Int 21 Fn 4404  - Dubldisk.sys V2.6 - Get Info                             [k]

   AX = 4404h
   BL = drive number of DoubleDisk drive (00h = default, 01h = A:, etc.)
   CX = number of bytes (000Ah-0014h, call ignored otherwise)
   DS:DX -> data record (see #1217)

Return: CF clear if successful
       AX = number of bytes read
   CF set on error
       AX = error code (01h,05h,06h,0Dh) (see #1366 at AH=59h/BX=0000h)
Program: DUBLDISK.SYS is the device driver portion of DoubleDisk, a disk
     expander by Vertisoft Systems, Inc.

Note:  the installation check for v2.6 consists of scanning memory for the
     signature "FAT 2.6  byte:", which is immediately followed by a data
     table (see #1218)
BUG:   VOPT (a disk optimizer by Golden Bow Software) assumes that any driver
     which returns the "correct" number of bytes when the first word of
     the buffer for the data record contains the signature value 4444h is
     DoubleDisk; a workaround is for the non-DoubleDisk driver to return
     no data if the signature is present

See Also: AX=440Dh"DOS 3.2+"
Index: installation check;DUBLDISK.SYS

Format of DUBLDISK data record:
Offset Size    Description (Table 1217)
 00h   WORD    (call) signature 4444h
 02h   BYTE    (call) function
           00h ???
           01h ???
---function 00h---
 02h   BYTE    (ret) ???
 03h   BYTE    (ret) ???
---function 01h---
 02h   WORD    (ret) 4444h
 04h   WORD    allocation unit size???
 06h   WORD    ???
 08h   WORD    ???
 0Ah   BYTE    ???

Format of DUBLDISK signature data table:
Offset Size    Description (Table 1218)
 00h  5 BYTEs  ???
 05h   BYTE    first drive number
 06h   BYTE    number of drives
 07h   ???