Groups > comp.arch > #2068

Re: History of byte addressing

From	Andrew Reilly <areilly---@bigpond.net.au>
Newsgroups	comp.arch
Subject	Re: History of byte addressing
Date	2011-06-06 23:55 +0000
Message-ID	<9557n9Fvb0U1@mid.individual.net> (permalink)
References	(1 earlier) <248b8b45-50f6-4cd6-b98a-2b57629b3390@c26g2000vbq.googlegroups.com> <18608bba-ef46-4abb-9eed-d94089feb2ce@d28g2000yqf.googlegroups.com> <42477501-047c-4e2e-9697-a6275ad39af3@s14g2000vbi.googlegroups.com> <4debe460$3@news.broadpark.no> <2011Jun6.190346@mips.complang.tuwien.ac.at>

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On Mon, 06 Jun 2011 17:03:46 +0000, Anton Ertl wrote:

> Motorola was inconsistent in the 68000 (and probably in the 6800), where
> byte 0 was most significant, but bit 0 was least significant.

The Motorola 56000 (1986 or so) numbers the bits in registers and as 
accessed by the various instructions that do so (sensibly IMO) according 
to their mathematical significance.  Address endianness doesn't arise 
because there are no sequential-address load store operations.  (It is a 
word addressed processor.)  I've coded byte-packing of strings on it both 
ways, and vaguely remember little-endian being slightly simpler/more 
efficient.

I've never found the "easier for human assembly language programmers to 
read" argument to be particularly convincing, but then I cut my 
programming teath on a Z80, reading 16-bit values "backwards" in hex 
dumps.  Of course any time a number is *intended* to be read as a number, 
a program makes it appear however you want it.  Not having the 
mathematical bit significance correlation with bit-address extend neatly 
into byte/word addresses (in big-endian machines) has always seemed 
broken to me, from an aesthetic perspective, but I don't recall it ever 
actually getting in the way of anything.

