104
nation of dots. For example, if the data representing “1” was
sent to the print head, only the bottom pin would fire; if “2”
was sent, only the second pin from the bottom would fire, and
if “3” was sent, the two bottom pins would fire, and so on.
Columns of these dots side by side make all the characters.
0
0
I 0.0.
g-g a
0 :- 0.0.
g : 0 : .
00 0 0.0. 0
g 0.0.
0- l 000 :-
0
Figure 7-1. As the printhead moves across the page, each sf the pins
prints a row of dots.
DESIGNING YOUR OWN CHARACTERS
Standard characters are permanently stored in the printer’s
ROM (Read Only Memory), but characters you design are
downloaded and stored in RAM (Random Access Memory)
for use.
Designing and printing your own characters has two re-
quirements: firstly, designing the shape of the character, cal-
culating the data necessary to make the shape, and sending
that data to the printer, and secondly, sending the command
to print the do&loaded characters instead of the standard
characters. There are a number of design constraints for
download draft quality characters:
l The matrix or grid on which you design the characters
is six boxes wide by nine boxes high.
l Horizontally, dots may be centered in a box, or may
straddle a line, making the actual character grid 11