Often a figure needs more than half a line. 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 num-
ber of groups, each of which contains 256 dots. Using a 1 in the second
slot means “reserve one group of 256 dots plus whatever is in the first
slot.” A 2 in that spot means “reserve two groups of 256 dots (512) plus
. . .
” and so on-up to 7 times 256 (or 1792) dots on the FX-80 and up
to
12
times 256 (or 3072) on the FX-100.
Actually, the FX-80 will accept numbers larger than 7 for n
2
, but it is
pointless to send them because the printer treats them as modulo 8.
That is, 8 works the same as 0, 9 as 1, 10 as 2, etc.
Similarly, the FX-100 treats numbers above 12 as modulo 13. The
maximum number of dots you can reserve on the FX-80, then, is:
CHR$(27)"K"CHR$(255)CHR$(7);
which is 255 dots plus 7 times 256 dots . . . for a total of 2047 dots per
row. On the FX-100, you can reserve 255 plus 12 times 256 . . . for a
total of 3327 dots per row.
But on a Single-Density print line you can only fit 480 dots.
For now, we’ll stick with Single-Density, which means that we
won’t use numbers over 480. Later we’ll see that the FX does have
Graphics Modes of greater density.
Some systems, such as those for the IBM-PC and the Epson QX-10,
also require WIDTH statements for longer lines. See your system doc-
umentation.
Pin Labels
Once you put the printer into Graphics Mode, your next step is to
tell the print head which pins to fire at each new position. You do this
by sending numbers via the CHR$ function. Each number that you
send represents a unique combination of pins.
You might expect that the eight pins would be numbered 1 through
8 (as they are in Figure 10-1). But that won’t work because you are
going to send one number to represent all the pins to fire in one col-
umn. Using the 1-through-8 system, you would send such a total as 10
and the FX wouldn’t know if this meant pins 4 and 6 or pins 2,3, and 5.
135
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