On 5 Sep 00, at 9:38, Demetri Kolokotronis wrote:

> Jim Meagher stated internal speaker and external speaker circuits
> are not related, but did not explain why, if this is so, I hear
> "system sounds" from external speakers.

  On every system that I have built or examined, the internal speaker
connects to a simple motherboard circuit driven off a channel of the
timer chip; by the time it was becoming common knowledge how to
produce decent sound with this arrangement, sound cards had come down
in price and made the matter moot.  The classic/standard internal
speaker is a fossil, a holdover from an earlier time.

  It is *possible* that a few systems, with sound card functionality
built in on the motherboard, make more advanced use of the speaker
built into the case, but these cases would be rare.  [As several
people pointed out, there was a Windows sound driver for the classic
speaker arrangement, but it was never supported or recommended.]

> Joe Cuffy stated, contrary to above, that plugging in external
> speakers transfers internal speaker input to external speakers.
> However, I do not hear "system sounds" from internal speaker with
> external speakers unplugged, indicating that plugging in external
> speakers does not affect internal speaker.

  This would not be the classic/standard arrangement, but it's just
possible that some machines might work this way; yours could be one
of them.

> No one has addressed whether the fact that mobo has four speaker
> connections, while internal speaker has two leads, leaving two
> mobo speaker connections unfilled, relates to lack of output from
> internal speaker.

  I don't think anyone knows *why* the speaker connector has two dead
pins between the two live ones -- except that the original IBM PC did
it that way.  Possibly it's to make sure that there's no way you can
put the speaker current through one of the case LEDs?
  In any case, the wiring you describe is totally classic/standard,
and so unlikely to be relevant to your specific problem.

> I suspect something is missing in internal speaker circuit, and
> that software has routed "system sounds" to external speaker.
> Hearing "system sounds" only through external speakers has the
> disadvantage that I do not hear "system sounds" when external
> speakers are not turned on.

  Windows uses the term "system sounds" to refer to synthesized
sounds, played through a sound driver (and sound card, unless the
speaker driver referred to above is installed) and associated with
various user interface events.
  People answering your question have been trying to distinguish
between synthesized sounds played through a driver, and the much
cruder sounds generated by manipulating the timer-chip channel to
which the internal speaker is connected -- spunds typically
associated with the BIOS or with DOS commands.
  When you say that you hear "system sounds" through the external
speakers, many experienced readers are likely to assume that you are
applying the Windows terminology, and that these are sounds never
normally produced by the internal speaker.

  SO:  Either your motherboard is something special (I don't think
you've ever said what it is...), or, more likely, everything is
vanilla and working exactly as intended -- and this just isn't quite
as you expected.

David G

                  Visit our website regularly for FAQs,
               articles, how-to's, tech tips and much more
                  http://nospin.com - http://nospin.org