Control Codes - Epson FX Series User Manual

instead of an Italic A, pay close attention to the next three paragraphs.
The original ASCII code was designed to use the decimal numbers
zero through 127. Computer systems designers soon decided to extend
this range (to 0 through
Unfortunately, some designers did not anticipate that printers would
make use of this extended range. So they designed BASIC printer
drivers that intercept any number in the upper half of the range
and automatically convert it to the lower half of the range by
255)
subtracting
128.
In these systems such a code as CHR$(193) never makes it to the
printer. The printer driver subtracts
for Italic A gets to the printer as a CHR$(65). The printer then
produces a Roman A.
For many applications, you won't need the upper half of the ASCII
codes. For others, the inability to generate codes greater than 127 will
be an obstacle. Whenever we can, we suggest ways to get around this
obstacle. In Chapter 5, for instance, we discuss Italic Mode, which is
the FX designers' method of making Italic characters easily accessible
to all users.
If you're patting yourself on the back because your printer printed
an Italic A, postpone your celebration for a bit. Nearly all computers'
BASIC programs intercept codes on their way to the printer and alter
some of them. For example, some popular systems intercept a
CHR$(10)-line feed-and send out a CHR$(13)-carriage return-
instead. Typical problem codes involve the numbers 0 and 9 to 13.
Your computer manual may alert you to these problems, Or experi-
ence may have to be your guide.
In order to help computer systems that can't send a zero in a CHR$
command, several printers' instruction sequences allow such options
as using "0" (quote-zero-quote) in place of CHR$(O). Besides mention-
ing some of these solutions within the text of this User's Manual, we
have written a troubleshooting appendix, Appendix F.

Control codes

Enough talking about problems. Here's a program line to try:
10 LPRINT CHR$(7)
Be sure to use the appropriate printer access commands for your
system.
in order to make room for more features.
255)
128,
which means that the code
(128 -
41