Audio Codec '97

AC ‘97 Component Specification Revision 2.3 Rev 1.0
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(5) +3 dB output into 32 Ω load
(6) ±0.25 dB limits
(7) Stop Band rejection determines filter requirements. Out-of-Band rejection determines audible noise.
(8) The integrated Out-of-Band noise generated by the DAC process, during normal PCM audio playback,
over a bandwidth of 28.8 to 100 kHz, with respect to a 1VRMS DAC output.
(9) Gain step size 1.5 dB is true for all attenuators except for PC_BEEP, which has 3.0 dB step size.
Appendix A. AC ‘97 Register Set Summary
The AC ‘97 Register space supports 64 16-bit registers using even 7-bit addresses.
• Registers 00h – 26h are dedicated to the baseline audio feature set
• Registers 28h – 3Ah are dedicated to the extended audio feature set
• Registers 3Ch – 58h are dedicated to the standardized modem feature set
• Registers 5Ah – 7Ah are reserved for vendor-specific functionality
• Registers 7Ch and 7Eh are dedicated to Microsoft Plug and Play Vendor ID** (3 bytes) and vendor specific
device ID (8-bits)
All reserved bits (marked x) should be read as zero, and zeros should be written to these bits by Controllers and
software. All AC ‘97 Codecs should respond with 0 to accesses of odd-numbered registers instead of aliasing them
to the next lower even-numbered register. As a result, odd-numbered registers can be reserved for future expansion.