41
a dollar sign. Some numbers cause the printer to do other
things, too. For instance, sending a 7 sounds the printer’s bell.
Taken together, these numbers and their meanings make
up the ASCII code (pronounced ask-key), which stands for
the American Standard Code for Information Interchange.
There are ASCII codes for all the letters of the alphabet (upper
case and lower case), 0 to B,,most punctuation marks, and some
(but not all) of the functions of the printer.
There are a number of different ways to represent an ASCII
code, depending on how you are using it. For example, the
ASCII codes for the upper case letter “A” are 65 (decimal)
or &H41 (hexadecimal). Or you can just call it “A”. Appendix
B shows all of the ASCII codes.
BASIC uses the CHR$ function to represent ASCII char-
acters and many functions. To print the letter “A” we would
enter LPRINT CHR$(65). To make the printer’s bell sound,
we would enter LPRTNT CHR$(7). In general, we print a
character by entering LPRINT CHR$(ASCZZ code) to the
printer.
We can also use hex ASCII codes. Although we use only
decimal ASCII codes in this manual, in some applications it
will help if you understand what a hex code is. “Hex” is short
for hexadecimal and refers to a base-16 number (the numbers
we use in everyday life are base 10). Since the hex system needs
16 digits, it uses the numerals 0 through 9 and also the letters
A through F. In BASIC programs, you can always tell that
a number is in hexadecimal by the “&H” immediately preceding
it. The ASCII code for the letter “A” (65 in decimal) is &H41
in hex.
n Control codes
ASCII codes with values of 32 or less do not correspond to
the keys on the keyboard: These codes control many of the
printer’s functions. so we call them control codes. To enter a
control code from the keyboard, we have to press two keys
at the same time - the “control” key and one other. The other
key determines what code is sent-pressing the control (CTRL)
key and A sends ASCII code I, CTRL B sends ASCII code
2, and so on.