INT 15h,  84h (132)      Joystick Support                                many

    Reads the current joystick switch settings or reports the current
    joystick resistive inputs.

       On entry:      AH         84h
                      DX         Subservice
                                 00h - Read current switch settings
                                 01h - Read resistive inputs

       Returns:       Carry      Set if error, else cleared
                      If DX = 00h (Read current switch settings):
                                 AL     Bits 7 to 4 contain switch settings
                      If DX = 01h (Read resistive inputs):
                                 AX     A(x) value
                                 BX     A(y) value
                                 CX     B(x) value
                                 DX     B(y) value

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       Notes:         This service is available only for the AT, XT dated
                      after 11/08/82, and XT-286.