Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!samsung!emory!gatech!prism!gt0869a
From: gt0869a@prism.gatech.EDU (WATERS,CLYDE GORDON)
Newsgroups: sci.electronics
Subject: Re: ECL logic computers ?
Message-ID: <31917@hydra.gatech.EDU>
Date: 27 Jun 91 23:31:29 GMT
References: <7183@gara.une.oz.au> <1991Jun27.052307.26836@uniwa.uwa.oz>
Organization: Georgia Institute of Technology
Lines: 28

In article <1991Jun27.052307.26836@uniwa.uwa.oz> andreww@uniwa.uwa.oz (Andrew John Williams) writes:
>rbennet1@gara.une.oz.au (Robert Bennetts) writes:
>>    can anybody out there tell me why ECL logic is not used to construct
>>computers (to my knowledge anyway) considering the quite fast speeds it can
>As far as I'm aware, the main reason is price. ECL is not cheap. Some
>
>John West (stealing Andrew's account)
>wibblefish

Another reason is that ECL seems to be a little (lot?) more noise-prone 
than standard TTL logic. Since the transistors never saturate, the voltage 
swing is not as great either. This means that the difference between '1'
and '0' is not as great anymore. Flipped bits and other errors caused
by voltage transients on the data lines can cause problems. I believe
that this is one primary reason that ECL is not used very much. The 
equipment would have to be shielded better, also raisong the price.
I have heard of ECL being used on high-speed counters, but not for
much else. Unless the speed is ABSOLUTELY necessary, most designers
go for the more fool-proof arrangements. 
My $.02
REgards,
Gordon.

-- 
WATERS,CLYDE GORDON-Georgia Institute of Technology Atlanta Ga 30332 
******<LANGUAGE IS A VIRUS! - Laurie Anderson-Home of the Brave>******* 
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