Commodore CBM - The CHR$ Function

THE CHR$ FUNCTION: PROGRAMMING CHARACTERS IN ASCII
Certain PET characters cannot be programmed by enclosure within
quotation marks.
It is possible to program these select characters using their
ASCII values.
ASCII is the code name for "American Standard Code for Informa-
tion Interchange."
ASCII assigns a unique number in the range of 0 ta 255 ta each
alphabetic and numeric character. and ta various symbolic characters. Table
6-4
in Chapter 6 lists the standard ASCII codes. Appendix A shows the PET ASCII
codes. Notice that the
PET ASCII chart assigns numbers ta cursor contrais and
graphie characters peculiar ta the
PET.
The CHR$ function translates an ASCII code number into its equivalent
character.
The format of the CHR$ function is:
CHR$( )
L ASCII number from 0 to 255 of
desired character or control
Ta obtain the correct ASCII code for the desired character. refer ta Appendix
A. Scan the columns until vou find the needed character or cursor control. then
note the corresponding ASCII code number. Insert its
ASCII code between the
two parentheses of the function. For example. ta create the symbol "$" from its
ASCII code number. first scan the PET ASCII chart for "$". "$" has two ASCII
values:
36 and 100. Which value should vou use? Actually either number works
just
as weil. But for good programming technique. once vou select one number
over the other.
use that number consistently throughout the program. We will use
number
36 and insert it into the function as follows:
CHR$(36)
Try printing this character in calculator mode on your PET.
?CHR$(36)
$
Now. try printing ASCII code 100:
?CHR:$ 0:: 10(1)
:$
The result is the sa me. Experiment in calculator mode using any ASCII code from
Ota 255.
Vou can use the CHR$ function in a programmed PRINT statement as
follows:
F.~EFŒI'''' •
10 PRINT CHR$(36);CHR$(42);CHR$(166)
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