Fire Game Converter: how exactly does it work?

Hello,
I'm into making repro carts for myself and to test them, if I don't already have a soldered CIC chip inside, I use the Fire Game Converter like this one:to use the CIC chip from the cart sitting on the back. The following is a Demon's Crest cart with no CIC chip installed and a PAL Jurassic Park on the back used to provide the CIC chip.The cart works correctly except that after defeating the first boss, the software region protection kicks in with this message:Messages like this tipically happen (at least to my experience) when there's a mismatch between the expected refresh rate and the current one, so that a 60hz NTSC game won't work in a 50hz PAL console and viceversa.

Here's some facts:

• I can trigger the same screen on bsnes if I run this PAL rom and set the console region to NTSC.
• I double checked the rom using ucon and it says Europe,Asia,Oceania PAL.
• Rom checksum is C8386172, the same I found on the Internet as a good PAL dump.
• The Cart on the back uses a superCIC, but the same problem arises with an original SNES game with a legit PAL CIC.
• I have this adapter since almost 20 years now and I remember that a similar message appeared on (if I remember correctly) Super Mario All Star PAL if used through that adapter, so basically every PAL game works correctly inside my SNES, but this very same PAL game refuses to work with the adapter even if on the back a PAL cart is provided

I then opened the Fire Adapter and found that:

• The only lines used by the back cart, apart Vcc and GND, are the CIC lines: pins 24,25,55,56. /CART and /RD are held HIGH.
• On top of some lines there's a tibpal16l8-25cn, a Programmable Array Logic.
• The yellow wires connect to pin 20 (Vcc) and pin 19 (O)

FrontBackNow, obiously this chip is doing something and what it does depends on how it has been programmed.
I'd like not to desolder it to find out it's truth table, but at this point my 2 questions are:

Does somebody know what is this chip doing, at least on a higher level?
Couldn't the adapter just route the CIC tracks from the back cart? Doing so would be electrically equivalent as having the "donor" CIC directly on the game cart, so why the need of that tibpal16l8 in the first place?
My only guess is that it is used for carts using chips like the SA-1 which provides an integrated CIC chip and I belive it may work in a slightly different way.

Tibpal16L8 datasheet

Statistics: Posted by MastErAldo — Tue Sep 24, 2024 1:09 pm — Replies 0 — Views 43

---