Receive Broadcast Datagram Command (Net Bios, 23h)

        This command waits for a SEND BROADCAST message. The NUM field
        must contain a valid name number. The BUFADR and BUFLEN fields
        are set to the size and maximum length of the receive data
        buffer. There is no time-out on this command. The name of the
        sender is returned in CALLNAME.

        Each SEND BROADCAST satisfies all outstanding RECEIVE BROADCAST
        commands on the network.

        The actual size of the received data is returned in BUFLEN. If
        the maximum buffer length was smaller than the length of the
        data, then the buffer is filled to the maximum and RETCODE = 06h
        is returned. The remaining data is lost.