Apple 4400, 7300 manual Setting up a modem or other serial device

IMPORTANT Mac OS programs cannot access a port that you’ve assigned to the PC environment. If you’re trying to print, fax, or use your modem in the Mac OS environment, and you get a warning message that the port requested is busy or in use, then you need to unassign a PC COM port in the PC Setup control panel.

Setting up a modem or other serial device

From the PC environment, you can use a modem or other serial device connected to the Macintosh serial port. For best results, use the Apple DB-25 DIN-8 Mac to High-Speed Modem cable (part number M5537LL/A). If you are unable to obtain this modem cable, you can use the information in the next section to build a custom cable.

Because the Macintosh uses the RS-422 protocol, the RS-232 Ring Indicator (RI), Request to Send (RTS), and Data Set Ready (DSR) signals are not available through a Macintosh serial port. You can attempt to configure your application to use the carrier string or ignore carrier detect.

Note: The serial port on the optional PC Serial and Parallel Port card (not included) supports the RS-232 interface directly without your having to use a special cable or configure your software.

Note: For more information on setting up a modem in Windows 95 to use TCP/IP for PPP (point-to-point protocol) connections, see Appendix D, “Installing Network Client Software.”

Setting Up the PC Environment 53