0:418h                   Extended Shift Status

 Length: 1 byte

                        Extended Shift Status

               7 6 5 4 3 2 1 0
               x . . . . . . .      Ins key is pressed
               . x . . . . . .      Caps Lock key is pressed
               . . x . . . . .      Num Lock key is pressed
               . . . x . . . .      Scroll Lock key is pressed
               . . . . x . . .      Pause key locked
               . . . . . x . .      SysReq key is pressed
               . . . . . . x .      Left Alt key is pressed
               . . . . . . . x      Right Ctrl key is pressed

    Bits 2 through 0 are valid only for the 101/102-key keyboard.

    On the PCjr, bit 2 is used to indicate if Key Click is active.