From the beginning, we wanted to make Bubble Bobble: Lost Cave run on the original Bubble Bobble PCB. And we succeeded in doing it.
Then, we realized that the number of people who could benefit from this achievement was quite low. Bubble Bobble original PCBs are rare and expensive – so rare and expensive that even the Lost Cave team does not own one. And it’s not just that. Having an original Bubble Bobble PCB, would you put your hands on it, and ROM-swap the ROMs with the Lost Cave ones? Hmm, maybe yes, maybe not.
Some months after the release of Lost Cave, we started to think about running it on a bootleg Bobble Bobble PCB. Problem is, that the Bobble Bobble PCBs does not behave exactly in the same way Bubble Bobble does – there are some not so slight changes in gameplay and way more slowdowns than in the original game. So, the bootleg code from Bobble Bobble is not a good base for Lost Cave.
Then, we found that ArcadeOtaku forum user joaoljr did something wonderful – he rewrote the bootleg MCU emulation in order to obtain a faithful Bubble Bobble behaviour even on the Bobble Bobble board! Yay! That was an important inspiration for us. We could not use his so-called “Redux” version as a base, though, because Lost Cave, in turn, runs even more custom code over the regular Bubble Bobble code. We needed a super-optimized MCU emulation code, in order to perfectly transform Bobble Bobble in Bubble Bobble, and then, on top of that, inject the Lost Cave code into it. Feeling lost in a sea of bubbles? We felt the same way.
After studying the bootleg code, Aladar managed to squeeze everything onto the bootleg PCB. One of the important steps in doing it was to optimize the original Lost Cave code running on the original Bubble Bobble. That’s right – the soon-to-be-released Lost Cave 1.2 revision will work even better, with less slowdowns, even on an original PCB or in the MAME version of your choice. There are also some minor gameplay balance fixes, based upon one year of user feedback. Hopefully this will be the final Lost Cave version, so we can get on to Rainbow Islands Gaiden. Just kidding.
Bubble Bobble Lost Cave 1.2 will be released here on December the 11th, 2013.
Here’s how we made Lost Cave run on a bootleg Bubble Bobble PCB!
1. Buy a Bobble Bobble PCB on Ebay. Not the one with the 68705 microcontroller. The other one. The one which needs a separate JAMMA connector, typically.
2. Buy a EPROM reader/writer. It’s something Chinese Ebay shops really want to sell to you. Be sure it’s compatible with the 27256 EPROM type. Which is most likely. Mak esure they send you the correct merchandise. I asked for a chip extractor thing and they gave me a rubber pencil. Really.
3. Buy some EPROMS. More than you actually need. Because used EPROMS not always work. And it’s quite unlikely to find 27256 new EPROMS nowadays. On Ebay, you’ll find used ones.
4. Buy an EPROM UV eraser. The good thing is that if nasty things happen while you try to burn EPROMS, you can (almost) always erase them in 15 minutes and try to rewrite them.
5. Once you’ve burned successfully all the EPROMS, mount them on the Bobble Bobble PCB. It’s a plain ROM swap, just as for the original PCB. Put them on the board in correct order, be careful, et cetera.
6. Aww, I told you to be careful! Old, poorly made bootleg board sometimes have sloppy chip sockets…
7. And that’s it! It works! Ehr, I notice that it still says 2012. Need to change that. Fast.