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Re: What is an N-bit machine?

From Lynn Wheeler <lynn@garlic.com>
Newsgroups comp.arch
Subject Re: What is an N-bit machine?
Date 2024-11-29 17:42 -1000
Organization Wheeler&Wheeler
Message-ID <871pytpeu6.fsf@localhost> (permalink)
References <viao3r$na9e$4@dont-email.me> <memo.20241128220827.12904a@jgd.cix.co.uk> <vib878$pqul$1@dont-email.me>

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Lawrence D'Oliveiro <ldo@nz.invalid> writes:
> IBM had legendary market power, all the way up to monopoly status. 
> Whatever it decreed, its market had to follow.

In the wake of the Future System mid-70s implosion, the head of POK
(high-end mainframe) also convinced corporate to kill the (virtual
machine) VM370 product, shutdown the development group and transfer all
the people to POK to work on MVS/XA (i.e. a lot of XA/370 changes were
to address various bloat&kludges in MVS/370). Come 80s, with 3081 and
MVS/XA, customers weren't converting as planned, continuing to run 3081
370-mode with MVS/370. Amdahl was having more success, it had developed
microcode hypervisor/virtual machine ("multiple domain") support and
able to run both MVS/370 and MVS/XA concurrently on the same (Amdahl)
machine (note Endicott did eventually obtain VM370 product
responsibility for the mid-range 370s, but had to recreate a development
group from scratch).

Amdahl had another advantage, initially 3081 was two processor only and
3081D aggregate MIPS was less than the single processor Amdahl
machine. IBM doubles the processor cache sizes for the 2-CPU 3081K,
having about same aggregate MIPs as Amdahl single CPU .... however at
the time, IBM MVS documents had MVS two-processor (multiprocessor
overhead) support only getting 1.2-1.5 times the throughput of single
processor (aka Amdahl single processor getting full MIPS throughput
while MVS two processor 3081K loosing lots of throughput to
multiprocessor overhead).

POK had done a rudementary virtual software system for MVS/XA testing
... which eventually ships as VM/MA (migration aid) and then VM/SF
(system facility) ... however since 370/XA had been primarily focused to
compensate for MVS issues ... 3081 370/XA required a lot of microcode
tweaks when running in virtual machine mode and 3081 didn't have the
space ... so switching in and out of VM/MA or VM/SF with virtual machine
mode, had a lot of overhead "paging" microcode. It was almost a decade
later before IBM was able to respond to Amdahl's
hypervisor/multiple-domain with 3090 LPAR & PR/SM support.


