Different printers and different remote computers expect to receive information at different speeds and in different configurations. That's why it's important that you be able to change the way information is sent.
The printer port is configured to work automatically with the ImageWriter series of printers and with many other popular serial printers. The modem port is configured to work automatically with most commercial information services you'll be accessing with your modem. However, if your device requires a different configuration or if you want to use a modem in the printer port and a printer in the modem port, you'll need to change the data configuration. There are two ways to do this: from within an application or by using the Control Panel Program. The configuration you specify in an application overrides the Control Panel setting for a port.
How do you know whether your application is overriding the Control Panel settings for the port? If the application gives you a list of printers and asks you to choose yours from the list, it's going to send the document in the correct configuration for the printer you choose and will ignore the Control Panel settings for the port.
A tip: Even if your printer is not on the list, try selecting each of the printers on the list. If your printer happens to have the same configuration as one of those on the list, you'll save yourself the bother of supplying specifications about your printer.
If the application asks you to supply a list of specifications about how your printer or the remote computer wants to receive data (baud, number of data bits, stop bits, and the like), ifs going to send the document according to those specifications and will ignore the
Control Panel settings for the port. You should be able to find the specifications for your printer in the manual that came with it or, for an information service, in the brochure you got when you subscribed to the service.
By the way: The specifications you'll be asked for in an application are the same specifications you'll set by using the Control Panel Program, so if you aren't sure what the application means by data bits, stops bits, and parity, read the explanations in the following sections.
Changing printer/modem port settings