when we press the “A” key on our keyboard we want to print
the letter “A”. The computer takes care of all the rest.
But there are a number of ASCII codes that don’t have keys
on the keyboard. The most important of these codes are the codes
that have ASCII values below 32. These codes control many of
SR- 10/l 5’s functions. Even though there aren’t keys for these
codes, most keyboards can send these codes. It’s done by holding
down the “control” key (many times marked CTRL) and si-
multaneously pressing a letter key. The particular letter key that
is pressed determines what code is sent. Control and A sends
ASCII code 1, control and B sends ASCII code 2, and so on.
Because of the way they are created, these codes are often referred
to as “control-A” etc.
So there are four common ways of referring to the same set
of codes: the character or name of the code, the decimal ASCII
value, the hexadecimal ASCII value, and the “control-” value.
For example, the code that causes SR-lo/15 to advance the
paper one line is ASCII 10 (decimal). This code is commonly
referred to by all the following names:
line feed - its name
<LF> - the abbreviation of its name
ASCII 10 - its decimal value
ASCII OAH - its hexadecimal value (the H signifies hex)
CHR$( 10)
- the way it’s used in BASIC
control-J -
the way you send it from a keyboard.
There’s a chart in Appendix F that shows these side-by-side so
that you can convert back and forth.
The reason that we are telling you all this about ASCII codes
is that people are not very consistent about how they describe
ASCII codes. We are going to help you use SR- 10/l 5 with
commercial software, but we don’t know what its documentation
is going to call the various codes. So if you know all the different
things that the codes might be called, it will be easier to figure
out what it is trying to tell you.
Now, armed with the knowledge of what to look for, you can
delve into the manuals of your commercial software and dig out
the secrets of how to send “control codes” to your printer. When
you find the method that your program uses, then you can shop
through this manual to find the function that you want to use.
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