82801CA Datasheet, PDF (217/521 Pages) Intel Corporation – I/O Controller Hub 3-S (ICH3-S)

Functional Description
5.18.1.3
5.18.1.4
5.18.1.5
5.18.1.6
5.18.1.7
5.18.1.8
Output Slot 1: Command Address Port
The command port is used to control features and monitor status of AC ’97 functions including, but
not limited to, mixer settings and power management.
The control interface architecture supports up to 64 16-bit read/write registers, addressable on even
byte boundaries. Only the even registers (00h, 02h, etc.) are valid.
Output frame slot 1 communicates control register address, and Write/Read command information.
In the case of the split codec implementation, accesses to the codecs are differentiated by the driver
using address offsets 00h–7Fh for the primary codec and address offsets 80h–FEh for the secondary
codec. The differentiation on the link, however, is done via the codec ID bits. See Section 5.18.1.23
for further details.
Output Slot 2: Command Data Port
The command data port is used to deliver 16-bit control register write data in the event that the
current command port operation is a write cycle as indicated in slot 1, bit 19. If the current
command port operation is a read then the entire slot time stuffed with 0s by the ICH3. Bits [19:4]
contain the write data. Bits [3:0] are reserved and are stuffed with zeros.
Output Slot 3: PCM Playback Left Channel
Output frame slot 3 is the composite digital audio left playback stream. Typically this slot is
composed of standard PCM (.wav) output samples digitally mixed by the host processor. The ICH3
transmits sample streams of 16 bits and stuffs the remaining bits with zeros.
Data in output slots 3 and 4 from the ICH3 should be duplicated by software if there is only a single
channel out.
Output Slot 4: PCM Playback Right Channel
Output frame slot 4 is the composite digital audio right playback stream. Typically this slot is
composed of standard PCM (.wav) output samples digitally mixed by the host processor. The ICH3
transmits sample streams of 16 bits and stuffs the remaining bits with zeros.
Data in output slots 3 and 4 from the ICH3 should be duplicated by software if there is only a single
channel out.
Output Slot 5: Modem Codec
Output frame slot 5 contains modem DAC data. The modem DAC output supports 16-bit
resolution. At boot time, if the modem codec is supported, the AC ’97 controller driver determines
the DAC resolution. During normal runtime operation the ICH3 stuffs trailing bit positions within
this time slot with zeros.
Output Slot 6: PCM Playback Center Front Channel
When set up for 6 channel mode, this slot is used for the front center channel. The format is the
same as Slots 3. If not set up for 6 channel mode, this channel will always be stuffed with 0s by
ICH3.
Intel^® 82801CA ICH3-S Datasheet
217