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=-1.1 required=5.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FROM,HTML_MESSAGE,MAILING_LIST_MULTI, RCVD_IN_DNSWL_NONE autolearn=ham autolearn_force=no version=3.4.4 Received: (qmail 30991 invoked from network); 12 Jul 2020 13:27:30 -0000 Received: from minnie.tuhs.org (45.79.103.53) by inbox.vuxu.org with ESMTPUTF8; 12 Jul 2020 13:27:30 -0000 Received: by minnie.tuhs.org (Postfix, from userid 112) id 9104E94EFD; Sun, 12 Jul 2020 23:27:26 +1000 (AEST) Received: from minnie.tuhs.org (localhost [127.0.0.1]) by minnie.tuhs.org (Postfix) with ESMTP id CB4B194EBC; Sun, 12 Jul 2020 23:26:16 +1000 (AEST) Authentication-Results: minnie.tuhs.org; dkim=pass (2048-bit key; unprotected) header.d=gmail.com header.i=@gmail.com header.b="tkB3BNHa"; dkim-atps=neutral Received: by minnie.tuhs.org (Postfix, from userid 112) id 34F3E94EBC; Sun, 12 Jul 2020 23:26:12 +1000 (AEST) Received: from mail-qt1-f173.google.com (mail-qt1-f173.google.com [209.85.160.173]) by minnie.tuhs.org (Postfix) with ESMTPS id 682A994585; Sun, 12 Jul 2020 23:26:11 +1000 (AEST) Received: by mail-qt1-f173.google.com with SMTP id w27so8006349qtb.7; Sun, 12 Jul 2020 06:26:11 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=97Umw2lMI2ha2TQJjB6NW7fIZbLNLwDDrzZ9ThK7z5M=; b=tkB3BNHaEZz79Ioy8NDwtPz2pWghMhYki5DsYoP72KrnbZePTpQCPHo8VDLA/UDkUV PxnSalu6hHwKpA9Rul1Ier/v3B9VoNMHDbUk06MYxCKXTv54wqZMAvMubdDSPYnOWTRw 5JkciZFF3ShZ7xpKCXhyBj6qeLNbtPR7lvZak5n6m0BJ1oJ8SKzYV4R4hrmKjm2AQoK0 TDjwM1PbOu/k+EKcif3foANBq9vkJ81K0Obzv4yiSmBmHKWXR8kwytlgm1kiNltVB8ig 8RGdXZ00YpwkaO0C91HiScmCCjJ9kpZSQ8da/a6hICMMauFUh1BFmjFUghxchTvGA5Iu XH0Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=97Umw2lMI2ha2TQJjB6NW7fIZbLNLwDDrzZ9ThK7z5M=; b=I8MOl0WVTJpJWK3UuSqkAGUf0Kd/J5/OeH8JdRRtC1xLN/YQdeLIrxVS2wAPYmMofB PcsWWUj33toPN8fwUUwqsHbVn/PLYmOWosMveEl27vcLYkZTYyHSp9aHCkkz3Ql8VjC5 5VxynvBKoWjNEyD89GhppiXUK0ZEhnJWVSbY4VmJU2SQbbsmaC5Bw1XjPFkRiIZrHiAb sAX9uFl4Ygsr8PJctoDYpT07jK8UNL+HHABiLCUSjabiBmNQrN82GHXGJRQUdiKODMSR QIn7SycHgRoXga7uArmMhPfwCs4eWT8oY85FvMjPE52Hmq0wl706qww2NtcKqtnmgKKM rJ4A== X-Gm-Message-State: AOAM533PSEgvJ1m+BWyeWvBknSOiLmWgv62ORYFKGLG1qUFKhh+0tDzv rjgxqV7GNu2xYSuRCVzdDdwOpViWrIjAu4LjcgsixMCh X-Google-Smtp-Source: ABdhPJxCdx5cyVXfhxCcp9Z5973fgO6gQUgH8unkTgkz7yH8FAVSilHYk5u2EpB++l7edy2rXYUCGd17WpHPZASbHvo= X-Received: by 2002:ac8:1a0f:: with SMTP id v15mr81226791qtj.136.1594560370424; Sun, 12 Jul 2020 06:26:10 -0700 (PDT) MIME-Version: 1.0 References: <20200711203020.GA1884@minnie.tuhs.org> <202007120222.06C2MtdJ140032@tahoe.cs.Dartmouth.EDU> <738ab925-586b-4921-b891-a4ec20348d4c@localhost> In-Reply-To: <738ab925-586b-4921-b891-a4ec20348d4c@localhost> From: Dan Cross Date: Sun, 12 Jul 2020 09:25:34 -0400 Message-ID: To: =?UTF-8?Q?Michael_Kj=C3=B6rling?= Content-Type: multipart/alternative; boundary="00000000000073bf6605aa3e84e9" Subject: Re: [TUHS] Monitoring by loudspeaker (was: BTL pranks) X-BeenThere: tuhs@minnie.tuhs.org X-Mailman-Version: 2.1.26 Precedence: list List-Id: The Unix Heritage Society mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Computer Old Farts Followers , The Eunuchs Hysterical Society Errors-To: tuhs-bounces@minnie.tuhs.org Sender: "TUHS" --00000000000073bf6605aa3e84e9 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Sun, Jul 12, 2020 at 7:59 AM Michael Kj=C3=B6rling wrote: > (This should probably be on COFF because I don't think this has much > to do with UNIX.) > > > On 11 Jul 2020 22:22 -0400, from doug@cs.dartmouth.edu (Doug McIlroy): > > a loudspeaker hooked to the low-order bit of the accumulator played > > gentle white noise in the background. The noise would turn into a > > shriek when the computer got into a tight loop, > > How did that work? I can see how tying the low-order bit of the > accumulator to a loudspeaker would generate white noise as the > computer is doing work; but I fail to see how doing so would even > somewhat reliably generate a shrieking sound when the computer is in a > tight loop. Please, enlighten me. :-) > I would imagine a cap as a low-pass filter and a transistor as a poor-man's analog comparator triggering a tape player on loop. - Dan C. --00000000000073bf6605aa3e84e9 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable
On Sun, Jul 12, 2020 at 7:59 AM Michael K= j=C3=B6rling <michael@kjorling.se= > wrote:
(This should probably be on COFF because I don&#= 39;t think this has much
to do with UNIX.)


On 11 Jul 2020 22:22 -0400, from doug@cs.dartmouth.edu (Doug McIlroy):
> a loudspeaker hooked to the low-order bit of the accumulator played > gentle white noise in the background. The noise would turn into a
> shriek when the computer got into a tight loop,

How did that work? I can see how tying the low-order bit of the
accumulator to a loudspeaker would generate white noise as the
computer is doing work; but I fail to see how doing so would even
somewhat reliably generate a shrieking sound when the computer is in a
tight loop. Please, enlighten me. :-)

I= would imagine a cap as a low-pass filter and a transistor as a poor-man= 9;s analog comparator triggering a tape player on loop.

=C2=A0 =C2=A0 =C2=A0 =C2=A0 - Dan C.

--00000000000073bf6605aa3e84e9--