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Chapter 4
Control Codes
This chapter introduces you to the control codes you can use to
send instructions from your computer to your printer. If you already
know how to program your printer, you’ll want to know how control
codes work with the
LQ-1500.
You’ll also be interested in Appendixes
A and E which provide the control codes.
Please note that this chapter contains technical information and
you don’t have to read it in order to operate your printer or to perform
ordinary word processing operations. If you don’t know how to pro-
gram a printer, you can use your applications software to find out
how to control the LQ-1500.
Computer-to-Printer-Communications
Alphabetical characters (letters) are foreign to computers; comput-
ers only know numbers. However, computers still manage to do a
good job of manipulating the letters that we use for word processing.
The secret lies in the fact that a computer doesn’t manipulate letters at
all-it just manipulates numbers that represent letters and turns these
numbers into the letters that we see on the screen and the printout.
The computer communicates with the printer by means of numeri-
cal codes. There are 256 different codes that the computer can send to
the printer, represented by the numbers from 0 to 255. Since there are
many different kinds of computers and many different kinds of print-
ers, a standard set of codes was developed that almost all computers
use to comunicate with printers. This set of codes is called the Ameri-
can Standard Code For Information Interchange, or ASCII for short.
There are ASCII codes for all the letters in the alphabet (both upper-
and lowercase), the numbers from 0 to 9, most punctuation marks,
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