Epson Apex-80 - Manual (Page 33)

A quick test
After setting up your application program, print a sample document
to be sure the program and the Apex80 are communicating properly. If
the document doesn’t print correctly, recheck the program’s printer
selection and installation procedure. If you’re still having trouble
printing, consult Appendix C.
Computer - Printer Communication
Computers and printers communicate by using codes to represent
characters and commands. To be sure the two devices use the same
codes, almost all manufacturers of computers, printers, and software
use the American Standard Code for Information Interchange, which
is usually referred to by its abbreviation, ASCII.
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.
Naming and using commands
The most common way of naming codes or commands is with one of
two numbering systems, decimal or hexadecimal.
The decimal system is the standard numbering system based on units
of ten, using the numerals 0-9.
2.2 Using the Apex80 with Application Programs