Cheers,

-- 
Andrew

Thread

History of byte addressing John Levine <johnl@iecc.com> - 2011-06-02 19:36 +0000
  Re: History of byte addressing nmm1@cam.ac.uk - 2011-06-02 20:38 +0100
    Re: History of byte addressing Quadibloc <jsavard@ecn.ab.ca> - 2011-06-03 08:05 -0700
  Re: History of byte addressing Alex McDonald <blog@rivadpm.com> - 2011-06-03 05:26 -0700
    Re: History of byte addressing Anne & Lynn Wheeler <lynn@garlic.com> - 2011-06-03 09:48 -0400
  Re: History of byte addressing Quadibloc <jsavard@ecn.ab.ca> - 2011-06-03 07:49 -0700
    Re: History of byte addressing Quadibloc <jsavard@ecn.ab.ca> - 2011-06-03 10:56 -0700
  Re: History of byte addressing "Andy \"Krazy\" Glew" <andy@SPAM.comp-arch.net> - 2011-06-04 10:59 -0700
    Re: History of byte addressing Quadibloc <jsavard@ecn.ab.ca> - 2011-06-04 15:01 -0700
      Re: History of byte addressing nmm1@cam.ac.uk - 2011-06-04 22:53 +0100
        Re: History of byte addressing Quadibloc <jsavard@ecn.ab.ca> - 2011-06-05 10:40 -0700
    Re: History of byte addressing John Levine <johnl@iecc.com> - 2011-06-05 06:10 +0000
      Re: History of byte addressing Robert Myers <rbmyersusa@gmail.com> - 2011-06-05 10:00 -0700
        Re: History of byte addressing Robert Myers <rbmyersusa@gmail.com> - 2011-06-05 10:04 -0700
          Re: History of byte addressing Quadibloc <jsavard@ecn.ab.ca> - 2011-06-05 10:36 -0700
            Re: History of byte addressing "Paul A. Clayton" <paaronclayton@gmail.com> - 2011-06-05 11:00 -0700
              Re: History of byte addressing Morten Reistad <first@last.name> - 2011-06-05 21:42 +0200
                Re: History of byte addressing anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2011-06-06 17:03 +0000
                Re: History of byte addressing Andrew Reilly <areilly---@bigpond.net.au> - 2011-06-06 23:55 +0000
                Re: History of byte addressing Quadibloc <jsavard@ecn.ab.ca> - 2011-06-06 18:26 -0700
                Re: History of byte addressing Andrew Reilly <areilly---@bigpond.net.au> - 2011-06-07 05:08 +0000
                Re: History of byte addressing Quadibloc <jsavard@ecn.ab.ca> - 2011-06-07 03:26 -0700
                Re: History of byte addressing Roberto Waltman <usenet@rwaltman.com> - 2011-07-05 20:00 -0400
                Re: History of byte addressing jsavard@excxn.aNOSPAMb.cdn.invalid (John Savard) - 2011-07-06 00:15 +0000
              Re: History of byte addressing George Neuner <gneuner2@comcast.net> - 2011-06-05 16:18 -0400
              Re: History of byte addressing Quadibloc <jsavard@ecn.ab.ca> - 2011-06-05 22:10 -0700
              Re: History of byte addressing torbenm@diku.dk (Torben Ægidius Mogensen) - 2011-06-07 10:50 +0200
                Re: History of byte addressing "Skybuck Flying" <Windows7IsOK@DreamPC2006.com> - 2011-06-07 16:02 +0200
              Re: History of byte addressing "Skybuck Flying" <Windows7IsOK@DreamPC2006.com> - 2011-06-07 15:51 +0200
            Re: History of byte addressing Louis Krupp <lkrupp@nospam.indra.com.invalid> - 2011-06-05 13:43 -0600
              Re: History of byte addressing Quadibloc <jsavard@ecn.ab.ca> - 2011-06-05 22:12 -0700
                Re: History of byte addressing EricP <ThatWouldBeTelling@thevillage.com> - 2011-06-06 02:04 -0400
                Re: History of byte addressing Stephen Fuld <SFuld@alumni.cmu.edu.invalid> - 2011-06-05 23:49 -0700
                Re: History of byte addressing EricP <ThatWouldBeTelling@thevillage.com> - 2011-06-06 13:34 -0400
                Re: History of byte addressing Stephen Fuld <SFuld@alumni.cmu.edu.invalid> - 2011-06-06 10:49 -0700
                Re: History of byte addressing "Andy \"Krazy\" Glew" <andy@SPAM.comp-arch.net> - 2011-06-06 22:42 -0700
                Re: History of byte addressing Anne & Lynn Wheeler <lynn@garlic.com> - 2011-06-07 07:37 -0400
                Re: History of byte addressing Stephen Fuld <SFuld@alumni.cmu.edu.invalid> - 2011-06-07 08:22 -0700
                Re: History of byte addressing "Andy \"Krazy\" Glew" <andy@SPAM.comp-arch.net> - 2011-06-11 09:56 -0700
                Re: History of byte addressing EricP <ThatWouldBeTelling@thevillage.com> - 2011-06-11 14:59 -0400
                Re: History of byte addressing Louis Krupp <lkrupp@nospam.indra.com.invalid> - 2011-06-11 18:52 -0600
                Re: History of byte addressing "Andy \"Krazy\" Glew" <andy@SPAM.comp-arch.net> - 2011-06-12 12:40 -0700
                Re: History of byte addressing Anne & Lynn Wheeler <lynn@garlic.com> - 2011-06-11 15:05 -0400
                Re: History of byte addressing Louis Krupp <lkrupp@nospam.indra.com.invalid> - 2011-06-06 13:10 -0600
                Re: History of byte addressing George Neuner <gneuner2@comcast.net> - 2011-06-06 16:41 -0400
                Re: History of byte addressing Quadibloc <jsavard@ecn.ab.ca> - 2011-06-06 18:13 -0700
