From mboxrd@z Thu Jan  1 00:00:00 1970
X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on inbox.vuxu.org
X-Spam-Level: 
X-Spam-Status: No, score=-1.0 required=5.0 tests=MAILING_LIST_MULTI
	autolearn=ham autolearn_force=no version=3.4.4
Received: (qmail 31514 invoked from network); 13 Dec 2022 14:31:30 -0000
Received: from minnie.tuhs.org (50.116.15.146)
  by inbox.vuxu.org with ESMTPUTF8; 13 Dec 2022 14:31:30 -0000
Received: from minnie.tuhs.org (localhost [IPv6:::1])
	by minnie.tuhs.org (Postfix) with ESMTP id 08E5A423D1;
	Wed, 14 Dec 2022 00:31:25 +1000 (AEST)
Received: from freefriends.org (freefriends.org [96.88.95.60])
	by minnie.tuhs.org (Postfix) with ESMTPS id 4F9C8423CD
	for <tuhs@tuhs.org>; Wed, 14 Dec 2022 00:31:20 +1000 (AEST)
X-Envelope-From: arnold@skeeve.com
Received: from freefriends.org (freefriends.org [96.88.95.60])
	by freefriends.org (8.14.7/8.14.7) with ESMTP id 2BDEVD2H018960
	(version=TLSv1/SSLv3 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT);
	Tue, 13 Dec 2022 07:31:13 -0700
Received: (from arnold@localhost)
	by freefriends.org (8.14.7/8.14.7/Submit) id 2BDEVCls018959;
	Tue, 13 Dec 2022 07:31:12 -0700
From: arnold@skeeve.com
Message-Id: <202212131431.2BDEVCls018959@freefriends.org>
X-Authentication-Warning: frenzy.freefriends.org: arnold set sender to arnold@skeeve.com using -f
Date: Tue, 13 Dec 2022 07:31:12 -0700
To: jpl.jpl@gmail.com, douglas.mcilroy@dartmouth.edu
References: <CAMYpm85A7ACZ1mYRjrKDNNRVPh-wnZVXAN=bkjr6FXHeeM2suw@mail.gmail.com>
 <alpine.BSF.2.21.9999.2212131444030.1473@aneurin.horsfall.org>
 <CAC0cEp_Mg3yBqbZsWwpNkk01cXsUDWwk1wuNq_TfB_rUa_iukw@mail.gmail.com>
 <CAKH6PiVsYUr+sSVBWSjmETZcfqxnuM_XW1d_V5y=m-k5gfAGBg@mail.gmail.com>
In-Reply-To: <CAKH6PiVsYUr+sSVBWSjmETZcfqxnuM_XW1d_V5y=m-k5gfAGBg@mail.gmail.com>
User-Agent: Heirloom mailx 12.5 7/5/10
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Transfer-Encoding: 7bit
Message-ID-Hash: 274WGJWZR23TCUJZWNFSFTQAFCQSVHCF
X-Message-ID-Hash: 274WGJWZR23TCUJZWNFSFTQAFCQSVHCF
X-MailFrom: arnold@skeeve.com
X-Mailman-Rule-Misses: dmarc-mitigation; no-senders; approved; emergency; loop; banned-address; member-moderation; header-match-tuhs.tuhs.org-0; nonmember-moderation; administrivia; implicit-dest; max-recipients; max-size; news-moderation; no-subject; digests; suspicious-header
CC: tuhs@tuhs.org
X-Mailman-Version: 3.3.6b1
Precedence: list
Subject: [TUHS] Re: Clever code
List-Id: The Unix Heritage Society mailing list <tuhs.tuhs.org>
Archived-At: <https://www.tuhs.org/mailman3/hyperkitty/list/tuhs@tuhs.org/message/274WGJWZR23TCUJZWNFSFTQAFCQSVHCF/>
List-Archive: <https://www.tuhs.org/mailman3/hyperkitty/list/tuhs@tuhs.org/>
List-Help: <mailto:tuhs-request@tuhs.org?subject=help>
List-Owner: <mailto:tuhs-owner@tuhs.org>
List-Post: <mailto:tuhs@tuhs.org>
List-Subscribe: <mailto:tuhs-join@tuhs.org>
List-Unsubscribe: <mailto:tuhs-leave@tuhs.org>

Douglas McIlroy <douglas.mcilroy@dartmouth.edu> wrote:

> Apropos of accessing rotating storage, John Kelly used to describe the
> Packard-Bell 250, which had a delay-line memory, as a machine where
> addresses refer to time rather than space.
>
> The PB 250 had two instruction-sequencing modes. In one mode, each
> instruction included the address of its successor. In the other mode,
> whatever popped out the delay line when the current instruction
> completed would be executed next.
>
> Doug

For us (relative) youngsters, can you explain some more how delay
line memory worked? The second mode you describe sounds like it
would be impossible to use if you wanted repeatable, reproducible
runs of your program.

Thanks,

Arnold