User-defined Characters
Run the program to see the printout below:
As you can see, both sets of characters (the original ROM
characters that the printer normally uses and the user-defined
character set) remain in the printer available for your use. The
command to switch between the two sets is used in line 90 and
110. It is:
ESC % n
If n is equal to 0, the normal ROM character set is selected (this
is the default). If n is equal to 1, the user-defined character set
is selected. If you select the user-defined character set before
you have defined any characters, the command is ignored and
the ROM characters will still be in use.
You may switch between character sets at any time - even in the
middle of a line. To try it, place semicolons at the end of lines
80 and 100 in the program above.
Copying ROM characters to RAM
After running the program above, if you select the user-defined
character set and try to print other characters, the only one that
will print is the arrow.
Since no other characters are in the
printer’s user-defined RAM area, nothing else prints. Other
characters sent to the printer do not even print as spaces; it is as
if they were not sent at all.
In many cases, you may want to redefine only a few of the
characters to suit your needs; the rest of the alphabet will work
fine as it is. As you have seen, it is possible to switch back and
forth at will between the normal character set and the
user-defined character set. It is, however, rather inconvenient.
4-28 Software and Graphics
