dos-man 64 said:
No, I don't get a beep at startup. I'm going to check the CMOS to see
if there is any type of option to shut it off. It doesn't look good.
As a last chance resort, I'll see if I can whip up a TSR to beep the
sound card instead. Sounds like fun
The computer case speaker doesn't come from the sound card.
Download a copy of 25281202 from this page. This is a reference
schematic for an 875 board (S478,DDR,AGP) motherboard.
http://www.intel.com/design/chipsets/schematics/252812.htm
First, go to PDF page 74. There, you'll find a case speaker
driver circuit. It uses a single transistor in emitter follower
mode. (I've seen other circuit implementations for the speaker
driver, so that isn't the only one.)
Then, head over to PDF page 34. The SPKR signal comes from ICH5,
the Southbridge on that motherboard.
Note that, on at least one board, when the "USB detect" function
had a beep sound added in the BIOS, it drove people bonkers.
There were people thinking the added sound meant their motherboard
was busted. The BIOS mod people, in a bid to quickly stop the
madness, disabled the SPKR drive completely at the BIOS level.
Whether that technique also causes plug and play enumeration
to ignore it as well, I don't know. If the BIOS people had
source, they could have removed the beep references in the
USB module, but apparently they didn't have access to that,
so they shut off beeps entirely. But that was only
done on a limited few board models, until the BIOS
geniuses at Award or AMI were told to stop doing it.
If two USB devices were detected at POST, users reported
hearing two "boop" sounds (as the sound created wasn't
at the same frequency as beep error codes).
Presumably, the SPKR output on the Southbridge, is tied to
the timer structure in the Southbridge, so that a timer can
be used to create the tone.
I understand that other devices on the motherboard can be
used for the "PC speaker" function, but on that Intel
reference schematic, they're using a pin labeled as such
on the Southbridge.
Paul