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INT 15h, C3h (196)         Programmable Option Select (POS)       PS/2

     Interface to the Programmable Option Select (POS) of the Micro Channel.

   AL = 0 Get Base POS Address

                 On entry:          AH    C4h
                                    AL    00 . Get POS base address

                 Returns:       For PCjr and PC:
                                    AH = 80h, CF = 1
                                For PC XT, AT, XT 286, Convertible, PS/2 30:
                                    AH = 86h, CF = 1
                                For All Others:
                                    CF = 0 . Operation successful
                                                AL = 0
                                                DX = Base POS register address
                                       = 1 . Operation unsuccessful

  ---------------------------------------------------------------------------
   AL = 1 Enable Slot for Setup

                 On entry:          AH    C4h
                                    AL    01 . Enable slot for setup

                 Returns:       For PCjr and PC:
                                    AH = 80h, CF = 1
                                For PC XT, AT, XT 286, Convertible, PS/2 30:
                                    AH = 86h, CF = 1
                                For All Others:
                                    CF = 0 . Operation successful
                                                AL = 1
                                                DX = Slot number
                                       = 1 . Operation unsuccessful

  ---------------------------------------------------------------------------
   AL = 2 Adapter Enable

                 On entry:          AH    C4h
                                    AL    02 . Adapter enable

                 Returns:       For PCjr and PC:
                                    AH = 80h, CF = 1
                                For PC XT, AT, XT 286, Convertible, PS/2 30:
                                    AH = 86h, CF = 1
                                For All Others:
                                    CF = 0 . Operation successful
                                                AL = 2
                                       = 1 . Operation unsuccessful

  ---------------------------------------------------------------------------

     This service provides a consistent interface to the Programmable Option
     Select of the Micro Channel (MCA) in PS/2 models 50, 60, 70, and 80.

     It is a special feature of the Micro Channel that you can now set in
     software information that required dip switches before. For example, you
     can enable or disable options in MCA slots. This service allows you to
     take advantage of this new capability.