"NiTiN" asked:
> I've got some really simple code that boots the system and displays a
> string. I've looked at a couple of examples and I'm aware of the load
> to 0x7c00. My jump references are fine but when I try to access
> variables, I get nulls instead of the actual data.
I'd try a colon
helloMsg: db 'A'
__
wolfgang
_________________________
> Here's the source code:
> bits 16
> org 0x7c00
>
> jmp start
>
> helloMsg db 'A'
>
> start:
> mov al, [helloMsg] ;copy the A
> cmp al, 65
> jne wrongChar
>
> call printChar ;print the A
> jmp end
>
> wrongChar:
> mov al, 66 ;print B if wrong character
> call printChar
>
> end:
> jmp $
>
> printChar:
> mov ah, 0eh
> ;mov al, 65
> mov bh, 0h
> mov bl, 7h
> int 10h
> ret
>
> ;510 bytes plus the 2 byte signature
> zero_padding: times 510 - ($ - $$) db 0
>
> ;boot signature
> boot_sig: dw 0xaa55
>
>
> The output I get on running this code is 'B' when it should be 'A'. I
> must be missing something.
>
> My setup is VMWare running on Windows, and an NASM compiler.
>
> Any help is appreciated.
>
> Regards,
> Nitin
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