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Computer and printer interaction would be terribly confusing if
different kinds of computers and printers used different numbers for
the same letter of the alphabet. Therefore, most manufacturers of
computers, printers, and software use the American Standard Code
for Information Interchange, usually referred to as ASCII (pro-
nounced ASK-Key). The ASCII standard covers the decimal num-
bers from Oto 127 and includes codes for printable characters (let-
ters, punctuation, numerals, and mathematical symbols) and a few
control codes, such as the codes for sounding the bell and perform-
ing a carriage return.
Although other codes are not standardized in the computer indus-
try, the ASCII system means that at least the alphabet is standar-
dized. A programmer or engineer knows, for example, that 72 is the
decimal code for a capital
H
and 115 is the code for a lower case s no
matter what system he or she is using.
ESCape Codes
Although the original ASCII standard was designed to use the de-
cimal numbers O through 127, computer and printer manufacturers
soon extended this range ( to O through 255) in order to make room
for more features. On the GX-80, for example, the codes from 160
through 254 are used for italic characters. Because even this ex-
tended range is not enough for all the features used on modem
printers, the range is further extended with a special code called the
Escape code. This code is often printed with the first three letters
capitalized (ESCape) or abbreviated as ESC or <ESC>.
When the <ESC> code, which has the decimal value 27, is used,
printers and computers are not restricted to only 256 instructions.
The <ESC> code is a signal that the next code will be a printer
control code instead of text to print. For example, if the printer
receives the number 69, it prints a capital E because 69 is the ASCII
code for that letter.
If,
however, the printer receives code 27 just
before the 69, it turns on emphasized mode, because <ESC> Eis
the code sequence for emphasized.
You can see how important the <ESC> code is by looking at
Appendices A, B and C. You will see that nearly every code the
GX-80 uses is an <ESC> code.
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Printer Codes
To take advantage of the many print features of the GX-80, you can
use a software program that sends the correct codes or you can use
another method to send instructions to the printer. It is not possible
to be as precise and specific as we would like in this chapter because
the GX-80 works in combination with so many different applications
programs and computer systems.
However, this chapter will lay down the general principles of how
software communicates with the printer, plus several ways in which
the codes of the GX-80 are used by word processing and business
programs. With this information and possibly some help from your
dealer or the operating manual for the applications program, full
advantage can be taken of all the features of the GX-80 that you
wish to use. Incidentally, there is no standard terminology for soft-
ware codes; thus, the terms in the software manual may differ from
the ones used here.
There are a number of ways of sending printer codes with commer-
cial software:
• Using SelecType, as described in Chapter 2.
• Instructing the program during an installation or setup procedure
enabling you to use special codes that are typed in along with
your text or data. These will be referred to as "software com-
mand" codes.
• Inserting GX-80 printer codes in the text enclosed by special
instruction characters which tell the printer that the "embedded"
codes are not text or data, but special codes for the printer.
There are three common formats for inputting printer codes either
into the program or inserting them into the text. The applications
software or its manual should tell you which one to use.
• Decimal numbers - 27, for example is the decimal number for
the <ESC> code, and 13 is the decimal number for a carriage
return.
• Hexadecimal numbers (sometimes abbreviated to hex), for ex-
ample in which the <ESC> code is lB and a carriage return is
OD. You do not have to understand hexadecimal numbers to use
them. If your software calls for hex numbers, just consult Appen-
dix C for the appropriate number.
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