VOGONS


First post, by tigrou

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I am debugging a game under DOSBox and would like to see code where it output MIDI notes (for music). I suspect this is either done in the main loop or in the timer interrupt handler.

Ideally, I would create a breakpoint that activates when anything is written to 0x330 port (using OUT dx, al). Am I right ?
Is this something possible in DOSBox ?

I already read the guide : Guide to the DOSBox debugger
but it does not help.

Reply 1 of 1, by junglemontana

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I think this is not possible... Only basic breakpoints (break at address xxx), interrupt breakpoints (break when interrupt xxx is about to be executed [with al=yyy and ah=zzz]) and memory change breakpoints (break when memory at address xxx is changed) can be set. Just my 2cents.

Have you tried to find the interesting code using a disassembler? Search for "mov dx, 0x330" for example. Or "mov dx, 0x330; out dx, ax".

Searching for symbolic assembly may be annoying or not possible, but searching for raw bytes is easier...