The Nintendo DS design resembles that of the multi-screen games from the Game & Watch line, such as Donkey Kong and Zelda, which was also made by Nintendo. The lower display of the Nintendo DS is overlaid with a resistive touchscreen designed to accept input from the included stylus, the user's fingers, or a curved plastic tab attached to the optional wrist strap. The touchscreen lets users interact with in-game elements more directly than by pressing buttons; for example, in the included chatting software, PictoChat, the stylus is used to write messages or draw. The handheld features four lettered buttons (X, Y, A, B), a directional pad, and Start, Select, and Power buttons. On the top of the device are two shoulder buttons, a game card slot, a stylus holder and a power cable input. The bottom features the Game Boy Advance game card slot. The overall button layout resembles that of the Super Nintendo Entertainment System controller. When using backward compatibility mode on the DS, buttons X and Y and the touchscreen are not used as the Game Boy Advance line of systems do not feature these controls. It also has stereo speakers providing virtual surround sound (depending on the software) located on either side of the upper display screen. This was a first for a Nintendo handheld, as the Game Boy line of systems had only supported stereo sound through the use of headphones or external speakers. A built-in microphone is located below the left side of the bottom screen. It has See more