diff --git a/Makefile.common b/Makefile.common
index f72e37c..fe710f6 100644
--- a/Makefile.common
+++ b/Makefile.common
@@ -35,6 +35,7 @@ SOURCES_C += \
 				 $(CORE_DIR)/misc.c \
 				 $(CORE_DIR)/fceu.c \
 				 $(CORE_DIR)/fds.c \
+				 $(CORE_DIR)/fds_apu.c \
 				 $(CORE_DIR)/file.c \
 				 $(CORE_DIR)/filter.c \
 				 $(CORE_DIR)/general.c \
diff --git a/src/boards/103.c b/src/boards/103.c
index 9d35e14..3f69a78 100644
--- a/src/boards/103.c
+++ b/src/boards/103.c
@@ -17,11 +17,12 @@
  * along with this program; if not, write to the Free Software
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
  *
- * FDS Conversion
+ * FDS Conversion - Doki Doki Panic
  *
  */
 
 #include "mapinc.h"
+#include "../fds_apu.h"
 
 static uint8 reg0, reg1, reg2;
 static uint8 *WRAM = NULL;
@@ -80,6 +81,7 @@ static DECLFW(M103Write2) {
 }
 
 static void M103Power(void) {
+	FDSSoundPower();
 	reg0 = reg1 = 0; reg2 = 0;
 	Sync();
 	SetReadHandler(0x6000, 0x7FFF, CartBR);
diff --git a/src/boards/353.c b/src/boards/353.c
index 63222b5..10a49a6 100644
--- a/src/boards/353.c
+++ b/src/boards/353.c
@@ -25,6 +25,7 @@
 
 #include "mapinc.h"
 #include "mmc3.h"
+#include "../fds_apu.h"
 
 static uint8* CHRRAM = NULL;
 static uint32 CHRRAMSIZE;
@@ -96,6 +97,7 @@ static DECLFW(M353Write) {
 }
 
 static void M353Power(void) {
+	FDSSoundPower();
 	EXPREGS[0] = 0;
 	GenMMC3Power();
 	SetWriteHandler(0x8000, 0xFFFF, M353Write);
@@ -104,6 +106,7 @@ static void M353Power(void) {
 static void M353Reset(void) {
 	EXPREGS[0] = 0;
 	MMC3RegReset();
+	FDSSoundReset();
 }
 
 static void M353Close(void) {
diff --git a/src/boards/359.c b/src/boards/359.c
index c1194b1..926302a 100644
--- a/src/boards/359.c
+++ b/src/boards/359.c
@@ -23,6 +23,7 @@
  */
 
 #include "mapinc.h"
+#include "../fds_apu.h"
 
 static uint32 mapperNum;
 static uint8 preg[4];
@@ -140,6 +141,7 @@ static DECLFW(M359WriteEx) {
 }
 
 static void M359Power(void) {
+	FDSSoundPower();
 	Sync();
 	SetReadHandler(0x6000, 0xFFFF, CartBR);
 	SetWriteHandler(0x8000, 0x8FFF, M359WritePRG);
@@ -148,6 +150,11 @@ static void M359Power(void) {
 	SetWriteHandler(0xC000, 0xCFFF, M359WriteIRQ);
 }
 
+static void M359Reset(void) {
+	FDSSoundReset();
+	Sync();
+}
+
 static void FP_FASTAPASS(1) M359CPUHook(int a) {
 	if (!irqPA12) {
 		if (IRQa && IRQCount16) {
@@ -177,6 +184,7 @@ static void StateRestore(int version) {
 void Mapper359_Init(CartInfo* info) {
 	mapperNum = 359;
 	info->Power = M359Power;
+	info->Reset = M359Reset;
 	MapIRQHook = M359CPUHook;
 	GameHBIRQHook = M359IRQHook;
 	GameStateRestore = StateRestore;
diff --git a/src/boards/42.c b/src/boards/42.c
index d012258..b507c34 100644
--- a/src/boards/42.c
+++ b/src/boards/42.c
@@ -23,6 +23,7 @@
  */
 
 #include "mapinc.h"
+#include "../fds_apu.h"
 
 static uint8 preg, creg, mirr;
 static uint32 IRQCount, IRQa;
@@ -54,6 +55,7 @@ static DECLFW(M42Write) {
 }
 
 static void M42Power(void) {
+	FDSSoundPower();
 	preg = 0;
 	mirr = 1;	/* Ai Senshi Nicol actually has fixed mirroring, but mapper forcing it's default value now */
 	Sync();
diff --git a/src/boards/539.c b/src/boards/539.c
index 8b1927e..e360aa5 100644
--- a/src/boards/539.c
+++ b/src/boards/539.c
@@ -18,7 +18,10 @@
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
  */
 
