Sat, 11 Feb 2023 22:34:25 GMT

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[5 earlier articles] |

Re: C arithmetic, was Software proofs, was Are there different DrDiettrich1@netscape.net (Hans-Peter Diettrich) (2023-02-08) |

Re: C arithmetic, was Software proofs, was Are there different gah4@u.washington.edu (gah4) (2023-02-09) |

Re: C arithmetic, was Software proofs, was Are there different gah4@u.washington.edu (gah4) (2023-02-09) |

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 gah4@u.washington.edu (gah4) (2023-02-11) |

Re: C arithmetic, was Software proofs, was Are there different anton@mips.complang.tuwien.ac.at (2023-02-11) |

Re: C arithmetic, was Software proofs, was Are there different drb@ihatespam.msu.edu (2023-02-12) |

From: | anton@mips.complang.tuwien.ac.at (Anton Ertl) |

Newsgroups: | comp.compilers |

Date: | Sat, 11 Feb 2023 22:34:25 GMT |

Organization: | Institut fuer Computersprachen, Technische Universitaet Wien |

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 |

Injection-Info: | gal.iecc.com; posting-host="news.iecc.com:2001:470:1f07:1126:0:676f:7373:6970"; logging-data="72081"; mail-complaints-to="abuse@iecc.com" |

Keywords: | arithmetic, history, comment |

Posted-Date: | 11 Feb 2023 20:28:32 EST |

gah4 <gah4@u.washington.edu> writes:

*>[I am not aware of any hidden bit formats before IEEE*

The VAX FP formats have a hidden bit

<https://nssdc.gsfc.nasa.gov/nssdc/formats/VAXFloatingPoint.htm>, and

AFAIK VAX F and G are pretty close to IEEE binary32 and binary64.

According to

<https://home.kpn.nl/jhm.bonten/computers/bitsandbytes/wordsizes/hidbit.htm>

already Zuse used a hidden bit in FP numbers on his machines (1940s

and 1950s).

--

M. Anton Ertl

anton@mips.complang.tuwien.ac.at

http://www.complang.tuwien.ac.at/anton/

[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]

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