Daiku no Gen-san - Robot Teikoku no Yabou [Model DMG-D9J]

Cheat mode:
To enable the cheat mode, at the title screen, press Up, A, Down, B, Left, Right, Left, Right, B, A. A sound will confirm correct code entry. There are several options available now.
At the title screen, press and hold Start. While holding it, wait for the PUSH START message stops to fade in and out, then press B button a number of times corresponding to the Stage or substage number including bosses, up to 13. Every time you press the B you'll hear a sound. Release, Start to begin the game from the selected Stage.
During the game, press and hold Start. While holding it, wait for the pause jingle is over, then enter one of the sequences from the table below to get the corresponding effect. Every time you press the correct button, you'll hear the same sound effect as on the title screen when cheat is activated.
Also, you can use now Select to freeze the game as an alternative to the pause mode.
Right, Left, Right, Left, Down, Down, Up, Up, A, B - Refill lives.
Up, Down, Up, Down - Instant Game over.