+/* FDS Conversion - Kid Icarus (パルテナの鏡) (Parthena) */
+
 #include "mapinc.h"
+#include "../fds_apu.h"
 
 static uint8 preg;
 static uint8 mirr;
@@ -82,6 +85,7 @@ static DECLFW(M539Write) {
 }
 
 static void M539Power(void) {
+	FDSSoundPower();
 	preg = 0;
 	mirr = 0;
 	Sync();
diff --git a/src/boards/KS7016.c b/src/boards/KS7016.c
index c7f5ff8..18c54d4 100644
--- a/src/boards/KS7016.c
+++ b/src/boards/KS7016.c
@@ -25,6 +25,7 @@
  */
 
 #include "mapinc.h"
+#include "../fds_apu.h"
 
 static uint8 preg;
 
@@ -68,6 +69,7 @@ static DECLFW(UNLKS7016Write) {
 }
 
 static void UNLKS7016Power(void) {
+	FDSSoundPower();
 	preg = 8;
 	Sync();
 	SetReadHandler(0x6000, 0xffff, CartBR);
diff --git a/src/boards/KS7017.c b/src/boards/KS7017.c
index b1c9d87..1e4a830 100644
--- a/src/boards/KS7017.c
+++ b/src/boards/KS7017.c
@@ -17,11 +17,12 @@
  * along with this program; if not, write to the Free Software
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
  *
- * FDS Conversion
+ * FDS Conversion - Almana No Kiseki
  *
  */
 
 #include "mapinc.h"
+#include "../fds_apu.h"
 
 static uint8 latche, reg, mirr;
 static int32 IRQa, IRQCount, IRQLatch;
@@ -52,19 +53,23 @@ static DECLFW(UNLKS7017Write) {
 	} else if ((A & 0xFF00) == 0x5100) {
 		reg = latche;
 		Sync();
-	} else if (A == 0x4020) {
-		X6502_IRQEnd(FCEU_IQEXT);
-		IRQCount &= 0xFF00;
-		IRQCount |= V;
-	} else if (A == 0x4021) {
-		X6502_IRQEnd(FCEU_IQEXT);
-		IRQCount &= 0xFF;
-		IRQCount |= V << 8;
-		IRQa = 1;
-	} else if (A == 0x4025) {
-		mirr = ((V & 8) >> 3) ^ 1;
+	} else {
+	 	if (A == 0x4020) {
+			X6502_IRQEnd(FCEU_IQEXT);
+			IRQCount &= 0xFF00;
+			IRQCount |= V;
+		} else if (A == 0x4021) {
+			X6502_IRQEnd(FCEU_IQEXT);
+			IRQCount &= 0xFF;
+			IRQCount |= V << 8;
+			IRQa = 1;
+		} else if (A == 0x4025) {
+			mirr = ((V & 8) >> 3) ^ 1;
+		}
+		FDSSoundWrite(A, V);
 	}
 }
+
 static DECLFR(FDSRead4030) {
 	X6502_IRQEnd(FCEU_IQEXT);
 	return X.IRQlow & FCEU_IQEXT ? 1 : 0;
@@ -81,6 +86,7 @@ static void FP_FASTAPASS(1) UNL7017IRQ(int a) {
 }
 
 static void UNLKS7017Power(void) {
+	FDSSoundPower();
 	Sync();
 	setchr8(0);
 	setprg8r(0x10, 0x6000, 0);
diff --git a/src/boards/KS7030.c b/src/boards/KS7030.c
index f9ece1f..fd758a5 100644
--- a/src/boards/KS7030.c
+++ b/src/boards/KS7030.c
@@ -17,7 +17,7 @@
  * along with this program; if not, write to the Free Software
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
  *
- * FDS Conversion
+ * FDS Conversion - Yume Koujou: Doki Doki Panic
  *
  * Logical bank layot 32 K BANK 0, 64K BANK 1, 32K ~0 hardwired, 8K is missing
  * need redump from MASKROM!
@@ -26,6 +26,7 @@
  */
 
 #include "mapinc.h"
+#include "../fds_apu.h"
 
 static uint8 reg0, reg1;
 static uint8 *WRAM = NULL;
@@ -108,6 +109,7 @@ static DECLFW(UNLKS7030Write1) {
 }
 
 static void UNLKS7030Power(void) {
+	FDSSoundPower();
 	reg0 = reg1 = ~0;
 	Sync();
 	SetReadHandler(0x6000, 0x7FFF, UNLKS7030RamRead0);
diff --git a/src/boards/KS7031.c b/src/boards/KS7031.c
index bbd1d84..4f961f4 100644
--- a/src/boards/KS7031.c
+++ b/src/boards/KS7031.c
@@ -17,11 +17,12 @@
  * along with this program; if not, write to the Free Software
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
  *
- * FDS Conversion
+ * FDS Conversion - dracula ii - noroi no fuuin [u][!]
  *
  */
 
