Star Micronics SR-10/I5 user manual

Figure 9-5. Later in this chapter we’ll use this character to create a small graph.)

You’ll notice that Figure 9-4 includes a lot of information around the grid. Don’t be intimidated; we’ll explain each item as we come to it in our discussion of defining and actually printing download characters. You may have noticed another difference between this grid and the one shown in Figure 9-3: it’s only eight boxes high. Which leads us to...

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ASCII Code

Descender

Start column

End column

16

M, = Descender • 128 + (Start • 16) + End

Wal

Figure 9-4.Use this grid (or one similar to it) to define your own characters.

nRule 1: Download characters are eight dots high

As you noticed in Figure 9-2, capital letters, most lowercase letters, and most special characters use only the top seven pins of the printhead. Download characters can go one better: they can use as many as eight of the nine wires in the print head. So our grid is eight dots high.

It’s also possible to use the bottom eight pins, just as the “g”, “‘9, “ ,,

1, P, “q”, and “y” of the standard character sets do. These are called descenders (because the bottom of the character de- scends below the baseline of the rest of the characters).

One bit in the download character definition command is used to tell SR- IO/ 15 whether a character is to be treated as a descender or not. We’ll get to the command in due time. For now, if your

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