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4fi
- the "control" key and one other. The other key determines
what code is sent - pressing
the control (CTRL) key and A
sends ASCII code 1, CTRL B sends ASCII code 2, and so on.
Your printer has a lot of control codes to let you do some
useful things. Let's try one that we've mentioned
several times
already:
10 ' Demo of ASCII
code
20 LPRINT CHR$(7)
30 END
RUN
That's the printer's bell (we call it that even though it sounds
like a buzzer). We'll learn more about it in later -
we just
wanted to show you a control code that would get your attention
right away!
There are four common ways of referring
to a control code:
the name of the code or its abbreviation,
the decimal ASCII
value, the hexadecimal
ASCII value, and the "CTRL-" value.
For example, the ASCII code that causes the printer to advance
the paper one line is decimal 10. This code may be referred to
by any of the following:
-
line feed
- the name of the code
(LF)
- its abbreviation
ASCII 10
- its decimal value
ASCII &HOA
- its hexadecimal
value (the &H signifies
hex)
-
CHR$(lO)
- the way it's used in BASIC
CTRL- J
- the way you send it from a keyboard
Of course, most of the time we don't need to bother with
these. The computer
is smart enough to know that when we
press the "A" key we want to print the letter "A" - it takes
care of all the intermediate
steps.
Appendix C is a table that shows the various names for each
code so you can convert back and forth. The microcomputer
world is not very consistent
in describing
ASCII codes, so it's
important
that you have a basic knowledge
of them.
-
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