Each time the print head makes a horizontal pass, it prints a pattern
of dots. To print figures taller than 7 or 8 dots, the print head must
make more than one pass. Each pass of the print head contains one
piece of
the
total pattern, which can be as tall or short as you desire.
You don’t
have
to use the whole page or even an entire line for your
graphics figures. In fact, you can use as little or as much space as you
like for a figure-and put it anywhere on the page.
Graphics Mode
The command to enter the Graphics mode is quite different from
the
other commands covered so far in this manual. For graphics, you
must specify not only that you want to use graphics mode, but also in
what density and for how many columns.
There are two graphics densities, single and double. The format for
entering Single-Density Graphics mode is:
LPRINT CHR$(27)"K"CHR$(n
1
) CHR$(n
2
);
The
CHR$(27)"K"
specifies Single-Density Graphics, and the two
numbers (n
1
and n
2
) determine the number of columns reserved for
graphics. The format is the same as above for Double-Density, except
you use
CHR$(27)"L".
Column reservation numbers
The graphics mode requires two numbers to specify how many
columns of graphics you want because the CHR$ function in BASIC is
limited to the numbers between 0 and
255.
Since you can specify
480
dot positions in Single-Density and
960
in Double-Density, you need
more than one CHR$ number. Therefore, the Graphics mode com-
mand is designed to use two CHR$ numbers for reserving columns,
and you must supply two numbers even if you only need one.
The first number that you specify (n
1
) indicates a number of
columns
(0-255).
A
255
in
that
position says “reserve
255
columns for
graphics.” If you don’t need more than 255 columns, you use a 0 for
n
2
.
To reserve more than
255
columns for graphics, the second number
(n,) must be greater than 0. But n
2
does not represent a number of
single dots; it represents a number of groups, each of which contains
256
dots. Using a
1
in the second slot means reserve
1
group of
256
dots plus whatever is in the first slot. For Double-Density Graphics,
