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Re: Setting architectural features in stone

Newsgroups comp.arch
Date 2016-08-03 09:50 -0700
References <nnb615$1h2k$1@gioia.aioe.org> <nnn452$548$1@dont-email.me> <nnrcnr$267$1@gioia.aioe.org> <66682c36-81e9-481a-a4d2-1f61e9754ada@googlegroups.com> <nnse5k$m20$1@dont-email.me>
Message-ID <b95e8a65-3429-467b-adcc-e37d9742ad71@googlegroups.com> (permalink)
Subject Re: Setting architectural features in stone
From Quadibloc <jsavard@ecn.ab.ca>

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On Wednesday, August 3, 2016 at 3:40:06 AM UTC-6, Nick Maclaren wrote:

> Nuts.  Sorry, but ....  Such machines were common, and they almost
> all had 48 bit floats and 96 bit double precision.  The latter was
> implemented in various ways, not all with 96-bit accuracy.

It's true that the ICL 1900 had 48-bit floats and 96-bit double precision, and 
likely the Control Data 1604A and its successors did too.

The Foxboro FOX-1 is another compliant example; its double precision was 48 
bits long, but its single precision was only 24 bits long.

I don't call that "almost all", though. Actually, machines with 24-bit words were rather rare. But several did not follow this FORTRAN rule.

Datacraft DC6024, Harris Series 500
48-bit single precision (16 bits unused), 48-bit double precision

3C DDP-24, DDP-124, DDP-224
48-bit single precision (15 bits unused), 48-bit double precision

SEL 840
48-bit single precision, 72-bit double precision

Four-Phase Systems IV/70
48-bit single precision, 72-bit double precision

Other examples of machines that broke the FORTRAN standard:

18-bit word
Univac 418 - 36 bit single precision, 54 bit double precision (3 bits unused).

PDP-4/7/9/15 - 36 bit single precision, 54 bit double precision

16-bit word
IBM 1130 - 32 bit single precision, 48 bit double precision (8 bits unused).

Hewlett-Packard 211x - 32 bit single precision, 48 bit double precision

MIL-STD-1750 - 32 bit single precision, 48 bit double precision.

John Savard

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Re: Setting architectural features in stone Noob <root@127.0.0.1> - 2016-08-01 11:18 +0200
  Re: Setting architectural features in stone Ivan Godard <ivan@millcomputing.com> - 2016-08-01 09:26 -0700
  Re: Setting architectural features in stone anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-08-01 15:48 +0000
  Re: Setting architectural features in stone Quadibloc <jsavard@ecn.ab.ca> - 2016-08-01 10:13 -0700
  Re: Setting architectural features in stone Walter Banks <walter@bytecraft.com> - 2016-08-02 20:09 -0400
    Re: Setting architectural features in stone Quadibloc <jsavard@ecn.ab.ca> - 2016-08-02 18:39 -0700
      Re: Setting architectural features in stone Quadibloc <jsavard@ecn.ab.ca> - 2016-08-03 00:52 -0700
        Re: Setting architectural features in stone Walter Banks <walter@bytecraft.com> - 2016-08-03 06:45 -0400
      Re: Setting architectural features in stone David Brown <david.brown@hesbynett.no> - 2016-08-03 15:02 +0200
    Re: Setting architectural features in stone Quadibloc <jsavard@ecn.ab.ca> - 2016-08-02 19:37 -0700
      Re: Setting architectural features in stone Noob <root@127.0.0.1> - 2016-08-03 10:52 +0200
        Re: Setting architectural features in stone Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-08-03 11:09 +0100
        Re: Setting architectural features in stone Keith Thompson <kst-u@mib.org> - 2016-08-03 08:51 -0700
        Re: Setting architectural features in stone Quadibloc <jsavard@ecn.ab.ca> - 2016-08-03 09:36 -0700
          Re: Setting architectural features in stone George Neuner <gneuner2@comcast.net> - 2016-08-03 20:30 -0400
          Re: Setting architectural features in stone Noob <root@127.0.0.1> - 2016-08-04 13:06 +0200
            Re: Setting architectural features in stone Bruce Hoult <bruce.hoult@gmail.com> - 2016-08-04 06:39 -0700
              Re: Setting architectural features in stone nmm@wheeler.UUCP (Nick Maclaren) - 2016-08-04 17:40 +0000
      Re: Setting architectural features in stone nmm@wheeler.UUCP (Nick Maclaren) - 2016-08-03 09:40 +0000
        Re: Setting architectural features in stone Quadibloc <jsavard@ecn.ab.ca> - 2016-08-03 09:50 -0700
          Re: Setting architectural features in stone Quadibloc <jsavard@ecn.ab.ca> - 2016-08-03 10:14 -0700
            Re: Setting architectural features in stone Quadibloc <jsavard@ecn.ab.ca> - 2016-08-04 06:11 -0700
              Re: Setting architectural features in stone Quadibloc <jsavard@ecn.ab.ca> - 2016-08-04 06:14 -0700
      Re: Setting architectural features in stone Walter Banks <walter@bytecraft.com> - 2016-08-03 07:03 -0400
        Re: Setting architectural features in stone already5chosen@yahoo.com - 2016-08-03 04:12 -0700
          Re: Setting architectural features in stone already5chosen@yahoo.com - 2016-08-03 04:26 -0700
            Re: Setting architectural features in stone Walter Banks <walter@bytecraft.com> - 2016-08-03 07:50 -0400
          Re: Setting architectural features in stone Walter Banks <walter@bytecraft.com> - 2016-08-03 07:35 -0400
    Re: Setting architectural features in stone anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-08-03 06:42 +0000
      Re: Setting architectural features in stone Quadibloc <jsavard@ecn.ab.ca> - 2016-08-03 00:03 -0700
        Re: Setting architectural features in stone anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-08-03 08:30 +0000
      Re: Setting architectural features in stone Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-08-03 11:02 +0100
        Re: Setting architectural features in stone Ivan Godard <ivan@millcomputing.com> - 2016-08-03 03:15 -0700
        Re: Setting architectural features in stone anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-08-03 11:53 +0000
          Re: Setting architectural features in stone Quadibloc <jsavard@ecn.ab.ca> - 2016-08-03 18:03 -0700
            Re: Setting architectural features in stone Bruce Hoult <bruce.hoult@gmail.com> - 2016-08-04 01:54 -0700
            Re: Setting architectural features in stone anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-08-04 09:28 +0000
      Re: Setting architectural features in stone timcaffrey@aol.com - 2016-08-04 09:48 -0700
        Re: Setting architectural features in stone Stephen Fuld <SFuld@alumni.cmu.edu.invalid> - 2016-08-04 10:04 -0700

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