Commodore Amiga Hardware Reference Manual page 233

Table 8-3: Typical Controller COllllectiol1l:s
Mouse,
Trackball,
Proportional
X- Y Variable
Driving Controller
Proportional
Pin
Joystick Controller (Pair)
Joystick
1
Forward*
V-pulse (unused)
(unused)
2 Back*
H-pulse
(unused) (unused)
3 Left*
VQ-pulse Left button
Button 1
4
Right*
HQ-pulse Right button
Button 2
5
(unused)
Button (3) Right POT
POT X
(if used)
6
Button(l) Button(!)
(unused) (unused)
7
+5V +5V
+5V +5V
8
GNp
GND
GND GND
9 Button(2)
Button(2) Left POT POTY
(if used)
An asterisk (*) at the end of a name indicates active low.
Reading Proportional Controller Buttons
For the two-control paddle controllers, the left and right joystick inputs serve as the fire
buttons for the left and right controllers.
Interpreting Proportional Controller Position
Interpreting the position of the controller requires some preliminary work. This is an
activity normally done during the vertical blanking interval (and is part of the operating
system function).
During vertical blanking, you write a value into an address called POTGO. For a stan-
dard X-Y joystick, this value is hex 0001. Writing to this register starts the operation of
some special hardware that reads the potentiometer values and sets the values contained
in the POT registers (described below) to zero.
222 Interface Hardware