Path: utzoo!utgpu!news-server.csri.toronto.edu!bonnie.concordia.ca!uunet!munnari.oz.au!uniwa!andreww
From: andreww@uniwa.uwa.oz (Andrew John Williams)
Newsgroups: sci.electronics
Subject: Re: ECL logic computers ?
Message-ID: <1991Jun27.052307.26836@uniwa.uwa.oz>
Date: 27 Jun 91 05:23:07 GMT
References: <7183@gara.une.oz.au>
Organization: University of Western Australia
Lines: 20

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
>run at.I know it uses more power than CMOS logic,
>...but if it could
>run at the above speed [400-500MHz], wouldn't it be worth the effort.  

As far as I'm aware, the main reason is price. ECL is not cheap. Some
high-end machines do in fact use it, and they benefit from the extra
speed. But you pay for it. ECL chips are low-density (transistor size,
power consumption (too many gates and it melts)). Also, to run at
500MHz, you'd need rather fast RAM. OK, you say - build that with ECL as
well. Unfortunately... a few meg of ECL SRAM would fill a VERY large
box, require some very expensive cooling, and cost an absolute FORTUNE!.
People like their PCs small, cheap to buy and cheap to run. You could
run an ECL CPU with normal DRAM, but you'd lose almost all of the extra
speed.

John West (stealing Andrew's account)
wibblefish