Path: csiph.com!weretis.net!feeder6.news.weretis.net!news.misty.com!news.iecc.com!.POSTED.news.iecc.com!nerds-end From: gah4 Newsgroups: comp.compilers Subject: Re: old floating point, C arithmetic, was Software proofs, was Are there different Date: Sat, 11 Feb 2023 22:48:41 -0800 (PST) Organization: Compilers Central Sender: johnl@iecc.com Approved: comp.compilers@iecc.com Message-ID: <23-02-042@comp.compilers> References: <23-01-092@comp.compilers> <23-02-003@comp.compilers> <23-02-019@comp.compilers> <23-02-025@comp.compilers> <23-02-026@comp.compilers> <23-02-029@comp.compilers> <23-02-033@comp.compilers> <23-02-037@comp.compilers> <23-02-038@comp.compilers> <23-02-040@comp.compilers> MIME-Version: 1.0 Content-Type: text/plain; charset="UTF-8" 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 X-submission-address: compilers@iecc.com X-moderator-address: compilers-request@iecc.com X-FAQ-and-archives: http://compilers.iecc.com In-Reply-To: <23-02-040@comp.compilers> Xref: csiph.com comp.compilers:3383 (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.