Thanks, Mike!
I finally managed to get the eprom working in my Delta-1!
Only had to invert the CE2 signal. Luckily there was a NOR 4001 already present which inverted it for the RAM 2111 chips. (Chip Selects are always confusing when replacing mask-roms with eproms..)
Sorry if I rushed into wrong conclusions about MAME, really nothing wrong there, except I was bewildered by the different moves compared to the real Delta-1. (I haven't played much on the original, since I got it only yesterday
) I believe the uninitialized (randomized) RAM in MAME lets it play other moves.
Some pictures for those who want to replicate my hack. Be careful with the screws, I broke the plastic holders.
Now I will play some games..
EDIT: After playing some games, there's still something wrong, pieces get lost or appear in RAM.. Ich muss nochmals über die Bücher