To transfer information between an Apple III and a Macintosh, use Access III on the Apple III and MacTerminal on the Macintosh. To connect an Apple III to Macintosh Plus, use the peripheral adapter cable and the Macintosh 512K to ImageWriter I cable (590-0169). If using the Apple III serial card, have the card set to no - modem eliminator. If using the built-in port C, make sure you're using the .RS-232 driver rather than the .PRINTER driver. You can find the .RS-232 driver for the built-in port C on the System Utilities Data diskette. Make sure both systems are set for the same baud rate, data bits, and so forth, and then simply set one system up to send a file and the other one to receive a file.