INT 21 - DOS 3.2+ - IOCTL - GENERIC BLOCK DEVICE REQUEST
        AX = 440Dh
        BL = drive number (00h=default,01h=A:,etc)
        CH = category code
            08h disk drive
            00h-7Fh reserved for Microsoft
            80h-FFh reserved for OEM/user-defined
        CL = minor code (function) (see below)
        DS:DX -> (DOS) parameter block (see below)
        SI:DI -> (OS/2 comp box) parameter block (see below)
Return: CF set on error
            AX = error code (01h,02h) (see AH=59h)
        CF clear if successful
            DS:DX -> data block if CL=60h or CL=61h
Notes:  DOS 4.01 seems to ignore the high byte of the number of directory
          entries in the BPB for diskettes.
        functions 46h and 66h undocumented in DOS 4.x, documented for DOS 5+
        the DUBLDISK.SYS v2.6 driver only supports minor codes 60h and 67h
        DR-DOS 3.41-6.0 only support minor codes 40h-42h and 60h-62h; all
          other minor codes return error code 16h
SeeAlso: AX=440Ch,AH=69h,INT 2F/AX=0802h,INT 2F/AX=122Bh

Values for minor code:
 00h    (OS/2)  \ used to lock/unlock a drive
 01h    (OS/2)  /
 40h    set device parameters
 41h    write logical device track
 42h    format and verify logical device track
 46h    (DOS 4+) set volume serial number (see also AH=69h)
 47h    (DOS 4+) set access flag
 50h    (PCMCIA) attribute memory write
 51h    (PCMCIA) common memory write
 52h    (PCMCIA) force media change
 53h    (PCMCIA) erase drive
 54h    (PCMCIA) erase media
 56h    (PCMCIA) set erase status callback
 57h    (PCMCIA) append Card Information Structure (CIS) tuple
 58h    (PCMCIA) erase CIS tuples
 60h    get device parameters
 61h    read logical device track
 62h    verify logical device track
 66h    (DOS 4+) get volume serial number (see also AH=69h)
 67h    (DOS 4+) get access flag
 68h    (DOS 5+) sense media type
 70h    (PCMCIA) attribute memory read
 73h    (PCMCIA) get memory media information
 76h    (PCMCIA) get erase status callback
 77h    (PCMCIA) get first Card Information Structure (CIS) tuple
 78h    (PCMCIA) get next CIS tuple

Format of parameter block for functions 40h, 60h:
Offset  Size    Description
 00h    BYTE    special functions
                bit 0 set if function to use current BPB, clear if Device
                        BIOS Parameter Block field contains new default BPB
                bit 1 set if function to use track layout fields only
                        must be clear if CL=60h
                bit 2 set if all sectors in track same size (should be set)
                bits 3-7 reserved
 01h    BYTE    device type (see below)
 02h    WORD    device attributes
                bit 0 set if nonremovable medium
                bit 1 set if door lock ("changeline") supported
                bits 2-15 reserved
 04h    WORD    number of cylinders
 06h    BYTE    media type
                for 1.2M drive
                    00h 1.2M disk (default)
                    01h 320K/360K disk
                F8h for DUBLDISK.SYS v2.6 expanded drives
                always 00h for other drive types
 07h 31 BYTEs   device BPB (see AH=53h), bytes after BPB offset 1Eh omitted
---function 40h only---
 26h    WORD    number of sectors per track (start of track layout field)
                max 63
 28h  N word pairs: number,size of each sector in track

Values for device type:
 00h    320K/360K disk
 01h    1.2M disk
 02h    720K disk
 03h    single-density 8-inch disk
 04h    double-density 8-inch disk
 05h    fixed disk
 06h    tape drive
 07h    (DOS 3.3+) other type of block device, normally 1.44M floppy
 08h    read/write optical disk
 09h    (DOS 5+) 2.88M floppy

Format of parameter block for functions 41h, 61h:
Offset  Size    Description
 00h    BYTE    special functions (reserved, must be zero)
 01h    WORD    number of disk head
 03h    WORD    number of disk cylinder
 05h    WORD    number of first sector to read/write
 07h    WORD    number of sectors
 09h    DWORD   transfer address

Format of parameter block for function 42h:
Offset  Size    Description
 00h    BYTE    reserved, must be zero (DOS <3.2)
                  bit 0=0: format/verify track
                        1: format status call (DOS 3.2+), don't actually format
                  bits 1-7 reserved, must be zero
                value on return (DOS 3.3+):
                  00h   specified tracks, sectors/track supported by BIOS
                  01h   function not supported by BIOS
                  02h   specified tracks, sectors/track not allowed for drive
                  03h   no disk in drive
 01h    WORD    number of disk head
 03h    WORD    number of disk cylinder

Format of parameter block for function 62h:
Offset  Size    Description
 00h    BYTE    reserved, must be zero (DOS <3.2)
                  bit 0=0: verify single track
                        1: verify multiple tracks
                  bits 1-7 reserved, must be zero
                value on return (DOS 3.3+):
                  00h   specified tracks, sectors/track supported by BIOS
                  01h   function not supported by BIOS
                  02h   specified tracks, sectors/track not allowed for drive
                  03h   no disk in drive
 01h    WORD    number of disk head
 03h    WORD    number of disk cylinder
 05h    WORD    number of tracks to verify (equivalent to 255 or fewer sectors)

Format of parameter block for functions 46h, 66h:
Offset  Size    Description
 00h    WORD    (call) info level (should be 0000h)
 02h    DWORD   disk serial number (binary)
 06h 11 BYTEs   volume label or "NO NAME    "
 11h  8 BYTEs   filesystem type "FAT12   " or "FAT16   " (CL=66h only)

Format of parameter block for functions 47h, 67h:
Offset  Size    Description
 00h    BYTE    special-function field (must be zero)
 01h    BYTE    disk-access flag, nonzero if access allowed by driver

Format of parameter block for function 68h:
Offset  Size    Description
 00h    BYTE    01h for default media type, 00h for any other media type
                (see also INT 13/AH=20h)
 01h    BYTE    02h for 720K, 07h for 1.44M, 09h for 2.88M

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