Mac OS: Chooser Defaults to Modem Port

This article describes why a serial printer driver may default to the modem port within the Classic Networking architecture.

AppleTalk tends to take over the printer port when active, preventing a serial printer from using it. This causes the serial printer's driver to choose the modem port. To resolve this issue, turn off AppleTalk.

Making AppleTalk inactive (either in the Chooser or the AppleTalk control panel) is not sufficient, since the resources are loaded at startup.

Follow these steps to make AppleTalk inactive under Classic Networking:


To verify that AppleTalk is inactive, open the Chooser; the AppleTalk Inactive button should be set. Note that using file sharing or Apple Remote Access makes AppleTalk active again.

For additional information on how to turn off AppleTalk under Open Transport, please see article 24346: "Mac OS: AppleTalk "Port in Use" Error"

Additional Workaround

Install Apple Remote Access Client, which adds the option "Remote Only" to the AppleTalk Control panel. Choosing "Remote Only" routes AppleTalk to "Remote Only", freeing up your printer port for use by your serial printer.

Published Date: Feb 18, 2012