Bug in function INT13h/AH=41h ?

[Laaca]

I have a suspection about bug in attached USB drives.
If I call function INT13h/AH=41h the returned value in AH is always 0.
I think it is a bug.
And in CL is 1. Is it supposed to be so? Maybe should be 3 or 7 ?

[Bret]

If AH is 0 on return, that is indeed a bug. It should be 1. I will look into that and fix it in the next version.

CL = 1 is correct. The driver only provides a very basic set of extended INT 13h functions. It does not support removable disk functions (bit 1 of CL), since USB disks almost never correctly support removable media functions, even when they have removable media. The driver also does not support EDD functions (bit 2 of CL), since the main purpose of EDD is to provide the real physical parameters of the disk ("real" CHS values, DMA info, etc.) that don't apply to USB disks.