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Groups > alt.folklore.computers > #213508

Re: S/360 model 20

From Charlie Gibbs <cgibbs@kltpzyxm.invalid>
Newsgroups alt.folklore.computers
Subject Re: S/360 model 20
Date 2020-09-01 04:40 +0000
Organization NewsGuy.com
Message-ID <rikjc82d0e@news4.newsguy.com> (permalink)
References <rif9s1$s59$1@dont-email.me> <rigrfd$qq3$1@gal.iecc.com>

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On 2020-08-30, John Levine <johnl@taugh.com> wrote:

> In article <rif9s1$s59$1@dont-email.me>,
> Dan Espen  <dan1espen@gmail.com> wrote:
>
>> I always thought the variable block sizes on S/360 was a mistake.
>> It put too much complexity into user space.  A pity IBM didn't sectorize
>> all of it's disk on all of it's models from the beginning.
>
> I think it was all part of the expensive memory mindset when the 360
> was designed.

In _The Mythical Man Month_, Fred Brooks discusses the decision to
save 100 bytes by omitting leap year code from the supervisor.

> With CKD disks, the ISAM in-memory index only needed one entry per
> track, or even one per cylinder and the channel program took care
> of finding the right individual record.

It wasn't just memory that was scarce.  CPU cycles were almost as
precious, and the CKD architecture and its search commands allowed
processing to be offloaded onto the channel.  It made sense at the
time, even though it doesn't now.

-- 
/~\  Charlie Gibbs                  |  Microsoft is a dictatorship.
\ /  <cgibbs@kltpzyxm.invalid>      |  Apple is a cult.
 X   I'm really at ac.dekanfrus     |  Linux is anarchy.
/ \  if you read it the right way.  |  Pick your poison.

