Saturn Japanese Xband games are back!

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Mechanic
Toy Commander
Posts: 564

Re: Saturn Japanese Xband games are back!

Post#11 » Sat Jul 04, 2020 8:46 am

Anonymouse wrote:
Mechanic wrote:There was a guy who joined our discord chat last night during fragnight who said he was the creater of xlink or xband i forgot. We told him to join dctalk. Sounded legit


That would be very promising if genuine.
Sent the guy the link to this topic.
Last edited by Mechanic on Sat Jul 04, 2020 8:49 am, edited 1 time in total.
Italian Stallion

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Anonymouse
Beats of Rage
Posts: 417

Re: Saturn Japanese Xband games are back!

Post#12 » Sat Jul 04, 2020 8:48 am

SEGA RPG FAN wrote:
colgate wrote:Wow I'd love to read about how you patched the xband games, have you written something about that?

Sent from my Moto G Play using Tapatalk


Some background:
The Netlink games and the Japanese Xband games are very similar in that they both use a version of the Xband OS. However, they're not similar enough that simply patching in the Netlink software would work. That's the first thing I tried with no luck. The Netlink games are designed to direct dial an opponent and you have complete control over the number dialed. The Japanese games first contact a matching server that passes along opponent info and their phone number then the systems direct dial each other. It's the matching server that hasn't been recreated and has been the reason these games remained locked out to us. I noticed that a certain developer disc contents were dumped online so I started looking at the Netlink documentation. This was useful for describing which xband files/programs were doing what. Most importantly though, the disc included a version of the xband OS that was intended for developers. It was described as essentially a translated version of the Japanese OS with direct-dial functionality bypassing the matching server. It turns out that this version of the OS can replace the Japanese retail OS.

Four main things were changed to the Japanese games:
1. The Xband loader program was replaced with the developer version - this bypasses the modem check and allows both Netlink and Xband modems to work.

2. The Xband OS and libraries were replaced with the developer versions

3. I wanted these games to be forward compatible with a Dreampi solution. This was a challenge because although you can call into the dreampi easily, the dreampi can't ring the phone line on the answer side of the connection. I made it so the answer side attempts to dial out first and connect to the dreampi while keeping that process invisible to the software. If using VoIP, the modem will go into normal wait for ring mode after ~5 seconds. Work is being done on a Dreampi solution, but VoIP still works in the interim.

4. In our testing, we found that 14.4K modem speed (what the JP modem uses) works better with VoIP. It uses a different modulation than the Netlink's 28.8K that seems to survive the VoIP audio encoding better. The games were modified to cap speed to 14.4K so that Netlink users can have the same experience as JP modem users.

Hope that's what you were looking for!


Thank you for the insight, great work!

Do you foresee any performance improvements if you manage to get it working with DreamPi?
Dreamcast: Blue Swirl, 60hz, White LED, Removable battery holder, Internal SD card reader, BBA, DreamPi, RGB Scart

colgate
minority
Posts: 69

Re: Saturn Japanese Xband games are back!

Post#13 » Sat Jul 04, 2020 10:21 am

SEGA RPG FAN wrote:
colgate wrote:Wow I'd love to read about how you patched the xband games, have you written something about that?

Sent from my Moto G Play using Tapatalk


Some background:
The Netlink games and the Japanese Xband games are very similar in that they both use a version of the Xband OS. However, they're not similar enough that simply patching in the Netlink software would work. That's the first thing I tried with no luck. The Netlink games are designed to direct dial an opponent and you have complete control over the number dialed. The Japanese games first contact a matching server that passes along opponent info and their phone number then the systems direct dial each other. It's the matching server that hasn't been recreated and has been the reason these games remained locked out to us. I noticed that a certain developer disc contents were dumped online so I started looking at the Netlink documentation. This was useful for describing which xband files/programs were doing what. Most importantly though, the disc included a version of the xband OS that was intended for developers. It was described as essentially a translated version of the Japanese OS with direct-dial functionality bypassing the matching server. It turns out that this version of the OS can replace the Japanese retail OS.

Four main things were changed to the Japanese games:
1. The Xband loader program was replaced with the developer version - this bypasses the modem check and allows both Netlink and Xband modems to work.

