With this adapter:
You can connect a mouse and a Joystick on the same 9pin port of Amiga/ Atari ST and automatically activate them using either Left mouse button or Joystick's First Fire button !
A few words about circuit: Adapter uses a 74LS126 Quad 3state buffer, to isolate mouse movement when joystick fire button is pressed, and re-activate it ,when Left mouse button is pressed.
Practically, mouse port is isolated, whenever Joystick is used, where joystick port, is always active, as it does not interferes with mouse signals (all Joystick movement+fire signals are open switches, when not used) .
Monitoring of mouse/joy buttons and activation/deactivation of Quad 3-state buffer, is done with a small 10F200 PIC microcontroller.
Anyone interested, please contact at: ikonsgr745@hotmail.com