SINGLE-DENSITY GRAPHICS
The printer fires pins 1, 3, 5, and 7 (with the respective exponential
values of 1, 4, 16, and 64) in the first column and pins 2,
4,
and 6
(exponential values
2, 8,
and
32)
in the second. And it alternates that
sequence for 50 columns-50 columns in Single-Density.
This program also mixes graphics and text on one line. It does that
by using semicolons to keep both kinds of output on the same print
line.
High-Speed Double-Density Graphics Mode
Now let’s print the same pattern in twice the normal (Single) den-
sity. Change the first
0
in line
20
to a 2 and retype the text in line
50
as
shown below:
28 A$=CHR$(27)+"*"+CHR$(2)+CHR$(50)+CHR$(0)
50
LPRINT " HIGH-SPEED DOUBLE-DENSITY GRAPHICS ";
If your computer system requires a WIDTH statement to prevent the
printer from issuing a carriage return before the graphics line is com-
plete, add it now:
7 WIDTH LPRINT 255
The format for this statement may be different for your BASIC; see
your software documentation.
HIGH-SPEED DOUBLE-DENSITY GRAPHICS
The program still prints
50
columns of dots, but now it presses them
together and prints them in half the space. They print at the same
speed as in Single-Density Graphics.
This High-Speed Double-Density Graphics Mode has one draw-
back. Because the dots are so closely packed, two dots in the same row
cannot appear in two consecutive columns. In the above program we
avoided the problem by never calling up one dot twice in succession.
If you try to print two consecutive dots, the printer simply ignores the
second one (see Figure
11-1).
146
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