Commodore Amiga A2000 - Figure 8-3 Joystick to Counter Connections

Digital joystick switches are of the normally open type. When the switches are pressed,
the input line is shorted to ground. An open switch reads as "1", a closed switch as "0".
Reading the joystick input data logic states is not so simple, however, because the data
registers for the joysticks are the same as the counters that are used for the mouse or
trackball controllers.
The joystick registers are named JOY0DAT and JOY1DAT.
Table 8-2 shows how to interpret the data once you have read it from these registers. The
true logic state of the switch data in these registers is "1 = switch closed."
_________________
This is the \ 1 2 3 4 5 /
way the pins \ 6 7 8 9 /
are numbered! \___________/
_________________ _________________
PORT 1 \ o o o o o / PORT 2 \ o o o o o /
(mouse) \| o| o| o| o / \ o o o o /
|__|__|__|__/ \___________/
| | | |
| | | | JOY1DAT
| | | | DFF00C
| | | | is wired similary
| | | |
| | | |________________
| |__|_________________ |
|__ | | |
| | _______|_|
_________|__| | | |
| | | | | |
| \-----/ | \-----/
__|__ |
\ / \-----/ __|__ \-----/
\ / | | \ / | |
V | | \ / | |
| \___/ V \___/
|____ | | |
| | | __|
| | | |
_______|______|__________|______|______________
| | |
| MOUSE 0 | MOUSE 0 |
| Y Counter | X Counter |
| | |
|__|__|__|__|__|__|__|__|__|__|__|__|__|__|__|__|
Figure 8-2-1: Mouse Counters.
- Interface Hardware 227 -