Article View: comp.arch
Article #3065Re: What CMOS cannot do (Re: Surges)
From: Brian L. Stuart
Date: Mon, 20 Nov 1989 02:09
Date: Mon, 20 Nov 1989 02:09
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In article <1906@eric.mpr.ca> hui@mprgate.mpr.ca writes: > >Isn't it true that 50 ohm transmission line drivers and receivers can be >reliably and economically made in CMOS? >Once you have a controlled impedence transmission line on your PC >board, _any_ data rate is possible provided the internal data rates of >your chips are fast enough, and your line drivers and receivers are up >to it. While transmission rates can be increased by using matched drivers and receivers, you also need to have the characteristic impedance of the intervening transmission line also matched. Things can get really weird if you have some fan-out (i.e. one driver and several receivers in parallel). Another drawback is that such drivers draw more current. In general, the idea is altogether feasable, but related factors are one of the reasons that design of machines like Cray's is difficult. Brian L. Stuart Department of Computer Science Purdue University
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Path: arc1-ca.pugleaf.net!utzoo!utgpu!attcan!uunet!dino!sharkey!mailrus!purdue!bls From: bls@cs.purdue.EDU (Brian L. Stuart) Newsgroups: comp.arch Subject: Re: What CMOS cannot do (Re: Surges) Summary: Transmission lines are difficult Message-ID: <8681@medusa.cs.purdue.edu> Date: 20 Nov 89 02:09:40 GMT References: <7000@pt.cs.cmu.edu> <31547@hal.mips.COM> <48393@bbn.COM> <7032@pt.cs.cmu.edu> <1906@eric.mpr.ca> Reply-To: bls@cs.purdue.edu (Brian L. Stuart) Organization: Department of Computer Science, Purdue University Lines: 22