Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!usc!orion.oac.uci.edu!ucivax!laxsqnt!daveman From: daveman@laxsqnt.UUCP (David Mansfield) Newsgroups: comp.sys.sequent Subject: Re: naive question about tty ports Message-ID: <10530@laxsqnt.UUCP> Date: 16 Jan 91 16:40:58 GMT References: <14@mcglin.wpg.com> Organization: Sequent Computer Systems, Costa Mesa, CA Lines: 43 wqb@ufycorp.Unify.Com (Bill Bonney) writes: >In article <14@mcglin.wpg.com> julia@mcglin.wpg.com (Julia Crawley) writes: >>In the next few weeks, my organization will be getting a Basic 4 >>GPX 6270 (i.e., a Sequent). Our vendor is telling us that proper >>cabling of our in-house terminals will require four pairs? Is this >>true? Or, will three wires for 2,3,&7 be sufficient? >> >>-- >>Julia Crawley -- (504) 586-1200 >>julia@mcglin.wpg.com >>uunet!wpg!mcglin!julia >We have a Sequent and are using 3 pair now (I think we use 2, 3, 5, 7, 8 & >20). We are working with a cabling vendor to reduce to 2 pair (2, 3 and >we're working on which other 2 are necessary). We think there will be some >printers we have (we have some old stuff still running) that will still >require 3 pair, but have never needed 4 pair. DCE needs 2, 3, 7, and 8. DTE needs to run 2, 3, 7, and 20: DCE DTE 2 =====> 3 3 =====> 2 7 =====> 7 8 =====> 20 The Sequent ports use pin 8 (DCD) to determine if a device is attached to the port or not. Since most devices hold pin 20 (DTR) high when turned on, you need to map 20 back into 8. Where this falls short is for devices (as Bill mentions, some printers) using hardware handshaking: Dropping DTR cause the port to become "hung up" and the associated process hangs up. There are some other options for how the port and cable can be configured using "ttyconfig" (I'm not sure the MBF machine has this or not). ==== Dave Mansfield ..!sequent!daveman daveman@sequent Sequent Computer Systems, Inc.