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=-0.8 required=5.0 tests=DKIM_ADSP_CUSTOM_MED, DKIM_INVALID,DKIM_SIGNED,FREEMAIL_FROM,HTML_MESSAGE,MAILING_LIST_MULTI autolearn=ham autolearn_force=no version=3.4.4 Received: (qmail 23141 invoked from network); 15 Dec 2022 18:09:30 -0000 Received: from minnie.tuhs.org (50.116.15.146) by inbox.vuxu.org with ESMTPUTF8; 15 Dec 2022 18:09:30 -0000 Received: from minnie.tuhs.org (localhost [IPv6:::1]) by minnie.tuhs.org (Postfix) with ESMTP id A40D142499; Fri, 16 Dec 2022 04:09:26 +1000 (AEST) Received: from mail-ot1-f44.google.com (mail-ot1-f44.google.com [209.85.210.44]) by minnie.tuhs.org (Postfix) with ESMTPS id C5ABF42399 for ; Fri, 16 Dec 2022 04:09:22 +1000 (AEST) Received: by mail-ot1-f44.google.com with SMTP id m6-20020a9d7e86000000b0066ec505ae93so4058562otp.9 for ; Thu, 15 Dec 2022 10:09:22 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:from:to:cc:subject:date:message-id:reply-to; bh=vqUQbpZGPqsMDMoR7OEQyVa3/O8rDZd8xSzHDoWIrvM=; b=bOZZYUPr94eE6QKnPgWw3APlDPVo9VCfkfA2kIXyqARCIeFXof0jFOGGAa4lmoykJs rbknaVqpM+SMSlvHKaWbYoQmdKUJJcBWpDfhnBmayscQeGa5fsCLRFf0rOKXSnUXChdE Ia/VraSXLrFhBS0kieRlEpmBEbKjQccZuuWOUKoD+3Fw/ccCGqX/ucbaUBImVNCIliro 7iR0HDHWrcm1wLvID+8Q4mR56UjF1wV8eYzNikN7eFzvCoHDGJOAunXO22B7IHkjD85G AeYU+Gv/rG44CXf+gG3KfvQawnBDilgdA6Ur5RNP+YLkqc3g/cEgDX42RVmzD7092sDt j33Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=vqUQbpZGPqsMDMoR7OEQyVa3/O8rDZd8xSzHDoWIrvM=; b=H5i6Q75TKEno7Ow5DcmMjQ6mOLapWSDU6fcDiyRp+5bKhBFQzmTZa60ClIsmzJAJSd xCBJ2+m2SC+yPvQPwpJOxsFWYXKKZSrCegPsOzGZSL5akrtKZc8z5MSsP3kQ97HcZdUT uUX+lS92Pn5M6K738fVddffFc6M6rEXD7nTgrQf9GxTKKM8drSJSLtP9orEqXD0ucxSP 8F+EIQRyN2ggynu9qwLzoHAEPs+dQV+xUQ52wcPI1KiQga4rQ1rHCsTJ254yyGAUYGC6 0+9n8NOmjHekSOUD3gATA3vEaW2HW6jhiZCfNrS9gkWG3Y02i4mHQhCinwvxiayjzmS6 fV+w== X-Gm-Message-State: ANoB5pksIgSTw+gvq4OL28q0kR6kPVQng/x2fRgqnbm0bSzmjxwdLGT3 38rXiS4qF/J4xPOrZVUkdrnd2DWb0+gqRb2QupziARlJvZEhmQ== X-Google-Smtp-Source: AA0mqf5l4PETCf2PMfKQVYyxbe4gqAWLV23Fv7O9qVwJIDb2evPzBvJharmPhdcPWBN1iX5jx4ExyoHeP4PjDi7U1Mc= X-Received: by 2002:a05:6830:30a5:b0:670:7420:e4ad with SMTP id g37-20020a05683030a500b006707420e4admr1846537ots.56.1671127702008; Thu, 15 Dec 2022 10:08:22 -0800 (PST) MIME-Version: 1.0 References: <202212131431.2BDEVCls018959@freefriends.org> In-Reply-To: From: Marc Donner Date: Thu, 15 Dec 2022 13:08:10 -0500 Message-ID: To: Douglas McIlroy Content-Type: multipart/alternative; boundary="0000000000000d789205efe1bd68" Message-ID-Hash: CP4HDQYJLT4N2QFZHYRQCZN2WSSJNQHN X-Message-ID-Hash: CP4HDQYJLT4N2QFZHYRQCZN2WSSJNQHN X-MailFrom: marc.donner@gmail.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 Archived-At: List-Archive: List-Help: List-Owner: List-Post: List-Subscribe: List-Unsubscribe: --0000000000000d789205efe1bd68 Content-Type: text/plain; charset="UTF-8" Here is a page from the Computer History Museum on the topic: https://www.computerhistory.org/revolution/memory-storage/8/309 about halfway down the page is a nice schematic. ===== nygeek.net mindthegapdialogs.com/home On Thu, Dec 15, 2022 at 1:06 PM Marc Donner wrote: > Further on delay line storage: > > Physically one of the most common ones was a cylinder of liquid mercury. > There was a device at one end for introducing pressure waves into the > mercury (think loudspeaker) and a device at the other end for measuring the > pressure waves arriving (think microphone). The pulses that came off the > microphone end were then fed back to the loudspeaker end, after being > cleaned up. > ===== > nygeek.net > mindthegapdialogs.com/home > > > On Tue, Dec 13, 2022 at 10:12 AM Douglas McIlroy < > douglas.mcilroy@dartmouth.edu> wrote: > >> A delay line is logically like a drum, with circulating data that is >> accessible only at one point on the circle. A delay line was >> effectively a linear channel along which a train of data pulses was >> sent. Pulses received at the far end were reshaped electronically. and >> reinjected at the sending end. One kind of delay line was a mercury >> column that carried acoustic pulses.. The PB 250 delay line was >> magnetostrictive (a technology I know nothing about). >> >> If instruction timing is known, then the next instruction to appear is >> predictable. The only caveat is that instruction times should not be >> data-dependent. You can lay out sequential code along the circle as >> long as no instruction steps on one already placed. When that happens >> you must switch modes to jump to an open spot, or perhaps insert nops >> to jiggle the layout. >> >> Doug >> >> On Tue, Dec 13, 2022 at 9:31 AM wrote: >> > >> > Douglas McIlroy 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 >> > --0000000000000d789205efe1bd68 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable
Here is a page from the Computer History Museum= on the topic:=C2=A0https://www.computerhistory.org/revolution/memory-stor= age/8/309

