Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!cs.utexas.edu!ginosko!usc!rutgers!cmcl2!adm!smoke!gwyn From: gwyn@smoke.BRL.MIL (Doug Gwyn) Newsgroups: comp.unix.wizards Subject: Re: terminals/term. servers Message-ID: <11225@smoke.BRL.MIL> Date: 5 Oct 89 14:34:03 GMT References: Reply-To: gwyn@brl.arpa (Doug Gwyn) Organization: Ballistic Research Lab (BRL), APG, MD. Lines: 25 In article sr16+@andrew.cmu.edu (Seth Benjamin Rothenberg) writes: >We were told that character input from hardwired terminals (as opposed to >virtual terminals) causes cpu interrupts. Is this true? Would this >slow the machine down a great deal? It depends on the serial line multiplexer and the operating system. Most commonly encountered VAX serial line multiplexers are used by most common UNIX implementations in a single interrupt per character mode. (There are exceptions, generally involving I/O processors.) It's not a large problem for typical installations. >Most of the systems I know of use telnet (or LAT) logins almost exclusively. >Are hardwired terminals just as efficient? The main advantage of Ethernet access is that, until the net gets saturated, you can sustain higher throughput. Most RS-232 terminals cannot communicate faster than 19,200 bps. >BTW, if we go to ethernet, should we leave the existing wiring >in place in case of an "emergency"? I wouldn't think it would help. If your Ethernet stops working, it would be less work to fix it than to convert from an Ethernet base to an RS-232 one.