That's actually a good theory. I wonder if it would make a difference if one were to use a modern switcher, rather than the Nintendo PS?
I would be very interested in the results from a test like this.
I don't actually have a DK PS. I use a modern power supply on my test bench.
I don't have a D2K board either, but I did test the concept of it's stacking functionality by stacking two Remix boards on top of each other and testing that the game switcher did switch from the top board down to the middle board.
Also John, you mentioned a Reset header on the DK PCB. I haven't pulled out my PCB yet (moving the cab is a pain), but looking at pics, I don't see it. Could you perhaps post a pic of where that header is?
I'm going to take a photo and post it up tomorrow.
I'm also curious how the heck you're able to get Free Play to work when running from the PCB ROMs, though I did notice that the green "CREDIT" text is not there at all when the PCB is set to Free Play.
This is almost at the level of a magic trick, actually.
The Remix board has a microcontroller on it, essentially a whole new CPU that is capable of performing sleight of hand operations onto the Z80.
I've programmed the microcontroller to monitor the Z80's data and address bus, and when the Z80 is reading certain addresses, say to check for coins... it is able to substitute new values onto the bus. Essentially we're convincing the Z80 that something happened when it didn't, or vice versa.
It would have been too much trouble to hack in something entirely new, like a text indicator saying "FREE PLAY"... well, it would be possible, but the microcontroller would have to do an awful lot of sleight of hand to pull that off, so it simply makes the Z80 skip the credits display instead.
The really cool thing is that free play will still work no matter which version of DK ROMs you have on your PCB.
The other thing I wanted to mention is my concern that somebody will dump your game from the Remix PCB and it will be MAMEd before you intend it to be. I've thought about it some more and for a few reasons I kinda like that it isn't MAMEd yet. As for you, once it's out on MAME, it can never go back, so until then you have more options and control over it. I don't know enough about your hardware setup to know whether it's even possible to dump the game, so maybe you're safe for now.
This is a big concern for me. I was just about at the point of breaking even on the initial costs of making the boards, but I'm in the process of doing something expensive that's setting that back a bit. (The big reveal of what and why will come in about 2 weeks, I think. But it's for good reasons, and it'll benefit everyone who has a Remix board.)
Technically, it is possible to dump the code if someone were really determined. A full and proper MAME emulation, though would probably be a bit of a challenge because of the nature of the dual processor interaction so I'm hoping that buys me a bit of a grace period.
But I agree, I think it's nice that you have to play the game for real, on real hardware, without save states, without tool assists or program code analysis or whatnot. This makes is a little more special, more mystical.
And I think the hardware is cool. There is actually a lot of untapped potential in that hardware. The way the free-play function for DK works is just a hint of what's possible. It's a shame I couldn't spend forever taking full advantage of it, but maybe some future revision of the board firmware will open up additional special features.
