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Path: utzoo!utcs!bnr-vpa!pdbain
From: pdbain@bnr-vpa.UUCP
Newsgroups: net.jokes,net.micro
Subject: Cray-1 shutdown sequence
Message-ID: <87@bnr-vpa.UUCP>
Date: Mon, 14-Jul-86 07:55:28 EDT
Article-I.D.: bnr-vpa.87
Posted: Mon Jul 14 07:55:28 1986
Date-Received: Mon, 14-Jul-86 19:23:51 EDT
References: <452@water.UUCP>
Reply-To: pdbain@bnr-vpa.UUCP (Peter Bain)
Organization: Bell-Northern Research, Ottawa, Ontario
Lines: 9
Xref: utcs net.jokes:19495 net.micro:14705
Summary: 

We all know that you need three or four HLT instructions to
stop a Cray (the first one usually works, the rest are in case it
skids), but few people know that you also have to put a bunch of NOPs
before the HLT. This clears the pipelines prevents damage due to to
the inertia of the data. Think about it - you have a bunch of 64
bit floating point numbers truckin' along at up to 100 MFLOPS,
and you try to stop them suddenly - you are bound to wreck something.

	-peter "Those whom the Gods would destroy, they teach BASIC" bain