Path: utzoo!attcan!uunet!husc6!bloom-beacon!mit-eddie!ll-xn!oberon!sdcrdcf!csun!polyslo!dorourke From: dorourke@polyslo.UUCP (David O'Rourke) Newsgroups: comp.protocols.appletalk Subject: Re: PhoneNet cabling Message-ID: <3090@polyslo.UUCP> Date: 5 Jun 88 21:33:22 GMT References:<614@mtxinu.UUCP> <3611@saturn.ucsc.edu> Reply-To: dorourke@polyslo.UUCP (David O'Rourke) Organization: Cal Poly State University -- San Luis Obispo Lines: 23 In article <3611@saturn.ucsc.edu> eshop@saturn.ucsc.edu (Jim Warner) writes: >No. Apple's LocalTalk is RS-422 balanced differential signalling. I was under the impression that differential signalling requires two wires for each signal. So that would require Apple's LocalTalk to use 5 wires, 2 for Transmitt, 2 for Recieve, and 1 for ground. Well LocalTalk only has 3 wires, 1 transmit, 1 Recieve, 1 ground. Besides I was told by an EE person who looked at Apple's Transformer specs in inside AppleTalk that their wiring scheme reaks more of RS-423 (RS-432??). In any after looking at the specs for the LocalTalk box, and the number of wires in the LocalTalk cable, the 20 or so people I've talked to seem to think apple isn't using the RS-422 at all. And after looking at how they wired the 8530 these people were even move convinced that Apple isn't using the RS-422 standard at all, they seem to be using a tweaked version somewhere between RS-232 & RS-422. In any case I might be wrong, but I don't think LocalTalk is run on top of RS-422 as you stated. -- David M. O'Rourke Disclaimer: I don't represent the school. All opinions are mine!