Star Micronics Radix User Manual page 154

140
Radix User's Manual
Comparing Dot Graphics with Download
Characters
A good understanding of dot graphics requires an under-
standing of how dot matrix printers work; you may want to
review the first few pages of Chapter 11. The principles for dot
graphics are the same as those for download characters.
There are some differences in the way they are implemented
however. While download commands can be used to define a
character between four and eleven columns of dots wide, dot
graphics commands can be used to define a shape as narrow as
one column of dots wide or as wide as 3264 dots on a Radix-15!
There is no "descender data" with dot graphics; graphics
images are always printed with the top seven or eight pins of the
print head, depending on whether you have a 7-bit or 8-bit inter-
face (if you're not sure which type of interface your computer has,
check the appendix for your computer).
So when do you use graphics and when do you use download
characters? Practically anything you can do with graphics you
can do with download characters, and vice versa. A clever pro-
grammer could actually plot a mathematical curve using
download characters or use strings of graphics data as user-
defined characters. But why do it the hard way? There are several
instances when dot graphics is clearly the best way to approach
the problem:
l
If the graphic image to be printed is wider than 11 dots or higher
than 7 dots
l
If an image is to be printed just one time, as opposed to a fre-
quently used "text" character
l
If you want higher resolution (Radix can print as many as 240
dots per inch in dot graphics mode; text mode, which includes
download characters, prints 60 dots per inch)
-
-
Using the Dot Graphics Commands
The command to print normal density (60 dots per inch hori-
zontal; 72 dots per inch vertical) dot graphics uses this format:
(ESC) **Kff nl n2 ml m2. . .