, it should not boot a floppy disk. Take a look at the sample (hard drive) MBR code at this location for an example; the MBR requires the Int 13h code to exist. There must be some other factor involved.
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Garfield · Posted: Thu Jun 27, 2002 6:32 pm Post subject:

So what do you think could be causing my problem?

Thanks!

Rainbow · Posted: Thu Jun 27, 2002 7:03 pm Post subject:

Look for bugs in your code.
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Garfield · Posted: Fri Jun 28, 2002 1:58 am Post subject:

If it was my code, then it wouldn't work on ANY computer. It just doesn't work on my one computer...

NickS · Posted: Fri Jun 28, 2002 8:51 am Post subject:

Garfield · Posted: Fri Jun 28, 2002 1:48 pm Post subject:

I just pin-pointed what exactly is causing the problem, and it's not INT 13h. It's a simple divide! The line of code is:

div WORD [SectorsPerTrack]

Anyways, I don't know how much that means to you (I don't know if you know Assembly). I don't know why my one computer can't handle this divide...

NickS · Posted: Fri Jun 28, 2002 2:08 pm Post subject:

Rainbow · Posted: Fri Jun 28, 2002 5:42 pm Post subject:

Early Pentium had bug in FDIV. I think that there's a divide overflow - just like in Award BIOSes - 32GB and 64GB bugs.
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Garfield · Posted: Sat Jun 29, 2002 1:26 am Post subject:

Nope, AMD...