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We'll label these top 8 pins as follows:
128 - 0
TOP
64 - o
32 - o
16 - o
8 - O
4 - o
2 - o
BOTTOM
l - o
o
(Ninth pin not used)
From now on we will refer to the second pin (pin 1 above) as the "bottom" pin
when using graphics.
Why not label them 1, 2, 3, . . . 8 etc? Well, the numbers shown are the actual
ASCII numbers that fire the respective pins. CHR$ (128) fires the top pin, while
CHR$ (1) k-es the bottom one. CHR$ (7) fires the bottom three (4+2+1). Just
no way to escape Binary math when dealing with computers, is there?
Add these lines:
20 FOR P = 1 TO
PRINT CHR$ (l);
30
40 NEXT P
50 PRINT
59 PR #0
and RUN.
Sure enough, fifty little dots. CHR$ (1) in line 30 caused the bottom pin to fire.
The semicolon suppressed the line feeds. The FOR-NEXT loop fired the
bottom pin 50 times.
Change line 30 to:
PRINT CHR$ (127);
30
and RUN.
5 0
(Apple)
Figure 5-1
Graphtrax II
43
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