Int 33 Fn 0000  - MS Mouse - Reset Driver And Read Status                  [M]

   AX = 0000h

Return: AX = status
       0000h hardware/driver not installed
       FFFFh hardware/driver installed
   BX = number of buttons
       0000h other than two
       0002h two buttons (many drivers)
       0003h Mouse Systems/Logitech three-button mouse
       FFFFh two buttons

Notes: to use mouse on a Hercules-compatible monographics card in graphics
     mode, you must first set 0040h:0049h to 6 for page 0 or 5 for page 1,
     and then call this function.  Logitech drivers v5.01 and v6.00
     reportedly do not correctly use Hercules graphics in dual-monitor
     systems, while version 4.10 does.
   the Logitech mouse driver contains the signature string "LOGITECH"
     three bytes past the interrupt handler; many of the Logitech mouse
     utilities check for this signature.

See Also: AX=0011h,AX=0021h,AX=002Fh,INT 62/AX=007Ah,INT 74