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Putting Gemini to Work
Transmitting the Codes
The easiest way to transmit functional control codes is to build
them into the software program that sends the regular codes for
letters and numerals. Sending the control codes to the printer by
building them into the program allows you to change the printing
instructions during the program. This gives you total control to
print what you want, the way you want to print it.
You can also send control codes to the printer using the
computer system’s “command level” functions before running a
program.
All of this discussion about sending codes for special printing
effects should not be confused with the “printing codes and
commands” that are a part of commercially available word
processing software programs. Word processing programs have
built-in codes for some (but not all) special effects, such as bold
type or underscoring. But Gemini can do more “tricks” than the
word processing programs know to request. “Recycling” (that is,
fixing) word processing programs so they are fully compatible with
Gemini’s capabilities requires “Patching”the programs. All this
is discussed in the section entitled “Word Processing Software:’
toward the end of this chapter.
Because of its simplicity, availability, and popularity, we will
use BASlC(a computer language) to demonstrate and learn about
the Gemini printer. Other languages, such as PASCAL, COBOL,
FORTRAN, etc., could also be used, but to keep this training
exercise short and simple, we’ll stick to “BASICS?
If you are unfamiliar with BASIC, you might start by turning
to the user’s manual that came with your computer. There’s almost
certainly a chapter or two about BASIC. You might turn your
attention for a few minutes to reading in your computer’s manual
about how to set your computer up for running a program in
BASIC.
Internally, your computer uses a binary code (sometimes
expressed as “zeros” and “ones”) to convey information. The
ASCII codes in Appendix H are decimal(in that they are based on
ten numbers - 0 through 9), and hexadecimal (based on
16number mathematical system). In our sample programs, we’ll
use the ASCII decimal equivalents.
In BASIC, the CH/?$function is used to convert the decimal
ASCII code into your computer’s binary code. Thus,
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