Very interesting. Has anyone updated with an answer? Can someone ask him to open it up and post pictures of the board? That should very quickly identify its general purpose.
It's got the 56k modem chip in it, which is strange, since the Japanese modems were normally 33.6k - it's hard to tell because the traces run underneath the chip, but my guess is that it might be wired to the aux audio pins on the modem chip - especially since there is that L6 common mode choke on the board, which looks a bit big for digital signals.
My guess is that the USB connector is used for interfacing with the serial interface of the modem chip (in this case we should find on the other side of the modem a usb-232 chip). Another guess is that the usb is used only for powering the unit so you can check exactly the power consumption of the 56k version. According to segaretro there were "different minor revisions dictating whether the power should be drawn from the console or through the phone line". This could be usedto test those configurations.
well the only thing i can help with is i'm pretty sure it says: HOTEISON #7 hoteison is a name, and apparently a "god of abundance" uses this name, but there's listings for cold weather motorcycle grips with the brand name "hoteison" on japanese sites. that's all i've been able to find out, perhaps the guy who made this went by the alias "hoteison" and this is prototype #7
I also tried to see what "Hanimaru" meant the other day when taking a look at this topic, I know "Maru" means "Ship" in Japanese, but I think maybe this is just a regular name as it didn't come up in any translators.
