The DK'tronics Joystick interface plugs into the Expansion port and maps itself to two locations in Page 3.
|Page 3 Address||Joystick|
|$0310||Port 1 (Left)|
|$0320||Port 2 (Right)|
This unfortunately prohibits the interface to be used with the Microdisc Disk Interface since this maps to the same address space.
Note all drivers use a common label list that is found here generic_joystick_drivers
The following code provides a standard output for detection of joystick movements in your own code.
GenericReadDKTronics LDX dkt_LeftJoy JSR ReformatJoystickBits STA joy_Left LDX dkt_RightJoy JSR ReformatJoystickBits STA joy_Right RTS
temp01 .byt 0
ReformatJoystickBits ;Reformat Fire TXA AND #4 ASL ASL ASL STA temp01 ;Reformat Left/Right TXA AND #24 LSR LSR LSR ORA temp01 STA temp01 ;Reformat Up TXA AND #1 ASL ASL ASL ASL ORA temp01 STA temp01 ;Reformat Down TXA AND #2 ASL ASL ORA temp01 RTS
This provides the following bits to joystick movements.
1) It is unknown if the DK'tronics interface Joystick ports supported autofire.