Learn More About AC97

Before the Intel High Definition (HD) Audio was introduced to us in 2004, an audio codec named AC97 was used.  This codec provided standardized features that developers needed to do when developing integrated PC audio devices.  The AC97 codec delivered high-quality computer sound devices capable of 45KHz/20bit playback in multichannel mode and 96KHz/20bit stereo playback.  Addressing I/O standards for modems with modem codec (MC87) along with combined modem /audio codec (AMC97) was also another feature of AC97 codec.

A long list of features were standard in this product such as:  16 bit full-duplex stereo audio, 48-pin QFP package pinout assignments, 1 to 2 analog mono inputs, 1 to 4 analog stereo inputs, MIC input with programmable gain, 20 Db boost, and AEC comparing capabilities, quality stereo output, auxiliary stereo output, high quality analog CD input, mono output for speaker phones, internal mono speaker output, and comprehensive Power Management.

Features that can be available if you so choose on the AC97 are:  18 to 20 bit DAC and ADC resolutions, tone and volume controls, 3D stereo enhancements, 3rd ADC input channel for dedicated voice input, digital output using an Integrated Sony/Philips Digital Interface transmitter, headphone output, Codec Interruption generation, Jack sensing, and reporting capabilities.

As far as connecting the AC97 digital controller, to the AC97 codec, it is connected by a digital link called the AC-Link.  This contained five wires, bi-directional TDM format that supported up to four CODEC’s on one circuit board.

AC97 was designed to support outputs like analog stereo, amplified stereo, headphones, analog 6-channel for front and surround sound PC speaker systems, analog matrix-encoded surround sound and digital 5.1 channel, for home theatre equipment.

The AC97 codec’s main functions are power management, clocking, signals, pin assignments, addressing, strapping, protocol, sample rates, behavior, slot assignments, performance characteristics, and many others.  However, the AC97 codec does not cover the AC97 Digital Controller alone.  Drivers are provided by the controllers manufacturers that go along with the AC97 standards.

Today we use our computers as home entertainment centers.  This home network system with multi channel audio and six to eight speaker was too powerful to use with the AC97.  Before when just watching a movie with stereo sound or listening to music was common usage, this product delivered exactly what it needed to.  Replaced with Intel’s HD Audio, users can do all that is need to get the best out of their “home entertainment media center.