0040h:0018h           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      Left 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.