Software

A quick test

After you set up your application program for your printer by following the instructions in the application program manual and the instructions above, print a sample document to make sure that the program and the printer are communicating properly. If the document does not print the way you think it should, re-check the program’s printer selection and installation routine. If you are still having trouble printing, consult Chapter 6.

Computer-printer communications

Computers and printers communicate by using numerical codes to represent characters and commands. To be sure that the two devices translate the characters in the same way, a standard code has been developed-the ASCII (American Standard Code for Information Interchange). Many application programs specifically ask for ASCII codes to send printer commands.

The ASCII standard includes codes for printable characters (letters, punctuation marks, numerals, and mathematical symbols) and 33 other codes called control codes. The control codes are for such functions as sounding the beeper and performing carriage returns. Because the 33 control codes are not enough to control all possible printer functions, most printer commands are actually a sequence of two or more codes.

One of the 33 control codes, the escape code, signals the beginning of a sequence of codes. Therefore, most printer commands are sequences of codes, the first of which is the escape code. This manual uses the ASCII abbreviation ESC for this code.

When using control codes to select printer functions for an application program or programming language, check the manual for the program or language to find the appropriate method of inserting the code into the program. Further details on the methods to use are in the rest of this chapter.

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