Table 1
                Interface Module Identifiers Accessible to
                                a Task Module

                Identifier              Function
                void setcom(void)       Initializes the serial interface
                                        for baud rate, etc.
                int rxready(void)       Returns nonzero if serial input
                                        byte is available; 0 if not.
                int rxbyte(void)        Returns serial input byte.
                int txready(void)       Returns nonzero if serial output
                                        byte can be accepted; 0 if not.
                void txbyte(int)        Sends a serial output byte.
                int kbhit(void)         Returns 1 if keyboard byte is
                                        available; 0 if not.
                int getch(void)         Reads a keyboard byte.
                void putch(int)         Writes a byte to console screen.
                void cleanup(void)      Restores standard bootup
                                        interrupt configuration.
                int comerror            Indicates receiver overrun error
                                        (bit 0), parity error (bit 1),
                                        framing error (bit 2), and
                                        ring-buffer overflow (bit 3).

                Note: All these identifiers should be declared as extern
                in a task module if modules are to be combined by
                linking.