Connecting an external serial modem to the Dreamcast?

[TapamN]

On Reddit, there was a post about a Crazy Taxi beta. After looking through the poster's website, I noticed something about a Sega tool for modifying and viewing the DC's internet settings. I was working on a program to view the contents of the DC's flash, and having that would help figure out a lot of currently undocumented parts stored in flash. The link was broken, but he was able to upload it again after I mentioned it.

Looking through what the program was displaying, I noticed that there was a setting for selecting between an external and internal modem, with UART settings listed underneath. (Screenshot here) It looks a lot like there is/was an option for having the DC use a external modem (presumably Hayes compatible) connected to the serial port, instead of the expansion port.

It seems unlikely that the option works. After all these years, no one has noticed this feature while reverse engineering different parts of the DC and its games? I think it's more likely just some leftover from before Sega finished developing the modem, and nothing really supports it. On the off chance anything does work, it's probably mostly untested and potentially buggy.

If it did work, it would be a huge improvement to the current DreamPi setup. You could just connect the serial port to a computer with a PPP emulator without needing any USB modem or dealing with line voltage. Both the Dreamcast and Raspberry Pi have 3.3v serial ports, so they could be directly connected. The host could skip dialing and just immediately say that it connected. A direct, digital connection between the DC and the host would have better latency than having to go between two modems. The program also lists higher baud rate options than possible over a phone line, up to 460800 baud.

Does anyone here know anything about this? I have a coder's cable, so I can try (at some point, maybe not right now) turning the option on to see if anything comes out of the serial port, if no one else has already done it.

[SEGA RPG FAN]

I know Dreamkey 3.0 has a serial port option for its internet setup. I've never heard of anyone trying it but I've always been curious.

[GIR]

It would be really cool to see this come to fruition if possible

[Wombat]

Keeping an eye on this, the Dreamcast scene just never gets boring. It's amazing to see how time after time new things come to light. Would be very cool if dial-up games work without modification with a serial modem.

[TapamN]

I know Dreamkey 3.0 has a serial port option for its internet setup. I've never heard of anyone trying it but I've always been curious.

Oh, I didn't know that.

The flash settings tool was in GDI format, and I don't have anyway to run GDIs on a real console. I tried extracting the 1ST_READ.BIN and used dcload to try to run it, but it didn't work. I thought about just writing a program with KOS to enable the external modem setting, but decided to burn a DreamKey 3 CDI image (I had trouble finding a non-GDI version online, but looking through an external hard drive, I found that I had downloaded a CDI at some point and kept it around) and use that to enable the serial port modem. Then I set my computer's serial port to 115200 baud (This was the default in the tool, and I know it works with my PC from using dcload-serial) and ran "cat /dev/ttyUSB0".

These are the results of what I tried. I had a BBA plugged in the entire time, unless otherwise noted. All games were US versions (except DreamKey) run from real GD-ROMs (except DreamKey and Propeller Arena).

