Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.PCS 1/10/84; site ahuta.UUCP Path: utzoo!watmath!clyde!burl!ulysses!mhuxr!mhuxj!houxm!ahuta!dmt From: dmt@ahuta.UUCP (d.tutelman) Newsgroups: net.micro,net.college Subject: Re: Overloaded Computing Systems Message-ID: <333@ahuta.UUCP> Date: Tue, 8-Jan-85 08:46:15 EST Article-I.D.: ahuta.333 Posted: Tue Jan 8 08:46:15 1985 Date-Received: Wed, 9-Jan-85 03:26:31 EST References: <773@amdahl.UUCP> <10468@watmath.UUCP> <1312@eosp1.UUCP> <4844@utzoo.UUCP>, <7195@watrose.UUCP> Organization: AT&T Information Systems Labs, Holmdel NJ Lines: 34 Xref: watmath net.micro:9023 net.college:622 REFERENCES: <773@amdahl.UUCP> <10468@watmath.UUCP> <1312@eosp1.UUCP> <4844@utzoo.UUCP>, <7195@watrose.UUCP> > The last time I used an IBM 4341 (approx CPU power of a VAX 780) with > 80 users (active) to do editing on a 3278, there was a minimal degree > of I/O wait involved...... > The point is this.. mainframe channel-style architecture exacts a small > convenience price for a huge performance improvement. > Real life has confirmed this many times over for me, and that's why I'd > rather use VM/CMS for editing than vi and 4.2bsd, especially if system load > is a problem. > ...... > Wether the performance improvement is due to full duplex or not, I cannot > answer, but I can type and read input simultaneously on a 3278, so it looks > all the same to me !!! Once again ..... The performance improvement has little to do with EITHER full-duplex or "Mainframe channel-style carchitecture". It lies in the combination of terminal and application: - The 3278 terminal does not send every character as it is keyed in. In most applications, it doesn't even send lines, but full screens. I'm not sure exactly what you're doing, but I bet you're using the buffering and screen editing built into the 3278 in some useful way. - "vi" uses raw input, which interrupts the application every keystroke.... VERY consumptive of real time. It is NOT the full-duplex transmission (used by UNIX in line input mode as well) that's causing the problem. If your mainframe application needed to capture arbitrary keystrokes, all the channel architecture in the world wouldn't keep it from being a drain on real time. Dave Tutelman