Sega Master System / Mark III / Game Gear
|Master System Control Pad (code 3020)|
|Master System Control Stick (code 3060)|
The joypad is the standard peripheral supplied with (or built in to) the Sega 8-bit games systems. It is compatible with Atari, C64 and, to a slightly lesser extent, Mega Drive/Genesis hardware.
Sega also released a digital joystick using the same interface, and some third-party controllers were also released.
The TR line is configured as an input to the system.
Because the controller ports are active-low, a
1 in the corresponding port register signifies "not pressed" and a
0 "pressed". This is achieved in hardware by leaving lines unconnected when not pressed, and connecting them to Gnd when pressed.
Button 1 is to the left of button 2. Button 1 is also labelled "START" on the Master System, and is the expected input when a game prompts the user to "press start", although a better interface (for software running on the system) would be to accept either button.