about halfway down the = page is a nice schematic.


On Thu, Dec 15= , 2022 at 1:06 PM Marc Donner <= marc.donner@gmail.com> wrote:
Further on delay line stor= age:

Physically one of the most common= ones was a cylinder of liquid mercury.=C2=A0 There was a device at one end= for introducing pressure waves into the mercury (think loudspeaker) and a = device at the other end for measuring the pressure waves arriving (think mi= crophone).=C2=A0 The pulses that came off the microphone end were then fed = back to the loudspeaker end, after being cleaned up.

On Tue, Dec 13, 2022 at 10:12 AM Douglas McIlroy &= lt;dougl= as.mcilroy@dartmouth.edu> wrote:
A delay line is logically like a drum, with circula= ting data that is
accessible only at one point on the circle. A delay line was
effectively a linear channel along which a train of data pulses was
sent. Pulses received at the far end were reshaped electronically. and
reinjected at the sending end. One kind of delay line was a mercury
column that carried acoustic pulses.. The PB 250 delay line was
magnetostrictive (a technology I know nothing about).

If instruction timing is known, then the next instruction to appear is
predictable. The only caveat is that instruction times should not be
data-dependent. You can lay out sequential code along the circle as
long as no instruction steps on one already placed. When that happens
you must switch modes to jump to an open spot, or perhaps insert nops
to jiggle the layout.

Doug

On Tue, Dec 13, 2022 at 9:31 AM <arnold@skeeve.com> wrote:
>
> Douglas McIlroy <douglas.mcilroy@dartmouth.edu> wrote:
>
> > Apropos of accessing rotating storage, John Kelly used to describ= e the
> > Packard-Bell 250, which had a delay-line memory, as a machine whe= re
> > addresses refer to time rather than space.
> >
> > The PB 250 had two instruction-sequencing modes. In one mode, eac= h
> > instruction included the address of its successor. In the other m= ode,
> > 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
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