see, the capital letters use the top seven wires of the printhead,
and the descenders (such as the lower case “p” shown) use the
bottom seven pins. As the printhead moves across the page (in
either direction - that’s what is meant by bi-directional print-
ing) it prints one column of dots at a time. Each time a dot is sup-
posed to print an electromagnet inside the printhead causes the
appropriate wire to strike the ribbon (making this printer an im-
pact printer).
1
I
Figure 6- 1. The letter “C” is created by printing 15 dots.
5gure 6-2. As the printhead moves across the page, each of the
wires prints one row of dots.
THE PRINT MATRIX
All of the standard characters that this printer prints are form-
ed from patterns of dots that are permanently stored in the
printer’s ROM (read-only memory). This includes all of the stan-
dard ASCII characters, and special characters, the international