Microscopic line spacing
There is also a way to space at smaller intervals than 72nds. Using a
CHR$(27)“3” will set the spacing to increments of 216th of an inch;
l/216-inch is one-third the distance between the pins of the print head
(center to center). That means the printer can position a specific line
one-third of a dot lower than the previous line. In fact, that’s exactly
how the Double-Strike Mode operates. One word of caution. As you
can imagine, total accuracy is not guaranteed for such fine settings as
l/216- and 2/216-inch.
You specify this finer line spacing in much the same way as you did
the variable line spacing that we showed above with CHR$(27) “A”.
The format is CHR$(27)“3”CHR$(n), where n can range from zero to
255. Here’s an example using the l/216-inch line spacing five times.
Change lines 10 and 30 to read:
10 LPRINT CHR$(27)"3"CHR$(l)
30 LPRINT "ABCDEF"
These letters are very heavy looking. To carry this idea to an extreme,
increase the upper limit of the loop to 10 or 15.
The ability to adjust line spacing in increments of l/216-inch gives
you tremendous control in your vertical formatting. You can use this
control to fine-tune your graphics printouts. If the 7-dot line spacing
leaves gaps in the figures, just tighten it up by changing it to 6-2/3-dot
(20/216-inch):
CHR$(27)"3"CHR$(20)
We’ll use this technique in a later chapter.
Line Feeds
Besides being able to change the size of line spaces, you can change
other aspects of a line feed. You can send it immediately and for one
line only, or you can send it as above, as a continuous feature. And if
you are using an FX-80, you can send a reverse line feed to make the
print head move back up the page.
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