INT 16h,  02h (2)        Get Shift Status                                 all

    Returns the current keyboard shift status.

       On entry:      AH         02h

       Returns:       AL         Shift status

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               Shift Status (AL)
               7 6 5 4 3 2 1 0
               1 . . . . . . .      Insert locked
               . 1 . . . . . .      Caps Lock locked
               . . 1 . . . . .      Num Lock locked
               . . . 1 . . . .      Scroll Lock locked
               . . . . 1 . . .      Alt key is pressed
               . . . . . 1 . .      Ctrl key is pressed
               . . . . . . 1 .      Left Shift key is pressed
               . . . . . . . 1      Right Shift key is pressed

       Notes:         This shift status byte is obtained from the byte at
                      memory location 0:0417h.

                      See Service 12h to obtain the shift status for the
                      enhanced (101/102-key) keyboard.