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Technical Reference Guide
Compaq Deskpro EXS and Workstation 300 Personal Computers
Featuring the Intel Pentium 4 Processor
First Edition - December 2000
5-31
5.8.5 AUDIO PROGRAMMING
Audio subsystem programming consists configuration, typically accomplished during POST, and
control, which occurs during runtime.
5.8.5.1 Audio Configuration
The audio subsystem is configured according to PCI protocol through the ES1373 audio controller.
Table 5-21 lists the PCI configuration registers of the audio subsystem.
Table 5–21. AC’97 Audio Controller PCI Configuration Registers
Table 5-21.
AC’97 Audio Controller
PCI Configuration Registers
PCI
Conf.
Addr. Register
Value
on
Reset
PCI
Conf.
Addr. Register
Value
on
Reset
00-01h Vender ID 1274h 14-17h Native Audio Bus Mstr. Addr. 0’s
02-03h Device ID 1373h 18-1Bh Reserved 0’s
04-05h PCI Command 0000h 1C-2Bh Reserved 0’s
06-07h PCI Status X610h 2C-2Dh Subsystem Vender ID 1274h
08h Revision ID 00h 2E-2Fh Subsystem ID 1373h
09h Programming 00h 30h Exp. ROM Addr. 0’s
0Ah Sub-Class 01h 34h Capabilities Pointer DCh
0Bh Base Class Code 04h 3Ch Interrupt Line xxh
0Eh Header Type 00h 3Dh Interrupt Pin 01h
10-13h Native Audio Mixer Base Addr. 1 3E, 3Fh Min. GNT/Min, LAT 800Ch
5.8.5.2 Audio Control
The audio subsystem is controlled through a set of indexed registers that physically reside in the
audio codec . The register addresses are decoded by the audio controller and forwarded to the
audio codec over the AC97 Link Bus previously described. The audio codec’s control registers
(Table 5-22) are mapped into 64 kilobytes of variable I/O space.
Table 5–22. AC’97 Audio Codec Control Registers
Table 5-22.
AC’97 Audio Codec Control Registers
Offset
Addr. / Register
Value
On
Reset
Offset
Addr. / Register
Value
On
Reset
Offset
Addr. / Register
Value
On
Reset
00h Reset 0100h 14h Video Vol. 8808h 28h Ext. Audio ID. 0001h
02h Master Vol. 8000h 16h Aux Vol. 8808h 2Ah Ext. Audio Ctrl/Sts 0000h
04h Reserved X 18h PCM Out Vol. 8808h 2Ch PCM DAC SRate BB80h
06h Mono Mstr. Vol. 8000h 1Ah Record Sel. 0000h 32h PCM ADC SRate BB80h
08h Reserved X 1Ch Record Gain 8000h 5Eh AC Mode Control 0080h
0Ah PC Beep Vol. 8000h 1Eh Reserved X 60h Misc. Cystal Cntrl. 0023h
0Ch Phone In Vol. 8008h 20h Gen. Purpose 0000h 68h S/PDIF Cntrl. 0000h
0Eh Mic Vol. 8008h 22h 3D Control 0000h -- --
10h Line In Vol. 8808h 24h Reserved X 7Ch Vender ID1 4352h
12h CD Vol. 8808h 26h Pwr Mgnt. 000xh 7Eh Vender ID2 5931h