Control Pad (Master System)
From Sega Retro
The Master System Control Pad or Sega Control Pad (コントロールパッド) is the official controller which came packaged with Sega Master System consoles. The controller connects to the system via a DE-9 port, so it is also compatible with various other systems of the day including the Sega Mega Drive.
The control pad is very similar to the first generation of NES controllers, and all models contain a D-Pad and two buttons labeled and . Button also doubles up as a button, meaning it is only possible to pause a game by pressing the pause button on the console itself. As with the Sega Mark III, the D-Pad is a rounded square to avoid legal issues with Nintendo's patented cross-shaped design.
Several versions of the control pad exist exist: