> >As long as we're talking about Netatalk--I don't have an ethernet card in
> >my Linux machine, nor do I have an Ethernet-capable Mac. Is there a way to
> >set up Netatalk to use the PC serial port and Phonenet connectors like a
> >Mac network? (Before anyone says RTFM, I read the source for the Netatalk
> >drivers and couldn't figure it out...)
> I've been wondering the same thing. You should at the very least be
> able to string a serial cable between the two machines and run ppp.
> --PC
> --
> $ "If a man has recently married, he must not be sent to war or have any $
> $ other duty laid on him. For one year he is to be free to stay at home and $
> $ bring happiness to the wife he has married." --Deuteronomy 24:5 $
> $ So that's why people get divorced--nobody can afford a decent honeymoon. $
Here's a (hopefully) definitive answer on connecting Macs to PCs using
Apple's LocalTalk technology. First, LocalTalk is the (new) name for
the low-speed version of AppleTalk that can operate over PhoneNet. It
has a (reported) speed of 230.4 kbit/sec. In actuality, many Macs (if
not all) operate at about 229.5 kbit/sec (some LocalTalk trivia fer
ya). The 230.4 kbit/sec speed is a legacy of previous versions of the
technology (known as AppleBus, I think), which were invented in the Lisa
era. The two speeds are compatible, as the receiver uses a digital
phase lock loop (DPLL) to recover the clocking info embedded in the data
stream.
LocalTalk is NOT compatible with PC serial ports, nor will it ever be.
The serial chips used in PCs are of the National Semiconductor 8250
legacy. The 8250 is an async only chip, as are all of its successors
(16450, 16550, 16650, etc...) LocalTalk was developed around the Zilog
8530, which is a multiprotocol chip. For LocalTalk operation, the 8530
is programmed for FM0 (bi-phase space) signaling, and communicates
frames using bit-oriented (a la HDLC) framing. Neither of these
functions are available in 8530 and subsequent chips.
The only practical method I know of to get a PC to talk LocalTalk
directly is to purchase a LocalTalk PC card from Farallon Systems (do
they still sell them?). The card was originally developed and sold by
Apple, but they sold off the entire product to Farallon a long time ago
(i.e. at least 5 years). The card uses a Zilog 8530 chip, plus a Z80
compatible microprocessor to implement LocalTalk with minimal overhead
on the PC.
I have one of the LocalTalk PC cards, and have used it in the past with
Windows 3.1. I just saw a posting that indicated that a future version
of the Linux kernel may include support for the LocalTalk PC card.
Luckily, I hadn't sent the card to the trash heap yet. I'm looking
forward to being able to connect my LaserWriter II directly to Linux via
LocalTalk using this card.
Finally, in case you're interested, PhoneNet is a really simple
technology. If you crack open a PhoneNet module, all you'll find is a
transformer. Apple's original equivalent product contains - yep - a
transformer! I'm at a loss as to the technical difference in
implementations, but I suspect that it's not much more than Apple being
too conservative to risk EMI complaints from emissions from (unshielded)
telephone wiring, whereas Farallon (being at the time, much smaller and
hungrier) didn't find such concerns too daunting.