Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.1 6/24/83; site redwood.UUCP Path: utzoo!linus!decvax!decwrl!amd!fortune!foros1!redwood!rpw3 From: rpw3@redwood.UUCP (Rob Warnock) Newsgroups: net.news,net.dcom Subject: Re: 2400 baud modems and uucp inefficiencies Message-ID: <54@redwood.UUCP> Date: Tue, 2-Oct-84 18:25:40 EDT Article-I.D.: redwood.54 Posted: Tue Oct 2 18:25:40 1984 Date-Received: Wed, 3-Oct-84 07:14:17 EDT References: <184@oliveb.UUCP> Organization: Rob Warnock, Redwood City, CA Lines: 31 Jerry Aguirre makes a good point of how, by making uucp be full-duplex (files moving in both directions at once), we could double the traffic between backbone sites. But he uses this point to suggest we not rush out to buy 2400-baud modems. Sorry, that's a non-sequitor. If full-duplex makes it better, then full-duplex at 2400 baud makes it even BETTER! However, another possibility one might consider is to note (as Jerry did) that uucp is essentially half-duplex, make it REALLY be so, and start using the dial-up 9600-baud half-duplex modems that are now available for about 1.5-2 times the 2400-baud prices. Do the arithmetic yourself. (There are buffering/acknowledgement strategies that can make the modem turn-around delay cause a negligible loss of throughput. Hint: batching becomes even more important.) Note: Some implementations of UNIX have difficulty receiving input at 9600 baud, but other have shown that that can be fixed by careful design of the tty drivers and careful attention to interrupt-off times and latencies. (Unfortunately, it is often other non-tty drivers, such as disks, which have long hunks of interrupt-off code in them. It sometimes requires a logic analyzer to find the actual offenders when you are losing input interrupts.) Rob Warnock UUCP: {ihnp4,ucbvax!amd}!fortune!redwood!rpw3 DDD: (415)369-7437 Envoy: rob.warnock/kingfisher USPS: Suite 203, 4012 Farm Hill Blvd, Redwood City, CA 94061