I believe The Lost Vikings never worked in DE1 port, or at least I don't remember it working. I believe it's due to TG68 since it works on the original Minimig 1.1 board without any problems. Looking forward to see the new sigma-delta! Both fronts are very exciting!
I was reading this post, and was under the impression that at some point, Lost Vikings did work on the DE1. Too bad, that would probably make it a much easier fix
EDIT somehow the link to the post was lost, there you mentioned that Lost Vikings used to work, here it is: viewtopic.php?f=3&t=296
I can't get the game to even start, the floppy versions I have just silently stop in DOS window after loader/crackthrough, and the Whdload version reports some access violation error before finishing loading.