The sound circuitry in the iMac computer is called Tumbler. The Tumbler circuitry exchanges audio data with the Pangea IC over a standard I2S bus and receives commands from the Pangea IC over an I2C bus. The Pangea IC provides DB-DMA (descriptor-based direct memory access) support for the I2S bus.
The Tumbler sound circuitry includes a signal processing IC for equalization and volume control functions and a codec IC for A/D and D/A conversion.
The Tumbler circuitry performs analog-to-digital conversion for the internal microphone. Tumbler also performs digital-to-analog conversion for the audio signals it sends to the internal speaker and the headphone jack. A switch-mode power amplifier drives the internal speaker and the Apple Speaker minijack.
For a description of the features of the sound system, see "Sound System".