NAME
        ReadExpansionRom - read a boards configuration ROM space

   SYNOPSIS
        error = ReadExpansionRom( board, configDev )
        D0                        A0     A1

   FUNCTION
        (Not typically called by user code)

        ReadExpansionRom reads a the ROM portion of an expansion
        device in to cd_Rom portion of a configdev structure.
        This routine knows how to detect whether or not there is
        actually a board there,

        In addition, the ROM portion of a new style expansion board
        is encoded in ones-complement format (except for the first
        two nybbles -- the er_Type field).  ReadExpansionRom knows
        about this and un-complements the appropriate fields.

   INPUTS
        board - a pointer to the base of a new style expansion board.
        configDev - the configdev structure that will be read in.
        offset - a logical offset from the configdev base

   RESULTS
        error - If the board address does not contain a valid new style
                expansion board, then error will be non-zero.

   EXAMPLES

        configDev = AllocConfigDev();
        if( ! configDev ) panic();

        error = ReadExpansionBoard( board, configDev );
        if( ! error ) {
                configDev->cd_BoardAddr = board;
                ConfigBoard( configDev );
        }

   SEE ALSO
        readexpansionbyte(), writeexpansionbyte()