2. The Xband OS and libraries were replaced with the developer versions

3. I wanted these games to be forward compatible with a Dreampi solution. This was a challenge because although you can call into the dreampi easily, the dreampi can't ring the phone line on the answer side of the connection. I made it so the answer side attempts to dial out first and connect to the dreampi while keeping that process invisible to the software. If using VoIP, the modem will go into normal wait for ring mode after ~5 seconds. Work is being done on a Dreampi solution, but VoIP still works in the interim.

4. In our testing, we found that 14.4K modem speed (what the JP modem uses) works better with VoIP. It uses a different modulation than the Netlink's 28.8K that seems to survive the VoIP audio encoding better. The games were modified to cap speed to 14.4K so that Netlink users can have the same experience as JP modem users.

Hope that's what you were looking for!
Yep this is amazing, thank you for sharing. Truly amazing how using the developers OS saved the day, we can probably imagine that the netlink version is basically the xband os without the matching server, right?

At some point I had both modems in my collection, xband and netlink, I would never image I would see they working again, even together!

Sent from my Moto G Play using Tapatalk

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SEGA RPG FAN
GD-ROM
Posts: 460

Re: Saturn Japanese Xband games are back!

Post#14 » Sat Jul 04, 2020 10:41 am

Anonymouse wrote:
Thank you for the insight, great work!

Do you foresee any performance improvements if you manage to get it working with DreamPi?


We're working with someone who has experience with the xband protocols. That part of the equation is beyond me. The hope is that with a custom software we'll be able to have more control over how the games sync with each other and increase performance. An interesting discovery is that in a case where a Netlink and Xband version of a game exists, like Bomberman for example, the Netlink version plays better.
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Xiden
Resident Evil
Posts: 1767

Re: Saturn Japanese Xband games are back!

Post#15 » Sat Jul 04, 2020 6:57 pm

SEGA RPG FAN wrote:
Anonymouse wrote:
Thank you for the insight, great work!

Do you foresee any performance improvements if you manage to get it working with DreamPi?


We're working with someone who has experience with the xband protocols. That part of the equation is beyond me. The hope is that with a custom software we'll be able to have more control over how the games sync with each other and increase performance. An interesting discovery is that in a case where a Netlink and Xband version of a game exists, like Bomberman for example, the Netlink version plays better.


Makes me wonder if there was a later version of the xband dev software out there

colgate
minority
Posts: 69

Re: Saturn Japanese Xband games are back!

Post#16 » Sat Jul 04, 2020 10:28 pm

Are the modems the same hardware? Besides different speeds.

Sent from my Moto G Play using Tapatalk

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SEGA RPG FAN
GD-ROM
Posts: 460

Re: Saturn Japanese Xband games are back!

Post#17 » Sat Jul 04, 2020 11:14 pm

colgate wrote:Are the modems the same hardware? Besides different speeds.

Sent from my Moto G Play using Tapatalk

They're different hardware, but modems are pretty standardized so they both accept the same commands, give the same responses etc.
PSO Dreamcast 100% Legit: Eda FOmarl, Automaton HUcast

colgate
minority
Posts: 69

Re: Saturn Japanese Xband games are back!

Post#18 » Sat Jul 04, 2020 11:17 pm

SEGA RPG FAN wrote:
colgate wrote:Are the modems the same hardware? Besides different speeds.

Sent from my Moto G Play using Tapatalk

They're different hardware, but modems are pretty standardized so they both accept the same commands, give the same responses etc.
Yeap but the OS needs a driver to talk to it, it's funny how the JP games supports US modems and vice versa, maybe they have the same Chipset.. Really cool stuff.

Sent from my Moto G Play using Tapatalk

JamesOfMercia
noob
Posts: 1

Re: Saturn Japanese Xband games are back!

Post#19 » Mon Jul 13, 2020 5:51 am

Thanks for all your hard work converting this software to work with either of the Saturn modems and over VoIP.

I have a question that I don't think I've seen answered.

Will these games now work over a telephone line emulator/simulator, specifically if one Saturn uses a Japanese modem and one uses the US modem?

Before these patches existed I was told the Japanese modem was essentially useless for any local setup which is something I'm hoping to make for myself.

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mistamontiel
Outrun
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Re: Saturn Japanese Xband games are back!

Post#20 » Mon Jul 13, 2020 8:16 am

I second that! Great question

Welcome!

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