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From: henry@utzoo.UUCP (Henry Spencer)
Newsgroups: comp.society.futures
Subject: Re: How Warm Superconductors Change Things
Message-ID: <8964@utzoo.UUCP>
Date: Fri, 20-Nov-87 13:02:13 EST
Article-I.D.: utzoo.8964
Posted: Fri Nov 20 13:02:13 1987
Date-Received: Fri, 20-Nov-87 13:02:13 EST
References: <2824@batcomputer.tn.cornell.edu> <1062@phoenix.Princeton.EDU>, <2208@sputnik.COM>
Organization: U of Toronto Zoology
Lines: 17

> ... A fully superconducting chip is limited in capactiy only
>     by the density with which components can be laid out.  There will be no
>     problem with the thing getting hot and melting down...

Sorry, not true.  For one thing, superconductors have zero resistance only
for DC, not for signals that change.  For another thing, switching devices
generally dissipate heat when they switch.  Cooling was one of the bigger
problems with Josephson Junction technology in the liquid-helium days,
not in the sense of getting stuff down to those temperatures but in the
sense of keeping it there when it was generating substantial amounts of
heat.

Superconductors certainly *help*, potentially a lot, but they aren't a
magic way around the heat problem.
-- 
Those who do not understand Unix are |  Henry Spencer @ U of Toronto Zoology
condemned to reinvent it, poorly.    | {allegra,ihnp4,decvax,utai}!utzoo!henry