Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!swrinde!zaphod.mps.ohio-state.edu!usc!apple!agate!telecom-request From: goldstein@delni.enet.dec.com (Fred R. Goldstein) Newsgroups: comp.dcom.telecom Subject: Re: Questions About New Service Being Installed Message-ID: Date: 26 Mar 91 21:59:56 GMT Sender: Telecom@eecs.nwu.edu Organization: Digital Equipment Corp., Littleton MA USA Lines: 33 Approved: Telecom@eecs.nwu.edu X-Submissions-To: telecom@eecs.nwu.edu X-Administrivia-To: telecom-request@eecs.nwu.edu X-Telecom-Digest: Volume 11, Issue 243, Message 8 of 14 In article , rees@pisa.citi.umich.edu (Jim Rees) writes... > The 1ESS has relays in it, not to do the actual switching, > but to switch ringing voltage and the like on to the loop. It makes a > lot of noise, although nothing like a panel office! The 1ESS (and the 1A, which uses a less antiquated processor) uses reed relays to do the actual switching. They're vacuum-sealed, so they're quieter than the old ones. I suspect that the 1 can do Caller ID too, though Im not sure. > What I'd like to know is what are 2 and 3ESS? What's the difference > between a 1 and a 1A (is it just the processor? Does 1A run Unix?) > And what kind of hardware does a 4ESS have (I've never seen one)? The 2BESS is a "suburban" office, built in the '70s to early '80s, using (I think) reed relays like a 1A. It is basically a scaled down version of the 1A, with a different processor. The 3ESS is a very small analog office, of which very few were built (ca. 1980). The 1 uses an antique CPU with ferrite sheet EPROMs and mag cores. The 1A goes to semiconductor memory. As someone else noted, the 4ESS is a different beast, a big digital toll switch. Fred R. Goldstein Digital Equipment Corp., Littleton MA goldstein@delni.enet.dec.com voice: +1 508 486 7388 Do you think anyone else on the planet would share my opinions, let alone a multi-billion dollar corporation?