Pong clone identification

[Yoruk]

Hello there,

 

I just bought this TTL-chips only arcade pcb. It looks like a pong bootleg, but unfortunately I didn't manage to identify it. There is a weird female edge connector on a side, I absolutely don't know what it could be.

 

It was easy to identify the +5 and ground pads on the main edge connector, so I may be able to try powering it up. I don't think that a +12v is necessary, but I remember that some old pong boards have an external reset circuit...

 

Any idea someone ?

 

Thanks !