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142
Radix User's Manual
Specifying the graphics data
Now that we've told Radix how much data to expect, we bet-
ter figure out how to send that information! Just as you do with
download characters, with dot graphics you have control over the
firing of every single pin on Radix's print head. In Figure 12-1, you
can see that we've labeled each pin on the print head with a num-
ber, as we did with download characters (you should note one
important difference: this time the top pin has the highest value;
for download character definitions it is the bottom pin). And spec-
ifying pins to fire is done in the same way: to fire the second pin
from the top, for instance, send a CHR$(64). Firing several pins at
once is done in a similar fashion. For example, to print the first,
third, and fourth dots, add their values
(128
+
32
+
16)
to send this
total:
CHR$(176).
This is one byte of graphics data; it would
replace
ml
in our format statement on page
140.
_
I I
8
6
4
-
Figure 12-1. Starting with the most @@cant
bit at the top, each pin of the print
head is assigned a value which is a power of two. Note that for T-bit computers, the
top pin has a value of 64, and the bottom two pins are unused.
-
A short program should demonstrate how to implement the
graphics command. The program below gave us this printout:
..__. . ..-"'"---" ____
--
._,......_ I---
_,__- -...-
._..._.__,
18 'Demo bit graphics.
2g
PI =
3.14159
30 WID = 100
-
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