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needed, so they included the escape (ESC) code to allow almost
any number of additional codes to be defined when they became
necessary.
ESC allows us to “escape” from the ordinary set of control
codes so we can specify additional functions and other infor-
mation needed for a printer function. In this manual, we’ll
write the ESC code inside broken brackets, like this - < ESC > .
< ESC > - decimal 27 - is always followed by at least one
other number; it is never used alone. The whole series of related
numbers is called an escape sequence.
R A note on command syntax
Because the readers of this manual will be running such a
wide variety of applications on so many different computers,
we can’t show the exact way of sending codes to the printer
for each one of them. Instead, as we introduce you to each
new ccmmand, we will show the commands as in this example:
<ESC> “W” 1
This command turns on expanded printing. < ESC > , as
we mentioned earlier, is the escape code (which is ASCII code
27). A letter or number in quotes (such as the “W” above)
means that the character should be sent to the printer, but
without the quotes. In our example, you should send a capital
W following the escape code. In BASIC, you could do this
in a couple of ways: by sending the character itself (e.g.
LPRINT “W”;), or by using the CHR$ function to send the
ASCII code for the character (e.g. LPRINT CHR$(87);).
Many of printer commands end with a 1 or 0. When shown
as in the above example (i.e., no quotes and no “CHRV), you
can use either ASCII code 1 (i.e., CHR$(l)) or the character
“1” (which is ASCII code 49). The same principle applies to
commands ending with 0.
So for our example above, any of these BASIC statements
will have the same result:
LPRINT CHR$(27);"W";CHR$(lJ
LPRINT CHR$(27);"W";CHR$(49)
LPRINT CHR$(27);"Wl"