Intel 810A3, Design Manual

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Intel
®
810A3 Chipset Design Guide 1-11
Introduction
1.3.3 AC’97
The Audio Codec ’97 (AC’97) Specification defines a digital link that can be used to attach an
audio codec (AC), a modem codec (MC), an audio/modem codec (AMC), or both an AC and an
MC. The AC’97 Specification defines the interface between the system logic and the audio or
modem codec known as the AC’97 Digital Link.
The ability to add cost-effective audio and modem solutions as the platform migrates away from
ISA is important. The AC’97 audio and modem components are software configurable, reducing
configuration errors. The Intel

810A3 chipset’s AC’97 (with the appropriate codecs) not only
replaces ISA audio and modem functionality, but also improves overall platform integration by
incorporating the AC’97 digital link. Using the Intel

810A3 chipset’s integrated AC’97 digital
link reduces cost and eases migration from ISA.
The ICH is an AC’97 compliant controller that supports up to two codecs with independent PCI
functions for audio and modem. The ICH communicates with the codec(s) via a digital serial link
called the AC-link. All digital audio/modem streams and command/status information is
communicated over the AC-link. Microphone input and left and right audio channels are supported
for a high quality two-speaker audio solution. Wake on ring from suspend is also supported with an
appropriate modem codec.
By using an audio codec, the AC’97 digital link allows for cost-effective, high-quality, integrated
audio on the Intel

810A3 chipset platform. In addition, an AC’97 soft modem can be
implemented with the use of a modem codec. Several system options exist when implementing
AC’97. The Intel

810A3 chipset’s integrated digital link allows two external codecs to be
connected to the ICH. The system designer can provide audio with an audio codec ( Figure 1-2 a) or
a modem with a modem codec ( Figure 1-2 b). For systems requiring both audio and a modem,
there are two solutions. The audio codec and the modem codec can be integrated into an AMC
(
Figure 1-2 c), or separate audio and modem codecs can be connected to the ICH ( Figure 1-2 d).
The modem implementation for different countries should be considered as telephone systems
vary. By using a split design, the audio codec can be on-board and the modem codec can be placed
on a riser. Intel is developing an AC’97 digital link connector. With a single integrated codec, or
AMC, both audio and modem can be routed to a connector near the rear panel where the external
ports can be located.