Int 21 Fn 4405  - Dos 2+ - Ioctl - Write To Block Device Control Channel   [D]

   AX = 4405h
   BL = drive number (00h = default, 01h = A:, etc)
   CX = number of bytes to write
   DS:DX -> data to write

Return: CF clear if successful
       AX = number of bytes actually written
   CF set on error
       AX = error code (01h,05h,06h,0Dh) (see #1366 at AH=59h/BX=0000h)

Notes: format of data is driver-specific
   this function was not supported by Digital Research's DOS-Plus

See Also: AX=4403h"DOS",AX=4404h"DOS",INT 2F/AX=122Bh