Yeah, Simultano driver in 1 day is fast. It resembles Stratos a lot, so I could copy-paste half of the driver. And the SVG screen was already done too.

Writing an emulator, part of it is from experience I guess? If there are no schematics available, what you do is get the facts from PCB photos. Then determine the I/O by looking at read/write patterns while running the game live, using MAME's debugger.