Yamaha YMF724F specifications Sound Blaster Pro Mixer

YMF724F

2-2-2. Sound Blaster Pro Mixer

The following shows the register map of the Mixer section of Sound Blaster Pro.

Address	b7	b6	b5	b4	b3		b2		b1	b0	Remark
00h				Reset
04h	Voice Volume L			"1"	Voice Volume R					"1"
0Ah	-	-	-	"1"	-			MIC Volume*
0Ch	-	-	Ifilter*	"1"		Input Source*				"1"
0Eh	-	-	Ofilter*	"1"	-		-		St. SW	"1"	SB Pro Mixer
22h	Master Volume L			"1"	Master Volume R					"1"
26h	MIDI Volume L			"1"		MIDI Volume R				"1"
28h	CD Volume L*			"1"		CD Volume R*				"1"
2Eh	Line Volume L*			"1"		Line Volume R*				"1"
F0h	SBPDA	-	-	-	SS		SM		SE	SBPDR	Suspend / Resume
F1h				SCAN	DATA
F8h	-	-	-	-	-		-		-	SBI	IRQ Status

The registers marked with * exist, but do not function.

DS-1 does not have the circuit that corresponds to the SB Mixer. Therefore, the volume settings on the SB Mixer are converted to the DSP coefficients of DS-1 or to AC-2 register values.

The conversion for each case is described below.

(1) SB Mixer ® DSP

The volume of master, MIDI and Voice, are applied to this case.

When the SB register is set, a 14-bit coefficient value is determined from the following conversion table and used as the DSP coefficient. The attenuation value of Master Volume, MIDI, and voice are summed together to obtain the coefficient.

These volumes cannot be controlled from PCI Audio block.

September 21, 1998

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