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boeckmann

Aachen, Germany,
09.02.2023, 17:19
 

INT21 function 7304h (Developers)

Hi,

has anyone knowledge of the DOS 7 API function 7304h? Documentation I found on the net is sparse and even RBIL is a little short of information.

The reason I am asking:

I noticed that ranish, when running under Win9x, correctly formats existing FAT-32 partitions which eventually get corrupted by Win9x because it writes back old fsinfo (free cluster count etc.). The above functions seem to exist to correctly notify Win9x about the format process.

In the recent days I have implemented a routine utilizing this function (sub functions 0 and 1) to inform Win9x about the new free cluster count, and that seems to fix the problem.

But I am not sure if it is a) the right way to do it and b) if the order in which I call the functions and doing the file system locking via INT 21h function 440Dh,484Bh are correct.

What I found out until now is that Microsoft format.com in its Win95 version seems to utilize sub functions 0 and 1. But I am not yet sure in which order the functions are called. Interestingly the FreeDOS format routine instead seems to use sub function 2.

The question is also if these functions should be called when the lock (via 440Dh) is in effect or after I released the lock. Also I am wondering why there are two versions of the locking functions. One for FAT-16 (sub function 084bh and one for FAT-32 484bh). I did not notice any effect when changing the locking function. At least when running under Win95. Haven't tested Win98 though.

Perhaps someone can give me a hint.

Greetings, Bernd

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