Int 2F Fn 4A11  - Dblspace.bin - "activatedrive" - Mount Compressed Drive  [d]

   AX = 4A11h
   BX = 0005h
   DL = drive number (0=A:) to assign to new drive
   ES:SI -> activation record (see below)

Return: status returned in activation record (see below)

See Also: AX=4A11h/BX=0000h,AX=4A11h/BX=0006h

Format of activation record:
Offset Size    Description
 00h  2 BYTEs  signature "MD" (4Dh 44h)
 02h   BYTE    4Dh ('M') mount command
 03h   BYTE    error code (set to FFh before calling)
       00h successful
       01h drive letter not available for DoubleSpace
       02h drive letter already in use
       03h no more disk units (increase MaxRemovableDrives in .INI)
       09h CVF too fragmented
 04h   BYTE    host drive number (0=A:)
 05h   ??? DISK_UNIT structure (not documented)