AC '97 - technical definition

See AC'97.

(Audio Codec'97) A specification for building audio and modem functions on a PC motherboard. Introduced in 1996 by Intel, AC'97 provides 20-bit, 48 kHz audio with six channels (5.1). It supports one audio stream per system and a two element array microphone.

Controller and Codec
AC'97 is made up of a controller connected to analog/digital codecs by a 5-wire TDM interface called "AC Link." The two subsystems separate the digital controller, which is built into the PC chipset, from the analog circuits, which can be in a chip on the motherboard, a riser card or cabled close to the I/O connectors.

For international certification (homologation), modem codecs are often placed on riser cards, which can be easily interchanged. See HD Audio and riser card.