If your printer is not on the list or compatible with one of the printers on the list, you'll need to provide the application with some specifications about your printer (things like the baud, number of data bits, number of stop bits, type of parity, and other specifications that may be Greek to you). The reason for providing these specifications is that different printers expect to receive information from the computer at different speeds and in different forms. The specifications tell the application how to send information to the printer. You should be able to find the specifications in the manual that came with your printer. If you can't, contact your authorized Apple dealer or the printer manufacturer.
You don't need to know what specifications mean to find them in the printer manual and feed them into the application; but if you're curious, you can learn about the various specifications by reading "Changing Printer/Modem Port Settings" in Appendix A.
Some applications don't ask for the name of your printer or for specifications about your printer. They let the computer control how information is sent to the printer. If that's the case with the application you're using, and if it works, don't give it another thought. But if you're having trouble getting your document to print, you may need to change the way the computer is sending information to the printer. You can do this by changing the printer port settings in the Control Panel Program.
This section defines some terms and explains some concepts that applications may take for granted that you know. For example, you might need to know that information isn't stored inside the computer as letters and decimal numbers. It's stored as strings of 0's and 1's. Each letter, number, and punctuation mark on the Apple IIGS keyboard has its own distinct arrangement of 0's and 1's. The letter A, for example, is expressed as 1000001; B is 1000010.
Chapter 2: Once Over Lightly