-- 
virtualization experience starting Jan1968, online at home since Mar1970

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Thread

What is an N-bit machine? jgd@cix.co.uk (John Dallman) - 2024-11-28 15:31 +0000
  Re: What is an N-bit machine? scott@slp53.sl.home (Scott Lurndal) - 2024-11-28 16:33 +0000
  Re: What is an N-bit machine? Michael S <already5chosen@yahoo.com> - 2024-11-28 18:55 +0200
    Re: What is an N-bit machine? John Levine <johnl@taugh.com> - 2024-11-30 02:37 +0000
      Re: What is an N-bit machine? Stephen Fuld <sfuld@alumni.cmu.edu.invalid> - 2024-11-29 22:30 -0800
        Re: What is an N-bit machine? John Levine <johnl@taugh.com> - 2024-11-30 19:40 +0000
          Re: What is an N-bit machine? Michael S <already5chosen@yahoo.com> - 2024-11-30 22:38 +0200
            Re: What is an N-bit machine? "Paul A. Clayton" <paaronclayton@gmail.com> - 2024-12-01 11:23 -0500
              Re: What is an N-bit machine? scott@slp53.sl.home (Scott Lurndal) - 2024-12-01 19:52 +0000
          Re: What is an N-bit machine? mitchalsup@aol.com (MitchAlsup1) - 2024-11-30 22:39 +0000
            Re: What is an N-bit machine? Thomas Koenig <tkoenig@netcologne.de> - 2024-12-01 08:19 +0000
              Re: What is an N-bit machine? anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2024-12-01 08:35 +0000
            Re: What is an N-bit machine? Terje Mathisen <terje.mathisen@tmsw.no> - 2024-12-02 09:48 +0100
              Re: What is an N-bit machine? "Brian G. Lucas" <bagel99@gmail.com> - 2024-12-02 19:56 -0500
                Re: What is an N-bit machine? Stephen Fuld <sfuld@alumni.cmu.edu.invalid> - 2024-12-03 00:01 -0800
              Re: What is an N-bit machine? antispam@fricas.org (Waldek Hebisch) - 2024-12-15 18:20 +0000
      Keeping other stuff with addresses (was: What is an N-bit machine?) anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2024-11-30 06:28 +0000
        Re: Keeping other stuff with addresses (was: What is an N-bit machine?) anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2024-11-30 11:35 +0000
          Re: Keeping other stuff with addresses (was: What is an N-bit machine?) Thomas Koenig <tkoenig@netcologne.de> - 2024-11-30 11:58 +0000
            Re: Keeping other stuff with addresses (was: What is an N-bit machine?) anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2024-11-30 16:57 +0000
              Re: Keeping other stuff with addresses (was: What is an N-bit machine?) Michael S <already5chosen@yahoo.com> - 2024-11-30 19:32 +0200
                Re: Keeping other stuff with addresses (was: What is an N-bit machine?) anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2024-11-30 18:08 +0000
                Re: Keeping other stuff with addresses (was: What is an N-bit machine?) Michael S <already5chosen@yahoo.com> - 2024-11-30 20:28 +0200
                Re: Keeping other stuff with addresses (was: What is an N-bit machine?) anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2024-12-01 09:28 +0000
                Re: Keeping other stuff with addresses (was: What is an N-bit machine?) Thomas Koenig <tkoenig@netcologne.de> - 2024-12-01 14:03 +0000
                Re: Keeping other stuff with addresses David Schultz <david.schultz@earthlink.net> - 2024-12-01 08:15 -0600
                Re: Keeping other stuff with addresses Thomas Koenig <tkoenig@netcologne.de> - 2024-12-01 14:40 +0000
                Re: Keeping other stuff with addresses mitchalsup@aol.com (MitchAlsup1) - 2024-12-04 02:19 +0000
                Re: Keeping other stuff with addresses John Levine <johnl@taugh.com> - 2024-12-04 03:25 +0000
                Re: Keeping other stuff with addresses (was: What is an N-bit machine?) Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-12-01 07:32 -0800
                Re: Keeping other stuff with addresses (was: What is an N-bit machine?) Thomas Koenig <tkoenig@netcologne.de> - 2024-12-01 17:53 +0000
                Re: Keeping other stuff with addresses (was: What is an N-bit machine?) Michael S <already5chosen@yahoo.com> - 2024-12-01 20:05 +0200
                Re: Keeping other stuff with addresses EricP <ThatWouldBeTelling@thevillage.com> - 2024-12-01 18:16 -0500
                Re: Keeping other stuff with addresses (was: What is an N-bit machine?) Brett <ggtgp@yahoo.com> - 2024-12-01 20:02 +0000
                Re: Keeping other stuff with addresses (was: What is an N-bit machine?) Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-12-31 08:54 -0800
                Re: Keeping other stuff with addresses (was: What is an N-bit machine?) Thomas Koenig <tkoenig@netcologne.de> - 2025-01-01 15:28 +0000
                Re: Keeping other stuff with addresses (was: What is an N-bit machine?) Tim Rentsch <tr.17687@z991.linuxsc.com> - 2025-01-01 17:39 -0800
                Re: Keeping other stuff with addresses (was: What is an N-bit machine?) Thomas Koenig <tkoenig@netcologne.de> - 2025-01-02 09:59 +0000
                Re: Keeping other stuff with addresses (was: What is an N-bit machine?) Tim Rentsch <tr.17687@z991.linuxsc.com> - 2025-01-08 10:00 -0800
                Re: Keeping other stuff with addresses (was: What is an N-bit machine?) Thomas Koenig <tkoenig@netcologne.de> - 2025-01-08 19:18 +0000
                Re: Keeping other stuff with addresses (was: What is an N-bit machine?) Tim Rentsch <tr.17687@z991.linuxsc.com> - 2025-01-27 17:05 -0800
                Re: Keeping other stuff with addresses David Brown <david.brown@hesbynett.no> - 2025-01-28 08:30 +0100
                Re: Keeping other stuff with addresses Thomas Koenig <tkoenig@netcologne.de> - 2025-02-02 08:37 +0000
                Re: Keeping other stuff with addresses Terje Mathisen <terje.mathisen@tmsw.no> - 2024-12-02 17:10 +0100
                Re: Keeping other stuff with addresses Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-12-31 08:46 -0800
                Re: Keeping other stuff with addresses (was: What is an N-bit machine?) John Levine <johnl@taugh.com> - 2024-11-30 19:12 +0000
                What is an N-bit machine? anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2024-12-01 08:41 +0000
                Re: What is an N-bit machine? scott@slp53.sl.home (Scott Lurndal) - 2024-12-01 15:52 +0000
                Re: What is an N-bit machine? antispam@fricas.org (Waldek Hebisch) - 2024-12-16 22:39 +0000
                Re: Keeping other stuff with addresses (was: What is an N-bit machine?) Thomas Koenig <tkoenig@netcologne.de> - 2024-11-30 22:06 +0000
                Re: Keeping other stuff with addresses (was: What is an N-bit machine?) anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2024-12-01 08:38 +0000
        Re: Keeping other stuff with addresses (was: What is an N-bit machine?) scott@slp53.sl.home (Scott Lurndal) - 2024-11-30 17:57 +0000
          Re: Keeping other stuff with addresses (was: What is an N-bit machine?) anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2024-12-01 09:38 +0000
        Re: Keeping other stuff with addresses "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-12-01 15:22 -0800
          Re: Keeping other stuff with addresses mitchalsup@aol.com (MitchAlsup1) - 2024-12-02 01:26 +0000
            Re: Keeping other stuff with addresses "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-12-01 20:12 -0800
              Re: Keeping other stuff with addresses "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-12-02 16:54 -0800
                Re: Keeping other stuff with addresses Stefan Monnier <monnier@iro.umontreal.ca> - 2024-12-03 11:51 -0500
                Re: Keeping other stuff with addresses John Levine <johnl@taugh.com> - 2024-12-03 18:19 +0000
                Re: Keeping other stuff with addresses Stefan Monnier <monnier@iro.umontreal.ca> - 2024-12-03 13:46 -0500
                Re: Keeping other stuff with addresses John Levine <johnl@taugh.com> - 2024-12-03 23:33 +0000
                Re: Keeping other stuff with addresses Stefan Monnier <monnier@iro.umontreal.ca> - 2024-12-03 18:52 -0500
                Re: Keeping other stuff with addresses mitchalsup@aol.com (MitchAlsup1) - 2024-12-04 02:36 +0000
                Re: Keeping other stuff with addresses Thomas Koenig <tkoenig@netcologne.de> - 2024-12-04 06:29 +0000
                Re: Keeping other stuff with addresses Stefan Monnier <monnier@iro.umontreal.ca> - 2024-12-04 10:32 -0500
                Re: Keeping other stuff with addresses mitchalsup@aol.com (MitchAlsup1) - 2024-12-04 19:47 +0000
                Re: Keeping other stuff with addresses Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-12-04 15:47 -0800
                Re: Keeping other stuff with addresses scott@slp53.sl.home (Scott Lurndal) - 2024-12-04 16:31 +0000
                Re: bytes, Keeping other stuff with addresses John Levine <johnl@taugh.com> - 2024-12-05 00:39 +0000
                unaligned load/store (was: Re: Keeping other stuff with addresses) Jonathan Thornburg <jonathan@gold.bkis-orchard.net> - 2024-12-21 23:22 +0000
                Re: unaligned load/store mitchalsup@aol.com (MitchAlsup1) - 2024-12-22 01:27 +0000
                Re: unaligned load/store Thomas Koenig <tkoenig@netcologne.de> - 2024-12-22 10:01 +0000
                Re: unaligned load/store anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2024-12-22 11:06 +0000
                Re: unaligned load/store jgd@cix.co.uk (John Dallman) - 2024-12-22 11:42 +0000
