cvs commit: src/sys/kern subr_param.c

[Kevin Oberman]

> Date: Mon, 8 Nov 2004 18:50:33 +0000
> From: Paul Richards <paul at originative.co.uk>
> Sender: owner-cvs-all at freebsd.org
> 
> On Sat, Nov 06, 2004 at 04:03:12PM -0800, Kris Kennaway wrote:
> > On Sat, Nov 06, 2004 at 03:50:06PM -0800, Nate Lawson wrote:
> > 
> > > I was traveling out of the country so I didn't get a chance to comment. 
> > >  The two caveats I'm aware of is a slight loss in processes that are 
> > > CPU bound and an audio hum from ACPI CPU idling.  The latter is rather 
> > > interesting actually.  At hz=100, it's just a quiet low buzz but at 
> > > 1000, it is readily audible on many laptops and annoying.  Windows uses 
> > > hz=1000 too and has the same problem.  I believe it's related to the 
> > > capacitors and other devices charging/discharging when clocks are stopped.
> > 
> > Can we play music by modulating the value of hz? :)
> 
> I remember some code for the Commodore Pets that you could use to play
> notes on a nearby radio by tweaking some spinning loops. Quite a neat
> trick at the time since there wasn't any sound hardware.

Actually, this technique predates the PET by any years. I know that we
could play music on the PDP-1 and that goes back to the late '05s or
early 60's. I did it on my PDP-11 in the early '70s. I also heard a CDC
MASStore tape system played as an organ by adjusting the tape movement
in the vacuum columns.
-- 
R. Kevin Oberman, Network Engineer
Energy Sciences Network (ESnet)
Ernest O. Lawrence Berkeley National Laboratory (Berkeley Lab)
E-mail: oberman at es.net			Phone: +1 510 486-8634