cs4239 Cirrus Logic, Inc., cs4239 Datasheet - Page 55

• Manufacturer Part Number: cs4239
• Description: Crystalclear? Ortable Isa Audio System Logic
• Manufacturer: Cirrus Logic, Inc.

Reset
SBbase+6, write only
When bit D[0] of this register is set to a one and
then set to a zero, a reset of the Sound Blaster
interface will occur.
Read Data Port
SBbase+A, read only
When bit D[7] of the Data Available Register,
SBbase+E, is set =1 then valid data is available
in this register. The data may be the result of a
Command that was previously written to the
Command/Write Data Register or digital audio
data.
Command/Write Data
SBbase+C, write only
The Command/Write Data register is used to
send Sound Blaster Pro commands.
Write Buffer Status,
SBbase+C, read only
The Write Buffer Status register bit D[7] indi-
cates when the SBPro interface is ready to
DS253PP2
Register
0AH
0CH
0EH
2AH
2CH
2EH
00H
02H
04H
06H
08H
20H
22H
24H
26H
28H
D7
X
X
X
MASTER VOLUME LEFT
VOICE VOLUME LEFT
LINE VOLUME LEFT
FM VOLUME LEFT
CD VOLUME LEFT
D6
X
X
X
Table 15. SBPro Compatible Mixer Interface
D5
X
X
D4
X
X
X
DATA RESET
RESERVED
RESERVED
RESERVED
RESERVED
RESERVED
RESERVED
RESERVED
accept another command to the Command/Write
Data register. D[7]=1 indicates ready. D[7]=0 in-
dicates not ready.
Sound Blaster Mixer Registers
The Sound Blaster mixer registers are shown in
Table 15.
Reset Register,
Mixer Index 00H
Writing any value to this register will reset the
mixer to default values.
Voice Volume Register,
Mixer Index 04H, Default = 99H
This register provides 8 steps of voice volume
control each for the right and left channels.
Microphone Mixing Register,
Mixer Index 0AH, Default = 01H
This register provides 4 steps of microphone vol-
ume control.
D3
CrystalClear Portable ISA Audio System
X
X
MASTER VOLUME RIGHT
VOICE VOLUME RIGHT
LINE VOLUME RIGHT
FM VOLUME RIGHT
CD VOLUME RIGHT
INPUT SELECT
D2
X
TM
MIC MIXING
VSTC
D1
CS4239
D0
X
X
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