Stella DS, an Atari 2600 emulator for the Nintendo DS, version 0.5.5. The controls:

– The directional plus pad controls the joystick.
– The A button is the joystick fire button.
– The B button swaps the game's current LCD screen.
– L and R control the system select/reset switches.

Changes in this release include: “

– Press START during a game to go back to the menu and play a new ROM.