Article View: comp.arch
Article #11647Re: condition codes
From: Dik T. Winter
Date: Fri, 17 May 1991 10:42
Date: Fri, 17 May 1991 10:42
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1714 bytes
In article <15909@darkstar.ucsc.edu> haynes@felix.ucsc.edu (99700000) writes:
> Well if we could go back to the Burroughs B5500 of 1964 vintage we
> wouldn't have. An integer on that machine was simply a floating point
> number with a zero exponent; the hardware algorithms tried to keep the
> exponent zero as long as possible, rather than always normalizing.
The same was true for the (Dutch) Electrologica X8 of the same vintage:
keep the absolute value of the exponent as small as possible without losing
precision.
> I believe the concept
> actually goes back to Householder of Oak Ridge in the 1950s.
I do not think so. Here it was always called the Grau representation of
floating-point numbers (and Householder was well known). It was based on
the following article:
Grau, A.A.
On a Floating-Point Number Representation For Use with Algorithmic
Languages.
Communications of the ACM, 5 (1962), 160-161.
This was for a large part influenced by:
Ashenhurst, R.L., and Metropolis, N.
Unnormalized floating-point arithmetic.
Journal of the ACM, 6 (July 1959), 415-428.
which is the oldest reference I have found that uses 'unnormalized' fp numbers.
--
dik t. winter, cwi, amsterdam, nederland
dik@cwi.nl
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Path: arc1-ca.pugleaf.net!utzoo!utgpu!news-server.csri.toronto.edu!bonnie.concordia.ca!uunet!mcsun!hp4nl!charon!dik From: dik@cwi.nl (Dik T. Winter) Newsgroups: comp.arch Subject: Re: condition codes Message-ID: <3558@charon.cwi.nl> Date: 17 May 91 10:42:23 GMT References: <13011@pt.cs.cmu.edu> <12236@mentor.cc.purdue.edu> <15909@darkstar.ucsc.edu> Sender: news@cwi.nl Organization: CWI, Amsterdam Lines: 25