                Re: unaligned load/store "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-12-22 19:41 -0800
                Re: unaligned load/store Thomas Koenig <tkoenig@netcologne.de> - 2024-12-22 21:04 +0000
                Re: unaligned load/store mitchalsup@aol.com (MitchAlsup1) - 2024-12-22 23:32 +0000
                Re: unaligned load/store Stefan Monnier <monnier@iro.umontreal.ca> - 2024-12-26 13:38 -0500
                Re: unaligned load/store George Neuner <gneuner2@comcast.net> - 2024-12-26 16:31 -0500
                Re: unaligned load/store mitchalsup@aol.com (MitchAlsup1) - 2024-12-26 21:59 +0000
                Re: unaligned load/store "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-12-26 14:05 -0800
                Re: unaligned load/store (was: Re: Keeping other stuff with addresses) anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2024-12-22 10:33 +0000
                Re: bits and bytes, Keeping other stuff with addresses John Levine <johnl@taugh.com> - 2024-12-04 03:39 +0000
                Re: bits and bytes, Keeping other stuff with addresses Stefan Monnier <monnier@iro.umontreal.ca> - 2024-12-04 10:36 -0500
                Re: Keeping other stuff with addresses mitchalsup@aol.com (MitchAlsup1) - 2024-12-03 19:22 +0000
                Re: Keeping other stuff with addresses "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-12-03 17:03 -0800
                Re: Keeping other stuff with addresses "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-12-03 16:56 -0800
                Re: Keeping other stuff with addresses Stefan Monnier <monnier@iro.umontreal.ca> - 2024-12-04 10:37 -0500
        Re: Keeping other stuff with addresses Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-12-03 17:43 -0800
          Re: Keeping other stuff with addresses mitchalsup@aol.com (MitchAlsup1) - 2024-12-04 02:42 +0000
  Re: What is an N-bit machine? Thomas Koenig <tkoenig@netcologne.de> - 2024-11-28 17:56 +0000
    Re: What is an N-bit machine? mitchalsup@aol.com (MitchAlsup1) - 2024-11-28 19:02 +0000
      Re: What is an N-bit machine? Brett <ggtgp@yahoo.com> - 2024-11-28 19:39 +0000
    Re: What is an N-bit machine? Lawrence D'Oliveiro <ldo@nz.invalid> - 2024-11-28 21:42 +0000
      Re: What is an N-bit machine? jgd@cix.co.uk (John Dallman) - 2024-11-28 22:08 +0000
        Re: What is an N-bit machine? Lynn Wheeler <lynn@garlic.com> - 2024-11-28 12:44 -1000
          Re: What is an N-bit machine? jgd@cix.co.uk (John Dallman) - 2024-11-28 22:58 +0000
          IBM and Amdahl history (Re: What is an N-bit machine?) anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2024-11-29 07:22 +0000
            Re: IBM and Amdahl history (Re: What is an N-bit machine?) Lynn Wheeler <lynn@garlic.com> - 2024-11-29 08:24 -1000
            Re: IBM and Amdahl history (Re: What is an N-bit machine?) scott@slp53.sl.home (Scott Lurndal) - 2024-11-29 18:29 +0000
            Re: IBM and Amdahl history (Re: What is an N-bit machine?) Lynn Wheeler <lynn@garlic.com> - 2024-11-29 11:51 -1000
            Re: IBM and Amdahl history (Re: What is an N-bit machine?) Lawrence D'Oliveiro <ldo@nz.invalid> - 2024-11-29 21:51 +0000
              Re: IBM and Amdahl history (Re: What is an N-bit machine?) scott@slp53.sl.home (Scott Lurndal) - 2024-11-30 17:45 +0000
                Re: IBM and Amdahl history (Re: What is an N-bit machine?) anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2024-11-30 18:19 +0000
                Re: IBM and Amdahl history (Re: What is an N-bit machine?) jgd@cix.co.uk (John Dallman) - 2024-11-30 22:19 +0000
                Re: IBM and Amdahl history (Re: What is an N-bit machine?) Lawrence D'Oliveiro <ldo@nz.invalid> - 2024-11-30 23:21 +0000
        Re: What is an N-bit machine? Lawrence D'Oliveiro <ldo@nz.invalid> - 2024-11-29 02:17 +0000
          Re: What is an N-bit machine? Brett <ggtgp@yahoo.com> - 2024-11-30 01:29 +0000
          Re: market power, What is an N-bit machine? John Levine <johnl@taugh.com> - 2024-11-30 02:42 +0000
          Re: What is an N-bit machine? Lynn Wheeler <lynn@garlic.com> - 2024-11-29 17:42 -1000
  Re: What is an N-bit machine? mitchalsup@aol.com (MitchAlsup1) - 2024-11-28 19:01 +0000
  Re: What is an N-bit machine? Lynn Wheeler <lynn@garlic.com> - 2024-11-28 11:45 -1000
  Re: What is an N-bit machine? anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2024-11-29 08:03 +0000
    Re: What is an N-bit machine? Thomas Koenig <tkoenig@netcologne.de> - 2024-11-29 19:17 +0000
    Re: What is an N-bit machine? Lawrence D'Oliveiro <ldo@nz.invalid> - 2024-12-22 21:37 +0000

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