Function 24h (36)        Set Random-Record Field, Using FCBs

    Sets the random-record field in the FCB.

       On entry:      AH         24h
                      DS:DX      Pointer to an opened FCB

       Returns:       Nothing

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    This function sets the random-record field to correspond to the
    current block and record fields in the FCB.

       Notes:         This function facilitates switching from sequential
                      to random I/O.