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, RCVD_IN_DNSWL_NONE autolearn=ham autolearn_force=no version=3.4.4 Received: (qmail 11053 invoked from network); 12 Jul 2020 15:28:16 -0000 Received: from minnie.tuhs.org (45.79.103.53) by inbox.vuxu.org with ESMTPUTF8; 12 Jul 2020 15:28:16 -0000 Received: by minnie.tuhs.org (Postfix, from userid 112) id 41AA094ED7; Mon, 13 Jul 2020 01:28:14 +1000 (AEST) Received: from minnie.tuhs.org (localhost [127.0.0.1]) by minnie.tuhs.org (Postfix) with ESMTP id 094F294EC0; Mon, 13 Jul 2020 01:27:40 +1000 (AEST) Received: by minnie.tuhs.org (Postfix, from userid 112) id 0531F94EC0; Mon, 13 Jul 2020 01:27:34 +1000 (AEST) X-Greylist: delayed 1746 seconds by postgrey-1.36 at minnie.tuhs.org; Mon, 13 Jul 2020 01:27:31 AEST Received: from fuz.su (fuz.su [5.135.162.8]) by minnie.tuhs.org (Postfix) with ESMTPS id EEDB594EBC; Mon, 13 Jul 2020 01:27:31 +1000 (AEST) Received: from fuz.su (localhost [127.0.0.1]) by fuz.su (8.15.2/8.15.2) with ESMTPS id 06CEwMgQ073112 (version=TLSv1.3 cipher=TLS_AES_256_GCM_SHA384 bits=256 verify=NO); Sun, 12 Jul 2020 16:58:22 +0200 (CEST) (envelope-from fuz@fuz.su) Received: (from fuz@localhost) by fuz.su (8.15.2/8.15.2/Submit) id 06CEwMhe073111; Sun, 12 Jul 2020 16:58:22 +0200 (CEST) (envelope-from fuz) Date: Sun, 12 Jul 2020 16:58:22 +0200 From: Robert Clausecker To: coff@tuhs.org, tuhs@tuhs.org Message-ID: <20200712145822.GA72854@fuz.su> References: <20200711203020.GA1884@minnie.tuhs.org> <202007120222.06C2MtdJ140032@tahoe.cs.Dartmouth.EDU> <738ab925-586b-4921-b891-a4ec20348d4c@localhost> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <738ab925-586b-4921-b891-a4ec20348d4c@localhost> 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: , Errors-To: tuhs-bounces@minnie.tuhs.org Sender: "TUHS" When the computer is in a tight endless loop, the accumulator takes the same series of values every time it's in the loop. Thus, instead of white noise you get a sound whose frequency is the clock frequency of the machine divided by the number of cycles spent by one loop iteration. That's how you know that the machine is stuck in an endless loop: if it was doing something useful, the values would change every iteration and you would get white noise again. Yours, Robert C On Sun, Jul 12, 2020 at 11:58:11AM +0000, Michael Kjörling 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. :-) > > -- > Michael Kjörling • https://michael.kjorling.se • michael@kjorling.se > “Remember when, on the Internet, nobody cared that you were a dog?” > -- () ascii ribbon campaign - for an 8-bit clean world /\ - against html email - against proprietary attachments