From mboxrd@z Thu Jan 1 00:00:00 1970 From: crossd at gmail.com (Dan Cross) Date: Sun, 12 Jul 2020 09:25:34 -0400 Subject: [COFF] [TUHS] Monitoring by loudspeaker (was: BTL pranks) In-Reply-To: <738ab925-586b-4921-b891-a4ec20348d4c@localhost> References: <20200711203020.GA1884@minnie.tuhs.org> <202007120222.06C2MtdJ140032@tahoe.cs.Dartmouth.EDU> <738ab925-586b-4921-b891-a4ec20348d4c@localhost> Message-ID: On Sun, Jul 12, 2020 at 7:59 AM 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 at 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. -------------- next part -------------- An HTML attachment was scrubbed... URL: