Testing a "Super 4 game in 1" cartridge

I recently obtained a batch of retro games and've been testing everything prior to putting them up for sale.
Among these were two bootleg GB cartridges, one of them being a multi-game card.

On the cover there are 4 games mentioned:
- Motocross Maniacs
- Dr Mario
- Klax
- some tank game, anybody know which one?














As you can see, it looks clean. It works perfectly, bar the fact that I DO NOT know how to select the other games.
By default, Dr Mario starts up.
I had Klax boot for a couple of times, but I can't seem to work out what button combination or whatever it was...
If anybody knows if these types of games have a standard button press/hold/combination at boot or whatever, I can figure out how to select the other games to test.

Thanks.

 

Maybe try holding Select upon boot.

 

I'll bet the tank game is Battle City, maybe under a different name, since that seems to be on every GB (and NES) multicart.

 

...as I already tested different button holds on power up/Nintendo chime, I doubted it was one of these.
The 4th game is indeed Battle City, as 7Force suggested.
The game selection mode is again, indeed by powering off/on really fast as 7Force suggested in the chat.
Thanks for that

Game boot order is this as follows: Dr Mario/KLAX/Battle City/Motocross Mayhem

Any idea what these bootlegs go for? As I'll be putting this one and Turtles (HK bootleg/Japanese version) up for sale soonish.

 

Hardly anything...

 

I remember one of those things. My relatives had one with a tactile switch in the back and it went from Ghost and Goblins to the Great Battle SD.

 

Sounds like they copied the design Atari used in their official 32-in-1 for the 2600 system. No way to change game other than powering off/on and almost always get the one same game every time. Awful design.

That chip is a 7 bit binary counter being used as bank selector, you could try ripping the chip out, install a 2 position DIP switch, one end to pin 11 and 12 and dd a 10k pull up resistor from that 2 to VCC source, other end of the DIP switch to ground source. You will always get the game you want by setting the switch. It's what I did to my 32-in-1 long ago. Easy hack once you figure it out.

 

Well, it works as it should: no problems switching games, so I'm going to leave it alone.
Should I post the Turtles' innards here too, just as archiving purpose?