SpritesMind.Net

Game Toshokan seems to support some unknown peripheral in port 3 besides the modem, although in practice it can't be used since the program will halt if it can't find a modem there. The relevant subroutines seem to be pretty much intact though.

I don't have much time to document this right now (nor do I really know what it does yet), but here are some notes in case somebody wants to keep researching:

$0053EE: detects what device is in port 3. It returns 0 if there's nothing supported, 1 for this unknown peripheral, 2 for the modem.
$00550A: reads a byte from the peripheral
$00555A: writes a byte into the peripheral

Will update this when I get more time, right now the laptop's battery is about to deplete =P

Can it be a sort of "custom" modem or cross cable hardware made by the game manufacturer ?

The final version of Game Toshokan won't boot if it's connected (it needs the Mega Modem or it'll complain). It could have been a fake "modem" for testing while it was being developed, though. An official protocol for a faster modem would be neat.

The other theory is that it could be the RAM drive mentioned in one of the addenums. I mean, the biggest issue with Game Toshokan is that it needed over 9 minutes on-line every time you wanted to start a game and that's assuming a 100% clean phone line (no wonder it failed), it'd only make sense if you could permanently save the games to avoid that load... which is when it struck me that it could have supported the floppy drive, and why I started looking into the code to see if any remainders are there (and then I find this instead).

Or it could be something we still aren't aware of.

Whatever, what it definitely is not:

• The keyboard, because a prerelease pic shows it connected in a joypad port
• The floppy drive, because it would have connected to the extension slot (the Sega CD one)