How to make a four player adapter
Several games on the ST (Gauntlet 2, Dynablaster, Leathernecks, Kick Off 2) support up to four players at the same time.
To achieve this, joysticks 1 & 2 plug into the joystick and mouse ports as normal, joysticks 3 & 4 plug into a special adapter that plugs into the printer port on the back of the ST.
The method for making the adapter can be found in ST Format, issue 18, p184