Ring, ring... Terebikko calling!

2020-11-22 - Reading time: 4 minutes

So, a couple weeks ago I was watching this video tribute to Super Mario World's 30th anniversary.

At around the 17:20 mark, in the middle of talking about various tie-in products to promote the game, it brings up Mario & Yoshi's Adventure Land. A one-episode animated movie that follows Mario and Luigi through, essentially, the events of Super Mario World.

What makes it unique is that it this is a "VCR game" of sorts that uses the Terebikko: an interactive 'quiz' device that mimics a telephone. Mario calls you. The phone rings. You pick it up. He asks you a question that needs a 1, 2, 3, or 4 response. (Or red, green, yellow, blue.)

You press the answer within the allotted time, and you get a response. (Near I can tell, it mutes the phone for the inappropriate response, but that's something we're going to find out definitively.)

And it's more than just Mario. There's a whole catalog of videos made for it in Japan, including Dragon Ball Z and Sailor Moon.

I found it all oddly fascinating. And my curiosity started to kick in. It seemed so simple, but it was a clever idea. I loaded the audio into Audacity and realized I could make out binary... uh oh.

See, one of the things I've always had an interest in, but never got a chance to try was demodulation of a digital signal from an audio file. Like the screeching of a modem, or a game loaded off an audio tape into a ZX Spectrum. That kind of thing. This seemed like the perfect on-ramp for it.

With very little actual information online, this also seemed like a perfect reverse engineering project in general.

I found out they released a version of this in the United States in 1989 under the Mattel label, a year after it's debut in Japan from Bandai, and... I found one on eBay for under $20 shipped. 😎

So now I'm, seemingly, irrevocably committed to this project, now that money is involved. 😏

Here's what I'm planning. I've already spent a couple days dicking around and have a stack of notes. I'm hoping to get at least several decent blog posts out of this adventure:

My Goals for this Project!

Primary

• Reverse engineer the digital protocol used, as much as possible
• Create a real time decoder for it
• Create a tool to generate the codes, so people can create their own, new videos

Secondary

• Do a complete tear-down of the actual device with high res screencaps of the internals (I believe both US and JP versions are identical -- the case and operation certainly is, and the videos are all compatible with each other's versions). Just totally document the hell out of it. Get it all onto Github and Archive.org for safe keeping.

Nice to Have

• Possibly integrate the decoder into a software emulator/video player as an all-in-one playback app. (How hard are VLC plugins to write...? 🤔)

That last one is unlikely, but hey, if I haven't burned myself out on the entire thing by that point, who knows?