Sega Master System / Mark III / Game Gear
6666666 as password to start the game with more then $900000.
On the title screen, select Training Mode (the second option) by pressing or . Before the screen fades to black, hold +. When the training mode screen appears, release the buttons. There will be no game name in the middle of the screen. Without pressing the D-pad, press to enter the Sound Test.
See the main page for Gamble Panic (ぎゃんぶるぱにっく)