Xref: utzoo comp.protocols.appletalk:5010 comp.sys.mac.comm:2114
Path: utzoo!utgpu!watserv1!watmath!att!pacbell.com!ucsd!ucbvax!agate!shelby!neon!pescadero.Stanford.EDU!philip
From: philip@pescadero.Stanford.EDU (Philip Machanick)
Newsgroups: comp.protocols.appletalk,comp.sys.mac.comm
Subject: Re: do I need phone net connectors? <summary>
Message-ID: <1991Jan8.190419.17902@Neon.Stanford.EDU>
Date: 8 Jan 91 19:04:19 GMT
References: <1991Jan7.165900.1538@ccu.umanitoba.ca> <1991Jan8.090043.25113@sics.se>
Sender: news@Neon.Stanford.EDU (USENET News System)
Reply-To: philip@pescadero.stanford.edu
Organization: Computer Science Department, Stanford University
Lines: 41

In article <1991Jan8.090043.25113@sics.se>, boortz@sics.se (Kent Boortz) writes:
|> 
|> > One person said he had successfully used an IW II cable to run Appletalk from
|> > one Mac to another, but the general concensus was "Don't bother trying".
|> > One person from TOPS wrote and said I would void my warranty with TOPS if 
|> > I tried that, and may even damage my Appletalk ports.  So I guess I'll be
|> > ordering a couple phone net connectors!
|> 
|> This is very strange in my opinion. An ImageWriter cable is a standard
|> serial cable for mac and is intended for connection of two RS-422 ports.
|> There should be no difference electrically connecting a mac to mac, mac
|> to modem, mac to LaserWriter or mac to ImageWriter.
|> 
|> AppleTalk is software and I don't think software could feel the difference 
|> how you electrically connect the devices in this case.
|> 
|> The intention of the LocalTalk box is to let you mix output signal from 
|> different ports and is needed if more than two LocalTalk equipment are 
|> connected. There is no magic in these boxes.
|> 
|> The only problem I can think of is WHEN an equipment do some magic. This
|> is from what I have heard the case with the DeskWriter printer. It will
|> test the electrical condition of the serial port to determine if you are
|> using a LocalTalk box or a straight cable and switch between AppleTalk
|> and serial mode from this information (that would mean that you can't
|> use the standard print spooler with an ImageWriter cable I suppose).
|> 
|> Well, I can't promise anything. I don't use this setup myself but I
|> can't think of any reason why a straight ImageWriter cable could
|> damage anything.

Someone from HP told me that the only reason you can't connect a DeskWriter
to a Mac in AppleTalk mode using a serial cable is they explicitly check
as described above. He said there is no reason _not_ to do this in other
cases. It is possible that TOPS hardware is designed differently, but in
the general case, an ImageWriter II cable is quite safe to substitute for
network connectors for a 2-node network. If you made up a longer cable
with T-connectors for a more-than-2-node network, you can expect problems.
-- 
Philip Machanick
philip@pescadero.stanford.edu