Format of request block:
Offset Size Description )
00h WORD 001Bh
02h BYTE drive number (0=default, 1=A:, ...)
03h BYTE ???
04h WORD ???
06h DWORD far pointer to data area
0Ah WORD ???
0Ch DWORD far pointer to data area
10h WORD buffer for result
SeeAlso: #03424,#03426