Mega Drive - Sonic 3 - Level Select
Up, Up, Down, Down, Up, Up, Up, Up
Execute code after SEGA but as Sonic first appears for the intro animation. You'll hear a mono right speaker 'ring' collection sound if executed properly. For anyone struggling, it's so much easier to pop Sonic 3 into Sonic & Knuckles to do the Angel Island and Mushroom Hill versions of the level select / debug. Let's face it, it's better as S3 & K anyway!
Captured from real hardware: SEGA Mega Drive Mk1 (PAL @ 50Hz)