Is AC97 modem controller really a modem????

All modern PC motherboards have an on-board modem controller in their
specification. However, all those motherboards have just a modem audio
connector. I cannot find any RJ-?? style phone jacks.

Does it have really a modem?
AC97 modem always goes with a AC97 audio. All those motherboards
have three stereo audio jacks with something like i810 audio or
Cirrus audio. Then what is meant by AC97 audio? Is it separate from
i810 for example?

Thanks.

Hugh

On Sun, 31 Aug 2003 15:02:53 +0000, ghsong wrote:
All modern PC motherboards have an on-board modem controller in their
specification. However, all those motherboards have just a modem audio
connector. I cannot find any RJ-?? style phone jacks.

Does it have really a modem?

Nope. You need an add-in card, typically using one of those funky
little CNR or AMR slots. The add-in cards are dirt-cheap, though
these days a PCI software modem is also dirt-cheap. This sort of
thing can be built right into the motherboard, but there just isn't
much in the way of demand for this except with laptops.

AC97 modem always goes with a AC97 audio. All those motherboards
have three stereo audio jacks with something like i810 audio or
Cirrus audio. Then what is meant by AC97 audio? Is it separate from
i810 for example?

Intel's i810 chipset was, to the best of my knowledge, the first
chipset to support AC97 audio. By virtue of being the first, the two
are occasionally used somewhat interchangeably, though AC97 is
definitely the correct term here.

As for the Cirrus audio, that could be either related or another can
of worms altogether. See, AC97 audio, like the modem above, is not a
complete solution all on it's own. It needs an extra chip, a codec
(coder/decoder) in order to take the digital signal from the AC97
controller and convert it to an analog signal (and the reverse for
recording sound). These codec chips for sound are typically soldered
on the motherboard, somewhere near the back and then the analog front
end is connected to the three audio jacks you see at the back. The
modem portion of AC97 also needs a codec, but as mentioned above, this
is typically not included on desktop motherboards.

So where does Cirrus fit into this? Well Cirrus is one of many
companies that produces AC97 compatible codec chips. Analog Devices
and Realtek are the two biggest suppliers of such chips, but there are
a number of others. However, just using a Cirrus codec would still
give you AC97 audio, not "Cirrus" audio. Alternatively you could
include a full PCI sound card integrated right into the motherboard
(same idea as plugging a PCI card into a slot, only skipping the slot
part of it). Cirrus makes a sound chipset that can be used in such a
fashion, and I believe I have seen the odd motherboard with such
"Cirrus" sound integrated onto it.

Hope that helps clear a thing or two up.

-------------
Tony Hill
hilla underscore 20 at yahoo dot ca

On Sun, 31 Aug 2003 21:55:04 GMT, Tony Hill
put finger to keyboard and composed:

On Sun, 31 Aug 2003 15:02:53 +0000, ghsong wrote:
All modern PC motherboards have an on-board modem controller in their
specification. However, all those motherboards have just a modem audio
connector. I cannot find any RJ-?? style phone jacks.

Does it have really a modem?

Nope. You need an add-in card, typically using one of those funky
little CNR or AMR slots. The add-in cards are dirt-cheap, though
these days a PCI software modem is also dirt-cheap. This sort of
thing can be built right into the motherboard, but there just isn't
much in the way of demand for this except with laptops.

The reason I have seen quoted for non-inclusion of these DAAs is that
each motherboard model with an included DAA would need to be certified
by each country's telecoms authority. A separate universal DAA avoids
this requirement.


- Franc Zabkar
--
Please remove one 's' from my address when replying by email.