Table D-4. Extended Modea; Table D-5. Fm Synthesizerc - Compaq Deskpro EP 6233 Technical Reference Manual

Appendix D Audio Card
The Extended Mode registers are listed in Table D-4. Like the compatibility registers listed
previously, these registers are accessed by writing the index value to I/O port 2n4h and reading
the value from or writing the value to I/O port 2n5h. Extended mode offers better performance by
providing more precise (higher bit resolution) control of audio levels and more control of audio
processing.
Table D–4. Extended Mode Audio Mixer Control Register Mapping
Index Function
14h Voice Volume
1Ah Mic Volume
1Ch ADC (recording) Source
1Eh Stereo/Mono Switch
32h Master Volume
36h FM Volume
38h CD Volume
3Eh Line Volume
NOTE: Refer to OEM's ES1868 data sheet for detailed registers descriptions.
D.3.2.2 FM Synthesis Control
The FM synthesis logic is typically mapped at 388h-38Bh. A total of 243 registers in two banks
are available. Accessing the registers is accomplished by first writing the index to register 388h
(for bank 0) or 38Ah (for bank 1) followed by writing the data to either 389h or 38Bh (for bank 0
or bank 1 respectively). If a succeeding data byte is destined for the same location then the
address need not be re-written. Location 388h can be read for FM synthesizer status. Table D-5
lists the FM synthsizer control registers.
Table D–5. FM Synthesizer Control Register Mapping
Index Bank 0 Function
01h Test - all 0s
02h Timer 1
03h Timer 2
04h Timer Mask/Timer Start
05h Not Used
08h Key Scale (KSR) # Determiner
20-35h AM, Vib, EG Type, KSR, Mult.
40-55h Key Scale Level, Tone Level
60-75h Attack Rate, Decay Rate
80-95h Sustain Level, Release Rate
A0-A8h Frequency Number
B0-B8h Key On, Block Octave, Frequency No.
BDh Depth of Block Octave, Frequency No.
C0-C8h Stereo Left/Right, Feedback, Connection
E0-F5h Wave Select
NOTE: Refer to OEM's ES1868 data sheet for detailed registers descriptions.
Abbreviations:
AM Amplitude Modulation (tremolo)
Vib Vibrato
D-10 Compaq Personal Computers
Table D-4.
Extended Mode Audio Mixer Control Register Mapping
Table D-5.
FM Synthesizer Control Register Mapping
Original - February 1998
Index Function
60, 62h Master Volume (Left, Right)
64h Master Volume Control
66h Volume Int. Req. Clear
74h DMA Transfer( 2
76h DMA Transfer (2
nd
78h 2 DMA Control 1
nd
7Ah 2 DMA Control 2
7Eh Test Register
Bank 1 Function
Test - all 0s
Not Used
Not Used
4-Operator Configure
4-Operator Enable
Not Used
Same as bank 0
Same as bank 0
Same as bank 0
Same as bank 0
Same as bank 0
Same as bank 0
Not Used
Same as bank 0
Same as bank 0
nd
) Count Reload (Low)
nd
) Count Reload (Hi)