AppleTalk over Serial?

About SheepShaver, a PPC Mac emulator for Windows, MacOS X, and Linux that can run System 7.5.3 to MacOS 9.0.4.

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jds10011
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AppleTalk over Serial?

Post by jds10011 »

Hi all--
I've been using SheepShaver for a few things over the last couple of years. Current setup is the 10-25 build running OS 9.0.4 on a MacBook Pro under 10.6.2.

I'm successfully using the KeySpan USB 28 serial device with SheepShaver, at least using ZTerm to send/receive serial commands to actual serial devices. What I'm wondering about is old devices that use AppleTalk networking over the serial port (meant to be used with pre-ethernet macs, but still supported on machines with a serial port that natively run OS 9). A good example is the ancient phone-net dongle, or simply connecting two older macs together with a serial cable for (slow) file transfer.

AppleTalk does not seem to work over this emulated serial port in SheepShaver. I was heartened to see the recent thread about theoretically getting AppleTalk to work over ethernet in SheepShaver, if one is willing to sacrifice networking on the host os while using it, but I'm wondering why the serial port wouldn't work if serial commands can be successfully sent/received. (Guessing this has something to do with the protocol involved not actually being serial, and therefore not correctly handled by the host os or even SheepShaver itself, but I don't know much about these things.)

Any thoughts?
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Cat_7
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Post by Cat_7 »

Hi,

Welcome!
I've read your post, but I wouldn't know how to get Appletalk running over a serial connection. And I don't have the equipment to try. Maybe some else can shed some light on this.
What do you need to do to get SheepShaver to use the keyspan adapter? Or is the serial port just transparently visible in SheepShaver? I assume you did select the serial port for appletalk to run over?
Have you tried this in Basilisk? Or with pre-open transport networking?

Best,
Cat_7
joevt
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Post by joevt »

AppleTalk/LocalTalk is not supported on Keyspan devices even on old Macs that can run Mac OS 9 natively so it won't work in SheepShaver either.

LocalTalk does weird things to the Serial Communications Controller (SCC) on old Macs to select special modes that differ from the standard asynchronous serial communication that the Keyspan supports.
http://en.wikipedia.org/wiki/LocalTalk
http://www.mactech.com/articles/mactech ... index.html

Old Macs used the Zilog Z8530. Here's a link to the datasheet and technical manual of an AMD version of the chip (AM85C30) which shows all the features:
http://www.datasheetcatalog.com/datashe ... 5C30.shtml

The Keyspan drivers probably only expose the baud rate, data bits, stop bits, parity, flow control, and external clock (for MIDI devices) features of their SCC.
realitystorm
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Re: AppleTalk over Serial?

Post by realitystorm »

Posting here because this is one of the top search results. You can do AppleTalk over serial.
https://www.savagetaylor.com/2020/12/15 ... dem-cable/

I used apple remote access on basilisk ii to create the connection. Tested on Windows 10
joevt
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Re: AppleTalk over Serial?

Post by joevt »

realitystorm wrote: Thu Dec 24, 2020 2:18 am Posting here because this is one of the top search results. You can do AppleTalk over serial.
https://www.savagetaylor.com/2020/12/15 ... dem-cable/

I used apple remote access on basilisk ii to create the connection. Tested on Windows 10
The trick here is that you're using Apple Remote Access to pipe AppleTalk over normal regular asynchronous NRZ serial (up to 19.2, 38.4, 57.6, 115.2 Kbps, 8N1) instead of the FM0 230.4 Kbps of LocalTalk.

Regarding the Keyspan USA-28 mentioned in the original post, I can use that and the Keyspan USA-28X in macOS versions from 10.7 Lion (didn't test 10.6 SnowLeopard) to 11.1 Big Sur using the kext from https://www.tripplite.com/support/USA28XG
"Driver for USA-28XG (Mac OS X 10.6.x to 10.8.x)" -> "Mac OS X 10.6.x to 10.8.x_v2.6.4.pkg" -> "KeyspanUSAdriver.kext"
Install the kext manually. Ignore Keyspan Serial Assistant.app.
realitystorm
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Re: AppleTalk over Serial?

Post by realitystorm »

Hoping to push the speed higher, I have the Apple Modem tool for creating CLL files and want to see if I can create one that will work the full 921.6kbit/s (115.2KB/s) my USB/Serial supports.
Users would be people with a IIfx, Quadra 900, and Quadra 950 users, or see if I can figure out how external clocks work. That said, with things like RaSCSI the use for this is a lot less.
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adespoton
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Re: AppleTalk over Serial?

Post by adespoton »

Thanks for linking this here; this is exactly how I connected my iMac to my Colour Classic back in the 90s, but I totally forgot about the OpenTransport Null Modem scripts part. Nice to have it well documented. We may want to approach Dave & Steve about replicating some of that in targeted how-tos on here. For people without a LocalTalk bridge, this is an excellent method of bridging a LocalTalk and an Ethernet network; especially if it's also linked to one of the two Raspberry Pi gateway solutions. With this approach, instead of having to source a rare bridge, people just need a Mini DIN-8 to USB null modem cable (or, as used here, a Mini DIN-8 to RS-232 null modem cable and a USB to RS-232 serial adapter).

Seems to me this should also be even easier for Macs with a GeoPort modem port, as you just need the OT null script attached to this, and plug in an RJ-11 (telephone) cable with TX and RX reversed on one end, and splice the other end into an RS-232 plug (or buy a TelePort or similar adapter), and then use a serial to USB adapter.

What I did back in the day was use my iMac's built-in modem on one end and an external modem on the other end, and just disable the modems so it was a null connection whenever the two were on hook. ARA (and ZTerm) then connected cleanly over this link.

Of course, what would be even better is a method to bi-directionally link a modern network topography with a LocalTalk network, so that all devices can access each other via a proxy. I don't think we're quite there yet though; having all devices able to communicate with a central device, either a BII instance or MacIPGW or the BanannaPi AppleTalk Gateway seems to be the current limit.
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