Int 33 Fn Sect  - Ms Mouse - Reset Driver And Read Status                  [!]

   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.
   Logitech MouseWare v6.30 reportedly does not support CGA video modes
     if no CGA is present when it is started and the video board is
     later switched into CGA emulation

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