Int 16 Fn FFB8  U - PC Tools V5.1-8.0 Desktop - Get/set???                 [U]

   AX = FFB8h
   BH = subfunction
       00h get

       Return: BL = old value of ???
           CL = old value of ??? (v6.0+)
           CH = old value of ??? (v6.0+)
       nonzero set
       BL = new value for ???
       CL = new value for ??? (v6.0+)
       CH = new value for ??? (v6.0+)
       DH = ???

       Return: AL = old value replaced by CL (v6.0+)
           AH = old value replaced by CH (v6.0+)