VBE function 0x4F0A

[Luis]

Hi,

I've tried Bochs, VMware and QEMU (with Bochs card, VMware card, QXL card and Cirrus card) and I can't make any of them work with function 0x4F0A. I can't even get a valid error code return in AH register (i get AX = 0x0A0D. They don't support that function or is there any trick to make it work?

PS: CX register is not mentioned in the function input description but if I don't 0 it I get the whole screen filled with music symbols after calling the interrupt.


Cheers,

Luís

[Luis]

I guess I found the problem is another. My code disassembled by NASM says 'mox ax, 0x4F0A' just like in my code but I see instead in Bochs debugger in the same place 'mov ax, 0x0A0D' followed by 'dec di'. Now I'm confused.

[MDenham]

Looking up "dec di" tells me that it's your missing 4F, which brings up the question of where the extra byte (the 0D) is coming from. My guess is some form of hosed line-ending conversion (\0x0a -> \0x0a\0x0d) happened to your binary, and that's your problem.

[Luis]

Thanks, you just saved my day

My tool to copy .bin files to .img disk image is using fscanf/fprintf and that's probably the problem. I was writing dumb code until very late that night until 7 am when writing the tool. I guess I was stupid using a char function I'll try to change it to fread/fwrite.


Cheers,

Luís

[Luis]

Solved