Int 25 Fn CDCD  - Stacker - Get Device Driver Address                      [d]

   AX = CDCDh
   DS:BX -> buffer for address (see below)
   CX = 0001h
   DX = 0000h

Return: AX = CDCDh if Stacker installed
       DS:BX buffer filled

Format of driver address buffer:
Offset Size    Description
 00h   WORD    signature CDCDh
 02h   WORD    ??? 0001h
 04h   DWORD   pointer to start of Stacker device driver

Format of device driver:
Offset Size    Description
 00h   WORD    signature A55Ah
 02h   WORD    Stacker version * 64h
 04h   WORD    offset of volume-specific information offset table
       (list of WORDs, one per drive, containing offsets to various
       information)
 06h 56 BYTEs  n/a
 3Eh   BYTE    volume number, set after INT 21/AX=4404h
       (use to index into volume-specific info offset table)
 3Fh 19 BYTEs  n/a
 52h  4 BYTEs  ASCII string "SWAP"
 56h 26 BYTEs  drive mapping table (one byte for each drive A: through Z:)

Format of Stacker boot record:
Offset Size    Description
1F0h  8 BYTEs  Stacker signature (first byte is CDh)
1F8h   DWORD   pointer to start of Stacker device driver
1FCh   WORD    Stacker volume number
1FEh   WORD    ???