Int 16 Fn FFA3  U - PC Tools V9 Dsklight - Installation Check              [-]

   AX = FFA3h
   BX = FFA3h
   CX = FFA3h

Return: BX = CX = 5555h if installed
       AX = resident code segment
Program: DSKLIGHT is a TSR included with PC Tools v9+ which displays a disk-
     access indicator on the screen; in v7 and v8, this function was
     provided by DATAMON

Note:  DSKLIGHT chains to the previous handler if BX or CX is not FFA3h