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Thread

S/360 model 20 Dan Espen <dan1espen@gmail.com> - 2020-08-30 00:27 -0400
  Re: S/360 model 20 John Levine <johnl@taugh.com> - 2020-08-30 18:34 +0000
    Re: S/360 model 20 Dan Espen <dan1espen@gmail.com> - 2020-08-30 15:51 -0400
      Re: modern computers and S/360 model 20 John Levine <johnl@taugh.com> - 2020-08-30 22:07 +0000
        Re: modern computers and S/360 model 20 Dan Espen <dan1espen@gmail.com> - 2020-08-30 18:32 -0400
          Re: modern computers and S/360 model 20 J. Clarke <jclarke.873638@gmail.com> - 2020-08-30 18:38 -0400
            Re: modern computers and S/360 model 20 Dan Espen <dan1espen@gmail.com> - 2020-08-30 20:37 -0400
        Re: modern computers and S/360 model 20 Bob Eager <news0073@eager.cx> - 2020-08-31 08:54 +0000
          Re: paging, modern computers and S/360 model 20 John Levine <johnl@taugh.com> - 2020-08-31 16:36 +0000
            Re: paging, modern computers and S/360 model 20 scott@slp53.sl.home (Scott Lurndal) - 2020-08-31 16:57 +0000
            Re: paging, modern computers and S/360 model 20 Bob Eager <news0073@eager.cx> - 2020-08-31 17:21 +0000
              Re: paging, modern computers and S/360 model 20 scott@slp53.sl.home (Scott Lurndal) - 2020-08-31 18:10 +0000
              Re: paging, modern computers and S/360 model 20 Quadibloc <jsavard@ecn.ab.ca> - 2020-08-31 16:10 -0700
                Re: paging, modern computers and S/360 model 20 Bob Eager <news0073@eager.cx> - 2020-09-01 14:14 +0000
                Re: paging, modern computers and S/360 model 20 Bill Findlay <findlaybill@blueyonder.co.uk> - 2020-09-01 17:41 +0100
                Re: paging, modern computers and S/360 model 20 Bob Eager <news0073@eager.cx> - 2020-09-02 08:34 +0000
          Re: modern computers and S/360 model 20 usenet@only.tnx (Questor) - 2020-09-02 07:04 +0000
    Re: S/360 model 20 Charlie Gibbs <cgibbs@kltpzyxm.invalid> - 2020-09-01 04:40 +0000
      Re: S/360 model 20 Quadibloc <jsavard@ecn.ab.ca> - 2020-08-31 22:10 -0700
        Re: S/360 model 20 Charlie Gibbs <cgibbs@kltpzyxm.invalid> - 2020-09-01 19:09 +0000
          Re: S/360 model 20 Dan Espen <dan1espen@gmail.com> - 2020-09-01 15:41 -0400
            Re: S/360 model 20 Jon Elson <elson@pico-systems.com> - 2020-09-03 10:44 -0500
              Re: S/360 model 20 Dan Espen <dan1espen@gmail.com> - 2020-09-03 11:51 -0400
                Re: S/360 model 20 Niklas Karlsson <anksil@yahoo.se> - 2020-09-03 16:41 +0000
              Re: S/360 model 20 J. Clarke <jclarke.873638@gmail.com> - 2020-09-03 12:46 -0400
                Re: S/360 model 20 drb@ihatespam.msu.edu (Dennis Boone) - 2020-09-03 13:32 -0500
                Re: S/360 model 20 Dan Espen <dan1espen@gmail.com> - 2020-09-03 14:44 -0400
                Re: staying up, S/360 model 20 John Levine <johnl@taugh.com> - 2020-09-03 22:28 +0000
          Re: S/360 model 20 hancock4@bbs.cpcn.com - 2020-09-03 11:09 -0700
            Re: S/360 model 20 Peter Flass <peter_flass@yahoo.com> - 2020-09-03 11:48 -0700
            Re: S/360 model 20 Charlie Gibbs <cgibbs@kltpzyxm.invalid> - 2020-09-03 19:49 +0000
              Re: S/360 model 20 Dave Garland <dave.garland@wizinfo.com> - 2020-09-04 10:06 -0500
                Re: S/360 model 20 Charlie Gibbs <cgibbs@kltpzyxm.invalid> - 2020-09-04 16:13 +0000
            Re: S/360 model 20 J. Clarke <jclarke.873638@gmail.com> - 2020-09-03 17:30 -0400
            Re: S/360 model 20 John Levine <johnl@taugh.com> - 2020-09-03 22:55 +0000
            Re: S/360 model 20 Robin Vowels <robin.vowels@gmail.com> - 2020-09-03 19:44 -0700
              Re: S/360 model 20 Quadibloc <jsavard@ecn.ab.ca> - 2020-09-04 23:27 -0700
      Re: S/360 model 20 hancock4@bbs.cpcn.com - 2020-09-01 11:03 -0700
      Re: S/360 model 20 Jon Elson <elson@pico-systems.com> - 2020-09-03 10:42 -0500
        Re: S/360 model 20 hancock4@bbs.cpcn.com - 2020-09-03 11:12 -0700
          Re: S/360 model 20 Peter Flass <peter_flass@yahoo.com> - 2020-09-03 11:48 -0700
          Re: S/360 model 20 Charlie Gibbs <cgibbs@kltpzyxm.invalid> - 2020-09-03 19:49 +0000
            Re: S/360 model 20 hancock4@bbs.cpcn.com - 2020-09-10 11:37 -0700
              Re: S/360 model 20 Charlie Gibbs <cgibbs@kltpzyxm.invalid> - 2020-09-10 23:34 +0000
                Re: S/360 model 20 Peter Flass <peter_flass@yahoo.com> - 2020-09-10 18:06 -0700
                Re: S/360 model 20 Charlie Gibbs <cgibbs@kltpzyxm.invalid> - 2020-09-11 20:41 +0000
                Re: S/360 model 20 Peter Flass <peter_flass@yahoo.com> - 2020-09-11 16:21 -0700
                Re: S/360 model 20 Terry Kennedy <terry-groups@glaver.org> - 2020-09-11 17:26 -0700
                Re: S/360 model 20 Bob Eager <news0073@eager.cx> - 2020-09-12 09:30 +0000
              Re: S/360 model 20 Quadibloc <jsavard@ecn.ab.ca> - 2020-09-10 20:39 -0700
                Re: S/360 model 20 Quadibloc <jsavard@ecn.ab.ca> - 2020-09-10 20:46 -0700
          Re: S/360 model 20 J. Clarke <jclarke.873638@gmail.com> - 2020-09-03 17:41 -0400
    Re: S/360 model 20 hancock4@bbs.cpcn.com - 2020-09-01 11:00 -0700
      Re: S/360 model 20 Quadibloc <jsavard@ecn.ab.ca> - 2020-09-01 17:05 -0700
        Re: S/360 model 20 J. Clarke <jclarke.873638@gmail.com> - 2020-09-01 20:25 -0400
          Re: S/360 model 20 Quadibloc <jsavard@ecn.ab.ca> - 2020-09-10 20:44 -0700
            Re: S/360 model 20 J. Clarke <jclarke.873638@gmail.com> - 2020-09-11 00:30 -0400
              Re: S/360 model 20 Peter Flass <peter_flass@yahoo.com> - 2020-09-11 06:48 -0700
              Re: S/360 model 20 drb@ihatespam.msu.edu (Dennis Boone) - 2020-09-11 11:02 -0500
                Re: S/360 model 20 Peter Flass <peter_flass@yahoo.com> - 2020-09-11 11:18 -0700
              Re: S/360 model 20 "Kerr-Mudd,John" <notsaying@127.0.0.1> - 2020-10-03 10:29 +0000
                Re: S/360 model 20 Peter Flass <peter_flass@yahoo.com> - 2020-10-03 07:38 -0700
                Re: S/360 model 20 scott@slp53.sl.home (Scott Lurndal) - 2020-10-03 16:17 +0000
                Re: S/360 model 20 drb@ihatespam.msu.edu (Dennis Boone) - 2020-10-04 11:24 -0500
        Re: S/360 model 20 Charlie Gibbs <cgibbs@kltpzyxm.invalid> - 2020-09-02 00:50 +0000
      Re: S/360 model 20 Jon Elson <elson@pico-systems.com> - 2020-09-03 10:51 -0500

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