Commodore Amiga A2000 - Table 8-3 Interpreting Data from JOY0 DAT and JOY1 DAT

Table 8-3: Interpreting Data from JOY0DAT and JOY1DAT
Data Bit Interpretation
1 True logic state of "right" switch.
9 True logic state of "left" switch.
1 (XOR) 0 You must calculate the exclusive-or of bits 1 and 0
to obtain the logic state of the "back" switch.
9 (XOR) 8 You must calculate the exclusive-or of bits 9 and 8
to obtain the logic state of the "forward" switch.
The fire buttons for ports 0 and 1 are connected to bits 6 and 7 of CIAAPRA ($BFE001). A
0 here indicates the switch is closed.
Some, but not all, joysticks have a second button. We encourage the use of this button if
the function the button controls is duplicated via the keyboard or another mechanism.
This button may be read in the same manner as the right mouse button.
READING PROPORTIONAL CONTROLLERS
Each of the game controller ports can handle two variable-resistance input devices, also
known as proportional input devices. This section describes how the positions of the
proportional input devices can be determined. There are two common types of
proportional controllers: the "paddle" controller pair and the X-Y proportional joystick. A
paddle controller pair consists of two individual enclosures, each containing a single
resistor and fire-button and each connected to a common controller port input connector.
Typical connections are shown in Figure 8-3.
- 228 Interface Hardware -