                Re: History of byte addressing Louis Krupp <lkrupp@nospam.indra.com.invalid> - 2011-06-06 23:50 -0600
                Re: History of byte addressing Jim Haynes <jhaynes@alumni.uark.edu> - 2011-06-07 10:01 -0500
                Re: History of byte addressing Louis Krupp <lkrupp@nospam.indra.com.invalid> - 2011-06-07 13:09 -0600
                Re: History of byte addressing Louis Krupp <lkrupp@nospam.indra.com.invalid> - 2011-06-07 14:03 -0600
                Re: History of byte addressing Louis Krupp <lkrupp@nospam.indra.com.invalid> - 2011-06-06 05:16 -0600
        Re: History of byte addressing Quadibloc <jsavard@ecn.ab.ca> - 2011-06-05 10:44 -0700
        Re: History of byte addressing John Levine <johnl@iecc.com> - 2011-06-06 05:00 +0000
          Re: History of byte addressing Quadibloc <jsavard@ecn.ab.ca> - 2011-06-05 22:11 -0700
            Re: History of byte addressing nmm1@cam.ac.uk - 2011-06-06 08:00 +0100
              Re: History of byte addressing Quadibloc <jsavard@ecn.ab.ca> - 2011-06-06 18:16 -0700
            Re: History of byte addressing Michael S <already5chosen@yahoo.com> - 2011-06-06 01:01 -0700
              Re: History of byte addressing nmm1@cam.ac.uk - 2011-06-06 08:30 +0100
                Re: History of byte addressing Terje Mathisen <"terje.mathisen at tmsw.no"> - 2011-06-06 10:34 +0200
                Re: History of byte addressing Michael S <already5chosen@yahoo.com> - 2011-06-06 03:29 -0700
                Re: History of byte addressing Terje Mathisen <"terje.mathisen at tmsw.no"> - 2011-06-06 15:21 +0200
                Re: History of byte addressing Michael S <already5chosen@yahoo.com> - 2011-06-06 03:23 -0700
                Re: History of byte addressing MitchAlsup <MitchAlsup@aol.com> - 2011-06-07 08:01 -0700
                Re: alignment, was History of byte addressing John Levine <johnl@iecc.com> - 2011-06-06 18:33 +0000
                Re: alignment, was History of byte addressing nmm1@cam.ac.uk - 2011-06-06 19:30 +0100
                Re: alignment, was History of byte addressing Anne & Lynn Wheeler <lynn@garlic.com> - 2011-06-06 15:32 -0400
              Re: History of byte addressing Quadibloc <jsavard@ecn.ab.ca> - 2011-06-06 18:11 -0700
          Re: History of byte addressing Robert Myers <rbmyersusa@gmail.com> - 2011-06-06 06:48 -0700
            Re: History of byte addressing jsavard@excxn.aNOSPAMb.cdn.invalid (John Savard) - 2011-07-03 16:13 +0000
        Re: History of byte addressing Quadibloc <jsavard@ecn.ab.ca> - 2011-07-03 09:10 -0700
  Re: History of byte addressing "Skybuck Flying" <Windows7IsOK@DreamPC2006.com> - 2011-06-07 16:23 +0200
    Re: History of byte addressing Stephen Fuld <SFuld@alumni.cmu.edu.invalid> - 2011-06-07 08:26 -0700
  Re: History of byte addressing "Skybuck Flying" <Windows7IsOK@DreamPC2006.com> - 2011-06-07 16:25 +0200
    Re: History of byte addressing "Skybuck Flying" <Windows7IsOK@DreamPC2006.com> - 2011-06-07 16:45 +0200
      Re: History of byte addressing "Skybuck Flying" <Windows7IsOK@DreamPC2006.com> - 2011-06-07 16:48 +0200
      Re: History of byte addressing "Skybuck Flying" <Windows7IsOK@DreamPC2006.com> - 2011-06-07 16:59 +0200
        Re: History of byte addressing "Skybuck Flying" <Windows7IsOK@DreamPC2006.com> - 2011-06-07 17:05 +0200
  Re: History of byte addressing Quadibloc <jsavard@ecn.ab.ca> - 2011-06-18 15:43 -0700
  Re: History of byte addressing Quadibloc <jsavard@ecn.ab.ca> - 2011-07-04 03:14 -0700
    Re: History of byte addressing Quadibloc <jsavard@ecn.ab.ca> - 2011-07-04 03:40 -0700
      Re: History of byte addressing Quadibloc <jsavard@ecn.ab.ca> - 2011-07-04 04:28 -0700
        Re: History of byte addressing nmm1@cam.ac.uk - 2011-07-04 13:38 +0100
          Re: History of byte addressing Quadibloc <jsavard@ecn.ab.ca> - 2011-07-04 06:47 -0700
            Re: History of byte addressing nmm1@cam.ac.uk - 2011-07-04 14:16 +0100
        Re: History of byte addressing Bill Findlay <yaldnif.w@blueyonder.co.uk> - 2011-07-04 15:53 +0100
      Re: History of byte addressing Bill Findlay <yaldnif.w@blueyonder.co.uk> - 2011-07-04 15:36 +0100
        Re: History of byte addressing Quadibloc <jsavard@ecn.ab.ca> - 2011-07-04 07:50 -0700
          Re: History of byte addressing John Levine <johnl@iecc.com> - 2011-07-04 19:46 +0000
            Re: History of byte addressing Quadibloc <jsavard@ecn.ab.ca> - 2011-07-04 15:29 -0700
              Re: History of byte addressing Bill Findlay <yaldnif.w@blueyonder.co.uk> - 2011-07-05 00:02 +0100
      Re: History of byte addressing Bill Findlay <yaldnif.w@blueyonder.co.uk> - 2011-07-04 15:47 +0100
        Re: History of byte addressing Quadibloc <jsavard@ecn.ab.ca> - 2011-07-04 07:54 -0700

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