DIY Localtalk - Ethernet converter

[bd1308]

I have a EtherPrint ethernet-to-localtalk bridge that seems to work well enough to netboot my IIGS from and connect to a netatalk share I have locally. I'm not sure what the traditional baud rate of the serial side is -- I assume 230K -- but I'm pretty sure I could emulate this functionality in a couple of arduinos. So I've been taking data snapshots of Appletalk packets coming from various equipment on the localtalk side (from the bridge) and packets from the ethernet side to the bridge. The format seems to be straight-forward. The packet captures were taken with Wireshark. Once I figure out how to convert the Localtalk serial RS-422 to RS-232, then I might be able to listen to communication on the serial side. I'm sure Basilisk II and other OSS emulators will help out in this regard too.

Anybody interested in something like this? The nice part about a solution liek this is that it's totally modular -- there's nothing to say a beaglebone or embedded ARM machine with GPIO pins couldn't handle and supplant this solution with additional things like a netatalk Appleshare system or other things....

 

[Bunsen]

I'm definitely going to be keeping an eye on this thread.

 

[bd1308]

The wirehark logs make the bitstream look a little cryptic, but it certainly follows *a* pattern that I can see. I just need to do more research on what each "message" across the ethernet wire looks like, document those, and then move onto the serial side to see what the serial side looks like. If they match, i'm a winner and this will be probably be really easy.

I'll do some tests this weekend now that appletalk/netatalk/ethertalk communication is again established in the home base.

 

[bd1308]

So as soon as I came home, I grabbed a OS9 machine and a Leopard machine and my Linux laptop to act as hallway monitor.

Fired up Wireshark --- and......a TON of packets from my wife on the LAN, because she's doing homework. And it's too much to sort through. So I brought out a old dd-wrt router, and rinsed/repeated. This time I was able to capture the *entire* conversation between the OS9 TiBook and the Powerbook G4.

Here's the steps I followed:

-Went to chooser, typed in IP*

-Hit OK, got login prompt. Entered correct password, but invalid username (I could say I meant to do this, but I didn't lol)

-Mounted 'Macintosh HD' after successful login.

-Browsed the HD for a bit

-Dragged Appletalk-mounted HD to trash.

COnfirmed server disconnection, then stopped wireshark capture. The protocol itself is pretty straightforward. What i'm hoping is the pieces i'm seeing on the ethernet side (in ASCII) correspond to what I will eventually see on the serial-only side

SO the next step is to build a device that will listen to the serial bus and spit out what its saying.... then match them up.

*fingers crossed*

 

[Trash80toHP_Mini]

Nice Hack!

 

[bd1308]

Thanks -- It's nice knowing I can give back to the vintage mac community. According to some, I might be able to make RS-422 work like RS-232 which would work nicely in my arduino, but I'm not sure its literally that easy. Anybody else have any ideas on that?

Once I get that part worked out, the fun part will be making the glue that is between the ethernet side and the localtalk side.

And another question is -- should I just go ahead and make this more compatible with the common phonenet boxes and just figure out how *they* work while i'm in there (since I dont actually have a serial cable)...or should I just stick with regular ol' localtalk?

Actually thinking about it, I might incorporate Zigbee into the mix too, because whats even better than having a wireless localtalk network is having a bridged and wireless localtalk network --- then you'd just need a "base station" and just a converter on each machine.

 

[Trash80toHP_Mini]

I always thought 232 was a shorter distance subset of 422 and they were pretty much compatible right off the bat.

What kind of serial cable do you need, straight or null-modem (Printer) for DIN8 or D-shell (whatever)-9 pin.

PM me with your needs for a freeb.

Actually post'em here just in case I don't have what you need.

 

[bd1308]

Now I believe they're *compatible* but i'm not sure how compatible. Some say apple supported 232 right out of the port for modems, but I'm not totally sure if I do whatever is needed to make it look like a 232 port if i'd get appletalk traffic, and then other sites say it's a differential interface, and you tie certain pins to ground, like TX- and RX- or something. I'm trying to find the link I found at work.

http://pinouts.ru/Converters/rs422_cable_pinout.shtml

Now we're talking.

 

[bd1308]

I found out that the data is encoded using some modulation to ensure the data is valid and that the Appletalk driver itself (in software) talks directly to the port, not via any other serial method. I was confused to find out that schematics for creating a DIY phonenet box didn't include *anything* with DTR/DCD lines, but that's because the mac is more or less bit-banging the serial port itself rather than relying on the standard spec. I found a book called Inside Appletalk that i'm trying to procure now for more information. If anybody has this book PM me.

http://www.mactech.com/articles/mactech/Vol.02/02.04/ATalkConnections/index.html

 

[ClassicHasClass]

I have Inside AppleTalk (the book). No, you can't have it, but I can try to look stuff up in it for you. I thought I had the Inside Macintosh pdf of it, but it looks like I don't.

 

[bd1308]

Eh -- it's on amazon for like $4. So i'll just buy it. I dont even know at this point which questions to ask so i'll just buy it.

I really really really am on top of this project though lol

 

[Gil]

[No message]

 

[bd1308]

Problem with that is instead of a picture you get some garbage text like FULL PG PIC or something....

And the font for some reason is KILLING my eyes --

 

[Bunsen]

Come on guys. We don't do piracy here, you know that.

 

[bd1308]

Inside Appletalk in hardback form has been purchased. I suppose at some point i'll need to buy/build a logic analyzer but for now more research is needed.

 

[Bunsen]

Any of these any use to you?

http://en.wikipedia.org/wiki/Bus_Pirate

http://en.wikipedia.org/wiki/PLAICE

I may add more as I find them.

/eta/

https://www.sparkfun.com/products/9857 aka http://dangerousprototypes.com/open-logic-sniffer/

 

[bd1308]

The hurdle I'm at now is the physical connection. I'm not sure if I can just wire the port up like RS232 (as on the Mac to internet via serial thread) or If I have to go RS422. I can buy the transceivers online, so thats not a problem, it just isn't fun waiting for parts.

 

[Trash80toHP_Mini]

The serial/printer combo port on the Duos worked just fine with PC oriented Modems, if that tells you anything useful. It seems like you probably covered that already . . . but just in case.

 

[techknight]

RS-422 is a point to point only. just like RS232.

In order to setup a bus network, it has to be converted to RS-485, which is what the phonenet stuff actually does. in sorts...

But you can listen on a direct RS-422 bus if you take the TX/rX lines and mix them. Again, sorta like phonenet does.