• DreamKey 3 (PAL, burnt disc): It worked correctly! I was getting correct modem initialization attempts (Hayes "AT" command). The attached screenshot shows what I was receiving.
• Chu Chu Rocket: No activity when connecting in-game, with its web browser I received gibberish. Maybe the DC was using a different baud rate than 115200?
• Sonic Adventure Browser: Internet option was enabled, despite no modem. Trying to connect with the web browser just had it busy spin until I hit start and selected stop. PC didn't seem to receive anything.
• 4x4 Evolution: It was softlocking on the save select screen. Not sure if it had to do with the serial setting or what I had plugged in (mic, 4X memory card, keyboard, mouse). With only a VMU-less controller attached, I was able to try to connect. It immediately failed, with nothing on the PC.
• Ooga Booga: Immediately failed to connect, nothing on the PC.
• POD Speedzone: Tried to use BBA. With BBA unplugged, the Network option was disabled.
• Starlancer: Immediately failed to connect, nothing on the PC.
• Crazy Taxi 2: Browser said connection failed, no activity.
• Daytona USA 2001: Net Battle and Homepage options disabled.
• Metropolis Street Racer Browser: I was allowed to start the browser, but got nothing when trying to connect.
• F355 Challenge: (I had the BBA disconnected here) I was allowed to access Network Race and Homepage options. Both failed with nothing on the serial.
• Shenmue Passport: "Modem is damaged or not properly connected"
• NFL 2K1: Tries to connect, then says no modem present.
• Worms World Party: Internet option disabled.
• Samba de Amigo Browser: Got gibberish on serial, like Chu Chu Rocket's browser.
• Jet Grind Radio Browser: No browser option
• Skies of Arcadia Browser: I could access the browser, but it wouldn't connect and there was nothing on the PC.
• Phantasy Star Online v2: Used BBA, website option gave me the BBA configuration screen. With BBA removed, I was allowed to try to connect, but it failed when dialing. Nothing detected on serial. Website option said there was no ISP information.
• Unreal Tournament: Tried to use BBA. With BBA unplugged, and the expansion port empty, it behaved as though there was a modem connected. When dialing, it tried for a bit, then said it failed without the PC detecting anything.
• Quake 3 Arena: Tried to use BBA. With BBA unplugged, and the expansion port empty, it behaved as though there was a modem connected. Required me to enter dial up settings, settings did not seem to save. When trying to dial, it immediately said it failed, and the computer didn't seem to receive anything.
• Propeller Arena (burnt disc): I got something on the serial port, but it was gibberish. It was a different pattern than Chu Chu Rocket's browser. The BBA Setup option was disabled, even though I had a BBA installed. This is the only time I got anything on the serial port that wasn't from a browser.

I think that's everything worth trying that I own. I don't have Alien Front Online, Outtrigger, or Speed Devils Online, and I didn't bother with PlanetWeb 2.0, since it probably works like Sonic Adventure's browser. I also skipped PSOv1, since it's probably similar to v2. I could have tried more game browsers, but I doubt there would be anything different from the ones I tried. I don't have any Japanese or European games with any interesting online functions.

The fact that anything works correctly with it is better than I expected. Someone with an oscilloscope or logic analyzer needs to try this again to verify that there's actually nothing happening were is looks like nothing's happening, and to find out what's going on with the corrupt transmissions. There's also the possibility that my serial adapter started acting up while testing (it's happened before), or I misconfigured the serial port on the PC (like wrong handshaking), or there's an issue with my coder's cable, and one of these resulted in nothing being detected when something really was happening.. But since DreamKey worked so well, it was probably good enough.

At some point, I'll try seeing if I can get DreamKey to connect to a PPP server on my PC over serial, and access the internet through that.

[SEGA RPG FAN]

Have you tried with the standard modem installed on the chance the games get tripped up by having an unsupported peripheral installed?

[TapamN]

No, I haven't tried that. It's worth a shot.

Also, I went back and tried running DreamKey again, but the option to use the browser is missing, with only the option to setup the internet connection. I think while trying out the games, some game that asked me to enter connection settings, like Quake 3, write messed up settings to flash, so that DreamKey doesn't recognize it anymore. This might have prevented some games from working.

Selecting the setup option on the burnt DreamKey causes the system to reset. I guess it tries to switch to a different executable, and it fails running from a CD-R? Luckily, I backed up my flash before I tried all of this, so I can restore my initial settings and get back into DreamKey.

[colgate]

Interesting find, I wonder if there is any relation with the ISDN modem that we know little about:

https://www.thedreamcastjunkyard.co.uk/ ... -7430.html

[TapamN]

I restored my flash and have done some extra experimentation.

With the BBA installed, and using this virtual modem script, I was able to browse the internet across the serial port using DreamKey 3.0. I tried visiting example.com, Marcus Comstedt's site, and DreamPipe. They all worked perfectly.

With the modem installed, I tried Sonic Adventure, Chu Chu Rocket, PSOv2, and Propeller Arena. With SA, I got something on the serial port when loading the browser (which didn't happen before), but nothing when trying to connect. Chu Chu Rocket, PSOv2, and Propeller Arena behaved mostly same as before, but it took longer for them to give up connecting.

Edit: I benchmarked the DreamKey connection by downloading a 950 KB PNG file. It took 93 seconds, which comes out to about 10 KB per second.

[colgate]

That's cool! I wonder if you check the files in the dream key disc, if we can find something related to the serial port, a driver or something like that.

This topic deserves more attention.