INT 15h, C1h (193)         Extended BIOS Data Area                PS/2

     Returns the address of the Extended BIOS Area.

             On entry:          AH    C1h

             Returns:           For PCjr and PC:
                                    AH = 80h, CF = 1
                                For PC XT, AT, XT 286, Convertible
                                    AH = 86h, CF = 1
                                For All Others:
                                    IF CF is not 1, then ES = Extended BIOS
                                    data area segment address.

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     This service gives you quick access to the extended BIOS data area used
     in the PS/2. If the carry flag is set on return, the extended BIOS data
     area is not being used. If the carry flag is not set, the segment address
     of the extended data area is in ES.

             Notes:      The ROM BIOS uses the extended data area as a
                         storage area for transient data. For example, the
                         addresses of device drivers are stored here.