Re: old floating point, C arithmetic, was Software proofs, was Are there different

gah4 <gah4@u.washington.edu>
Sat, 11 Feb 2023 22:48:41 -0800 (PST)

          From comp.compilers
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[4 earlier articles]
Re: C arithmetic, was Software proofs, was Are there different gah4@u.washington.edu (gah4) (2023-02-06)
Re: C arithmetic, was Software proofs, was Are there different DrDiettrich1@netscape.net (Hans-Peter Diettrich) (2023-02-07)
Re: C arithmetic, was Software proofs, was Are there different anton@mips.complang.tuwien.ac.at (2023-02-08)
Re: C arithmetic, was Software proofs, was Are there different DrDiettrich1@netscape.net (Hans-Peter Diettrich) (2023-02-10)
Re: C arithmetic, was Software proofs, was Are there different gah4@u.washington.edu (gah4) (2023-02-10)
Re: C arithmetic, was Software proofs, was Are there different anton@mips.complang.tuwien.ac.at (2023-02-11)
Re: old floating point, C arithmetic, was Software proofs, was Are there different gah4@u.washington.edu (gah4) (2023-02-11)
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From: gah4 <gah4@u.washington.edu>
Newsgroups: comp.compilers
Date: Sat, 11 Feb 2023 22:48:41 -0800 (PST)
Organization: Compilers Central
References: 23-01-092 23-02-003 23-02-019 23-02-025 23-02-026 23-02-029 23-02-033 23-02-037 23-02-038 23-02-040
Injection-Info: gal.iecc.com; posting-host="news.iecc.com:2001:470:1f07:1126:0:676f:7373:6970"; logging-data="61917"; mail-complaints-to="abuse@iecc.com"
Keywords: arithmetic, history
Posted-Date: 12 Feb 2023 12:21:46 EST
In-Reply-To: 23-02-040

(our moderator wrote)


> [Oh, right, I forgot about Zuse. He invented a lot of stuff that other
> people reinvented later. Squinting at my VAX architecture handbook, the
> formats have the same layout as IEEE but the exponents are excess 128 and
> 1024 rather than 127 and 1023 and there's no infinities or denormals. -John]


I always forget the difference between them.


VAX has the binary point to the left of the hidden one, and IEEE to the right.
So that makes up for the one difference in exponent bias.


But no infinity and NaN means that the actual exponent can be one higher.


I think that is the way it works.


I never had problems reading S/360 format from hex dumps, where
the exponent is in whole hexdecimal digits, and no hidden one.

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