SamMaEl wrote:
> 	"Higher" frequency, lower pitch. Just like when you pluck a
> string, then shorten the string by a half, the note will sound an octave
> higher. Or, so said Pythagoras. And just the same, cutting the
> frequency in half raises the pitch an octave. So, 880 Hz would be the A
> above middle C, and 440 Hz would be the A an octave higher than the 880 A.

Ah.  I'm glad someone knows something about music and sound.  I've learned
quite a bit in the few months since I've started this, but I'm still
basically clueless :-)  Thanks for the explanation.

> 	Apple's "Simple Beep" is 880 == "A" above "middle C" I matched
> "beep" up against the "Simple Beep" that comes with MacOS, and besides the
> effects (the beep decays towards the end, whereas Colin's beep is a
> constant on then off) I found 880, xxx (I used 110), 15 came close to the
> sound of the Simple Beep. That is, if you LIKE the Simple Beep ;-)

It'll probably work well enough for me.  Unless there is a lot of
disagreement, that may be close to what I go with, although I might
shorten it some.
 
> 	And, it works just fine on my Q630, with standard sound hardware.
> I would try it with my speakers, but they're on my Q900 and I'm currently
> too lazy to unplug them and move them across the room ;-)

:-)

> 	How difficult would it be to get 16-bit sound working?

I'm not sure.  From a few traces through MacsBug, I think that the Sound
Manager currently does some kind of 16->8-bit conversion before playing
the converted 8-bit sample.  We may have to do the same.  PowerMac sound
hardware can do 16-bit, I think, however, and there might be some
similarities.  We'll have to see.

> Wouldn't it
> be nice to have your Mac boot into NetBSD and emit a lovely, stereo sound
> "Welcome to MacBSD" at boottime? ;-)

Well, that's tougher than it sounds :-)  The method that I'm currently
using requires that timeout() be available, and that's not available until
the end of autoconfig :-(  So, I think we might be out of luck on this
one.  Stereo sound should work, tho.  In my beep program, I'm only writing
to the left channel sound buffer (I think).  The other buffer starts at
0x400 and extends to 0x800 if you want to play with strange stereo tones.

> Seeing as Apple probably would be
> upset if someone stole their startup chime... But, who thinks that once
> sound is working decently it might be cool to experiment with a
> NetBSD/mac68k "startup chime"? ;-)

Oh, I'd love to get it, but I haven't found where it is quite yet.  I'm
assuming it's somewhere in ROM, but the startup routines get relocated, so
I haven't managed to find them quite yet.  Oh well.... :-)

Thanks for the feedback.

Later.

-- 
Colin Wood                                 cwood@ichips.intel.com
Component Design Engineer - PMD                 Intel Corporation
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I speak only on my own behalf, not for my employer.