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Article #625544Re: PDP-10 addressing, PDP 11/40 system manual
From: Peter Flass
Date: Sun, 12 Aug 2018 11:20
Date: Sun, 12 Aug 2018 11:20
31 lines
3117 bytes
3117 bytes
Quadibloc <jsa...@ecn.ab.ca> wrote: > On Saturday, August 11, 2018 at 9:23:08 AM UTC-6, John Levine wrote: >> In article <1173318279.555679658.757...@news.eternal-september.org>, >> Peter Flass <peter...@yahoo.com> wrote: >>> I was >>> sorry when it was canceled, although I suspect it would have been difficult >>> to expand the architecture to larger memory sizes. > >> We don't have to guess. They did expand the addressing for the DEC-20 >> and it was pretty ugly. The extra address bits were called the >> section number, with some addressing being within the current section >> and some being global. TOPS-20 supported it but I don't recall many >> programs using it. > > The Sigma 9 from Xerox/SDS also took an existing architecture with a full-length > address in the instruction, and modified it to use more memory than that address > could support. > > I think it was ugly too; but I suppose that it could still be said that if the > memory expansion method actually used was a kludge, that doesn't prove th at > something better might not be possible. > The Sigma address space was limited by the use of memory map registers instead of segment and page tables (unless the 9 did something with this too). The address space was plenty big enough for programs of the time, but big databases, photos, or videos would probably have been a stretch. -- Pete
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X-Received: by 2002:a6b:9189:: with SMTP id t131-v6mr6071119iod.41.1534072823899; Sun, 12 Aug 2018 04:20:23 -0700 (PDT) X-BeenThere: alt.folklore.computers@googlegroups.com Received: by 2002:a24:f70d:: with SMTP id x13-v6ls882662ith.5.gmail; Sun, 12 Aug 2018 04:20:23 -0700 (PDT) X-Received: by 2002:a24:dd0d:: with SMTP id t13-v6mr1635736itf.6.1534072823229; Sun, 12 Aug 2018 04:20:23 -0700 (PDT) Path: mbox-mo1.pugleaf.net!g5-v6ni2608iti.0!nntp.google.com!border1.nntp.dca1.giganews.com!nntp.giganews.com!goblin2!goblin1!goblin.stu.neva.ru!eternal-september.org!feeder.eternal-september.org!reader02.eternal-september.org!.POSTED!not-for-mail From: Peter Flass <peter...@yahoo.com> Newsgroups: alt.folklore.computers Subject: Re: PDP-10 addressing, PDP 11/40 system manual Date: Sun, 12 Aug 2018 07:20:22 -0400 Organization: A noiseless patient Spider Lines: 31 Message-ID: <1328179290.555765099.832658.peter_flass-yahoo.com@news.eternal-september.org> References: <21aaeee8-c41a-4442-a4eb-ea6a29b1e4f1@googlegroups.com> <mddh8k2vyfh.fsf@panix5.panix.com> <ft6gi3F3aanU11@mid.individual.net> <1173318279.555679658.757757.peter_flass-yahoo.com@news.eternal-september.org> <pkmv0r$2bhi$1@gal.iecc.com> <0897e059-0b26-4334-82ff-5c0b2253a89e@googlegroups.com> Mime-Version: 1.0 Injection-Info: reader02.eternal-september.org; posting-host="c434ae82c98b76a68e612bc442a5ce12"; logging-data="9987"; mail-complaints-to="ab...@eternal-september.org"; posting-account="U2FsdGVkX18YGHgRQg0mlQi9+TmnWUDs" User-Agent: NewsTap/5.3.1 (iPad) Cancel-Lock: sha1:1sEGY62QeeE92hKMkhhoKlh2/tg= sha1:11pYfLru8bZhWFJ+aSukIBhhBew= Bytes: 2741 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit