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Re: Bios disk read error help
Posted: Tue Oct 13, 2020 12:16 pm
by abstractmath
Actually, scratch my last post. It seems to be working now? I think I forgot to rebuild my project or something.
Re: Bios disk read error help
Posted: Tue Oct 13, 2020 12:22 pm
by abstractmath
Oh that's funny. I still can't read past 40 blocks, even with the BIOS extension.
Re: Bios disk read error help
Posted: Tue Oct 13, 2020 12:23 pm
by Octocontrabass
Does your disk have 40 blocks?
Re: Bios disk read error help
Posted: Tue Oct 13, 2020 12:26 pm
by abstractmath
I'm not entirely sure. How can I check?
Re: Bios disk read error help
Posted: Tue Oct 13, 2020 12:28 pm
by Octocontrabass
How big is one block?
How big is your disk?
How many blocks can fit in your disk?
Re: Bios disk read error help
Posted: Tue Oct 13, 2020 12:35 pm
by abstractmath
I. Do. Not. Know. I'm looking at int 13h on wikipedia and I do not know how to get that information. Do I use AH = 0x48 or is there something better suited to what I need to know???
Re: Bios disk read error help
Posted: Tue Oct 13, 2020 12:40 pm
by Octocontrabass
If you're reading a hard disk with INT 0x13, the block size is 512 bytes. The specifications allow for different block sizes, but in practice no BIOS supports it.
Re: Bios disk read error help
Posted: Tue Oct 13, 2020 12:45 pm
by abstractmath
Is there a way that I can specify a drive size in qemu? I think that might help a bit.
Re: Bios disk read error help
Posted: Tue Oct 13, 2020 12:46 pm
by Octocontrabass
Of course.
The drive size is determined by the size of the disk image you're using.
Re: Bios disk read error help
Posted: Tue Oct 13, 2020 12:51 pm
by abstractmath
Ohhhhh okay, now it's making sense. My entire image file is about 21K in size, and that would make sense that the drive size wouldn't be past 40 blocks since 40 * 512 = ~21K.