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Re: Y3K for PDP-11 Operating Systems

From vandys@vsta.org
Newsgroups comp.os.vms, alt.sys.pdp11, comp.sys.dec, vmsnet.pdp-11
Subject Re: Y3K for PDP-11 Operating Systems
Date 2011-05-10 00:12 +0000
Message-ID <92re7gF8btU1@mid.individual.net> (permalink)
References (15 earlier) <alpine.LFD.2.00.1105090938080.19900@libra.gmcl.internal> <92r5ntFf3hU1@mid.individual.net> <iq9off$af6$1@Iltempo.Update.UU.SE> <92raajFe87U1@mid.individual.net> <iq9ssn$bri$1@Iltempo.Update.UU.SE>

Cross-posted to 4 groups.

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In alt.sys.pdp11 Johnny Billquist <bqt@softjar.se> wrote:
> I know that for some things, actually coding using more primitive 
> instructions on the (older) VAXen turned out to be faster than to use 
> the fancy instructions, but I would not have thought that was true for 
> things like MOVC or LOCC, but I might very well be wrong.

I'm pretty sure we ended up with a hand coded bcopy() back in the day.
It might've been that we could do optional initial odd, and then move
as words.  I think I heard that later Vaxen microcode would do that too.

>  (The big win, however, was 
> obviously the loads of actual code needed to do a context switch which 
> was reduced to just a few bytes on a VAX. :-) )

I'm pretty sure I remember that BSD on the Vax never ended up using
the high level task instructions.  I can remember trying to make it
line up, and ending up deciding it cost more than it saved.

No doubt VMS did, as otherwise, well, what was the point? :->

This all dribbles back to that old RISC versus CISC argument.  I think the
MIPS context switching I coded was faster than anything comparable on a x86
or Vax.  OTOH, MIPS was never able to beat the TLB miss performance of the
x86.  The ultimate (implied) instruction!

-- 
Andy Valencia
Home page: http://www.vsta.org/andy/
To contact me: http://www.vsta.org/contact/andy.html

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Thread

Re: Y3K for PDP-11 Operating Systems koehler@eisner.nospam.encompasserve.org (Bob Koehler) - 2011-05-03 12:51 -0500
  Re: Y3K for PDP-11 Operating Systems Henry Crun <mike@rechtman.com> - 2011-05-03 21:39 +0300
    Re: Y3K for PDP-11 Operating Systems onedbguru <onedbguru@yahoo.com> - 2011-05-03 15:52 -0700
      Re: Y3K for PDP-11 Operating Systems billig999@cs.uofs.edu (Bill Gunshannon) - 2011-05-04 00:07 +0000
        Re: Y3K for PDP-11 Operating Systems "Richard B. Gilbert" <rgilbert88@comcast.net> - 2011-05-04 01:16 -0400
          Re: Y3K for PDP-11 Operating Systems billg999@cs.uofs.edu (Bill Gunshannon) - 2011-05-04 13:01 +0000
            Re: Y3K for PDP-11 Operating Systems "Richard B. Gilbert" <rgilbert88@comcast.net> - 2011-05-04 10:19 -0400
              Re: Y3K for PDP-11 Operating Systems kludge@panix.com (Scott Dorsey) - 2011-05-04 10:58 -0400
              Re: Y3K for PDP-11 Operating Systems billg999@cs.uofs.edu (Bill Gunshannon) - 2011-05-04 16:33 +0000
                Re: Y3K for PDP-11 Operating Systems "Richard B. Gilbert" <rgilbert88@comcast.net> - 2011-05-04 21:51 -0400
                Re: Y3K for PDP-11 Operating Systems G Cornelius <cornelius@eisner.decus.org> - 2011-05-06 13:08 -0500
                Re: Y3K for PDP-11 Operating Systems "Richard B. Gilbert" <rgilbert88@comcast.net> - 2011-05-06 14:47 -0400
                Re: Y3K for PDP-11 Operating Systems Johnny Billquist <bqt@update.uu.se> - 2011-05-06 16:13 -0600
                Re: Y3K for PDP-11 Operating Systems Rich Alderson <news@alderson.users.panix.com> - 2011-05-07 21:00 -0400
                Re: Y3K for PDP-11 Operating Systems Johnny Billquist <bqt@softjar.se> - 2011-05-07 19:51 -0600
                Re: Y3K for PDP-11 Operating Systems "Richard B. Gilbert" <rgilbert88@comcast.net> - 2011-05-08 07:19 -0400
                Re: Y3K for PDP-11 Operating Systems Rich Alderson <news@alderson.users.panix.com> - 2011-05-09 17:32 -0400
                Re: Y3K for PDP-11 Operating Systems Rob Brown <mylastname@gmcl.com> - 2011-05-09 09:40 -0600
                Re: Y3K for PDP-11 Operating Systems Johnny Billquist <bqt@softjar.se> - 2011-05-09 09:43 -0600
                Re: Y3K for PDP-11 Operating Systems vandys@vsta.org - 2011-05-09 21:47 +0000
                Re: Y3K for PDP-11 Operating Systems Johnny Billquist <bqt@softjar.se> - 2011-05-09 16:05 -0600
                Re: Y3K for PDP-11 Operating Systems vandys@vsta.org - 2011-05-09 23:05 +0000
                Re: Y3K for PDP-11 Operating Systems Johnny Billquist <bqt@softjar.se> - 2011-05-09 17:20 -0600
                Re: Y3K for PDP-11 Operating Systems vandys@vsta.org - 2011-05-10 00:12 +0000
                Re: Y3K for PDP-11 Operating Systems Johnny Billquist <bqt@softjar.se> - 2011-05-09 19:36 -0600
                Re: Y3K for PDP-11 Operating Systems glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2011-05-10 02:01 +0000
                Re: Y3K for PDP-11 Operating Systems koehler@eisner.nospam.encompasserve.org (Bob Koehler) - 2011-05-10 08:31 -0500
                Re: Y3K for PDP-11 Operating Systems John Wallace <johnwallace4@yahoo.co.uk> - 2011-05-10 09:56 -0700
                Re: Y3K for PDP-11 Operating Systems koehler@eisner.nospam.encompasserve.org (Bob Koehler) - 2011-05-10 12:50 -0500
                Re: Y3K for PDP-11 Operating Systems G Cornelius <cornelius@eisner.decus.org> - 2011-05-11 11:04 -0500
            Re: Y3K for PDP-11 Operating Systems Johnny Billquist <bqt@softjar.se> - 2011-05-04 10:02 -0700
            Re: Y3K for PDP-11 Operating Systems koehler@eisner.nospam.encompasserve.org (Bob Koehler) - 2011-05-04 12:20 -0500
            [OT] Architectures, was: Re: Y3K for PDP-11 Operating Systems Simon Clubley <clubley@remove_me.eisner.decus.org-Earth.UFP> - 2011-05-04 17:23 +0000
            Re: Y3K for PDP-11 Operating Systems glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2011-05-04 18:10 +0000
              Re: Y3K for PDP-11 Operating Systems John Wallace <johnwallace4@yahoo.co.uk> - 2011-05-04 12:21 -0700
              Re: Y3K for PDP-11 Operating Systems MetaEd <metaed@gmail.com> - 2011-05-04 15:06 -0700
                Re: Y3K for PDP-11 Operating Systems Johnny Billquist <bqt@softjar.se> - 2011-05-04 20:17 -0700
            Re: Y3K for PDP-11 Operating Systems koehler@eisner.nospam.encompasserve.org (Bob Koehler) - 2011-05-10 08:20 -0500
            Re: Y3K for PDP-11 Operating Systems koehler@eisner.nospam.encompasserve.org (Bob Koehler) - 2011-05-10 08:29 -0500
              Re: Y3K for PDP-11 Operating Systems Johnny Billquist <bqt@softjar.se> - 2011-05-10 09:29 -0600
                Re: Y3K for PDP-11 Operating Systems G Cornelius <cornelius@eisner.decus.org> - 2011-05-10 12:16 -0500
            Re: Y3K for PDP-11 Operating Systems koehler@eisner.nospam.encompasserve.org (Bob Koehler) - 2011-05-10 12:45 -0500
              Re: Y3K for PDP-11 Operating Systems Johnny Billquist <bqt@softjar.se> - 2011-05-10 15:34 -0600
            Re: Y3K for PDP-11 Operating Systems koehler@eisner.nospam.encompasserve.org (Bob Koehler) - 2011-05-10 12:58 -0500
              Re: Y3K for PDP-11 Operating Systems Johnny Billquist <bqt@softjar.se> - 2011-05-10 15:36 -0600

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