This article discusses the "Port is Busy" error message with the StyleWriter II and PowerBook 500 computer.

The PowerBook 520c and 540c computers employ a single serial port which is a combination Printer/Modem port. In order to use this port for serial printing, use the following information to properly configure your PowerBook 500 series computer:

If the Express Modem is installed:

• Select Use External Modem from the Express Modem control panel.
• Select Normal from the PowerBook Setup control panel.

1. If using the PowerBook 200 series, turn OFF AppleTalk. Because the PowerBook 500 series is equipped with Ethernet, you only have to disable AppleTalk if you are using the serial port for network services. You can verify that you are using Ethernet by making sure the Network Control Panel is set for Ethernet.

2. Select the serial printer driver.

3. Select the "printer/modem" icon (or the modem icon if the printer/modem icon is not available).

A similar situation can also occur when using the Color StyleWriter 2400 or other serial printer. If you see no port selection choices, make sure the PowerBook Setup control panel is set for Normal. Future Apple serial printer drivers will provide only one port selection (called the "Printer/Modem") in the Chooser.

This issue can also occur when printing to any serial printer with other PowerBook computers that have a single serial port including the PowerBook 150 and the PowerBook 200 series.