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From: cdshaw@watrose.UUCP (Chris Shaw)
Newsgroups: net.rumor,net.arch
Subject: Re: Josephson & IBM
Message-ID: <7348@watrose.UUCP>
Date: Sat, 16-Mar-85 23:15:09 EST
Article-I.D.: watrose.7348
Posted: Sat Mar 16 23:15:09 1985
Date-Received: Sun, 17-Mar-85 02:18:48 EST
References: <862@ames.UUCP> <340@mhuxm.UUCP> <1729@hplabs.UUCP> <9255@brl-tgr.ARPA>
Reply-To: cdshaw@watrose.UUCP (Chris Shaw)
Organization: U of Waterloo, Ontario
Lines: 28
Xref: watmath net.rumor:690 net.arch:991
Summary: IBM gave up, but the Japanese are still at it !

................................
> > >  Of course, the ballistic gate speeds (100 femtosecond range) ...
> >
> > about 10 picoseconds delay per gate ...
> 
> Nope.  Try Josephson junctions.  Gate delays less than 10ps ...

"About 10ps" is compatible with that and both are far from 100fs.

IBM was working on Josephson junctions when I was a youngster.
What is the holdup?
...................................

According to Feb 25, 1985 ElectronicsWeek, research continues on Josephson
technology. The "holdup" is that IBM gave up its rather large research effort
about 18 months ago. The goal of the research was to have a mainframe computer
by late 1986. The problem was (among other things) getting the
circuits cold enough to superconduct, and/or finding materials that don't
require temperatures as low as 4 Kelvins.
  The Japanese still hope to have something not too far off. Their efforts
are proving fruitful... NTT (Japan's AT&T) has reported  "..a 1-K lead-based
Josephson memory chip that exhibits a 3.3nS access time, with gate delays
of 4.2 pS..."

   IBM is still working on other high-speed projects, however...
read the article for full details.

Chris Shaw