Popeye Update

I am sorry I am running late with the beta release but I'm happy to announce that I made a critical step forward this week:

Popeye has a lot of encryption and obfuscation on the board. It is impossible to get it right just with the schematics. However, Scralings had found a report on the obfuscated logic here and MAME had the encryption implemented so I was confident to get it through. But after a lot of work there was no way to get the background display and scroll correctly. Remember that post I wrote about improving the simulation flow? I was trying to understand what was going on.

I even got the original author of the obfuscation report to make some measurements on his arcade board but they didn't make sense. He told me the board was broken so maybe his problem was in the same place I was interested in.

At that point, I knew the background hardware and encryption by heart and I thought that something didn't quite make sense. The encryption device 3E, in the centre of the image, was reported to be just buffers. But I had a hunch of it being inverters. I changed it and voilà, the background came out perfect!

Status:
Game logic   OK
Sound            OK
Text                OK
Background OK
Sprites          WIP