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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>
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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