 #include "mapinc.h"
+#include "fds_apu.h"
 
 static uint8 reg[4];
 
@@ -64,6 +65,7 @@ static DECLFW(UNLKS7031Write) {
 }
 
 static void UNLKS7031Power(void) {
+	FDSSoundPower();
 	Sync();
 	SetReadHandler(0x6000, 0xFFFF, CartBR);
 	SetWriteHandler(0x8000, 0xffff, UNLKS7031Write);
diff --git a/src/boards/KS7037.c b/src/boards/KS7037.c
index 17c047d..0c73c36 100644
--- a/src/boards/KS7037.c
+++ b/src/boards/KS7037.c
@@ -17,11 +17,12 @@
  * along with this program; if not, write to the Free Software
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
  *
- * FDS Conversion
+ * FDS Conversion - Metroid - Jin Ji Zhi Ling (Kaiser)(KS7037)[U][!]
  *
  */
 
 #include "mapinc.h"
+#include "../fds_apu.h"
 
 static uint8 reg[8], cmd;
 static uint8 *WRAM = NULL;
@@ -66,6 +67,7 @@ static DECLFW(UNLKS7037Write) {
 }
 
 static void UNLKS7037Power(void) {
+	FDSSoundPower();
 	reg[0] = reg[1] = reg[2] = reg[3] = reg[4] = reg[5] = reg[6] = reg[7] = 0;
 	WSync();
 	SetReadHandler(0x6000, 0xFFFF, CartBR);
diff --git a/src/boards/ac-08.c b/src/boards/ac-08.c
index 33bcc24..da26e39 100644
--- a/src/boards/ac-08.c
+++ b/src/boards/ac-08.c
@@ -24,6 +24,7 @@
  */
 
 #include "mapinc.h"
+#include "../fds_apu.h"
 
 static uint8 reg, mirr;
 static uint8 prg;
@@ -56,6 +57,7 @@ static DECLFW(AC08Write) {
 }
 
 static void AC08Power(void) {
+	FDSSoundPower();
 	reg = 0;
 	Sync();
 	SetReadHandler(0x6000, 0xFFFF, CartBR);
diff --git a/src/boards/datalatch.c b/src/boards/datalatch.c
index 1c6e577..46a3eee 100644
--- a/src/boards/datalatch.c
+++ b/src/boards/datalatch.c
@@ -20,6 +20,7 @@
 
 #include "mapinc.h"
 #include "../ines.h"
+#include "../fds_apu.h"
 
 static uint8 latche, latcheinit, bus_conflict;
 static uint16 addrreg0, addrreg1;
@@ -518,8 +519,14 @@ static void M538Sync(void) {
 	setmirror(1);
 }
 
+static void M538Power(void) {
+	FDSSoundPower();
+	LatchPower();
+}
+
 void Mapper538_Init(CartInfo *info) {
 	Latch_Init(info, M538Sync, 0, 0xC000, 0xCFFF, 1, 0);
+	info->Power = M538Power;
 }
 
 /* ------------------ A65AS --------------------------- */
diff --git a/src/boards/lh32.c b/src/boards/lh32.c
index 74a0a83..b0635a9 100644
--- a/src/boards/lh32.c
+++ b/src/boards/lh32.c
@@ -17,11 +17,12 @@
  * along with this program; if not, write to the Free Software
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
  *
- * FDS Conversion
+ * FDS Conversion - Monty no Doki Doki Daisassō, Monty on the Run, cartridge code LH32
  *
  */
 
 #include "mapinc.h"
+#include "../fds_apu.h"
 
 static uint8 reg;
 static uint8 *WRAM = NULL;
@@ -48,6 +49,7 @@ static DECLFW(LH32Write) {
 }
 
 static void LH32Power(void) {
+	FDSSoundPower();
 	Sync();
 	SetReadHandler(0x6000, 0xFFFF, CartBR);
 	SetWriteHandler(0xC000, 0xDFFF, CartBW);
diff --git a/src/boards/lh51.c b/src/boards/lh51.c
index 3236485..4a559bb 100644
--- a/src/boards/lh51.c
+++ b/src/boards/lh51.c
@@ -26,6 +26,7 @@
  */
 
 #include "mapinc.h"
+#include "../fds_apu.h"
 
 static uint8 reg, mirr;
 static uint8 *WRAM = NULL;
@@ -56,6 +57,7 @@ static DECLFW(LH51Write) {
 }
 
 static void LH51Power(void) {
+	FDSSoundPower();
 	Sync();
 	SetReadHandler(0x6000, 0xFFFF, CartBR);
 	SetWriteHandler(0x6000, 0x7FFF, CartBW);
diff --git a/src/boards/lh53.c b/src/boards/lh53.c
index 10aae81..1ee1592 100644
--- a/src/boards/lh53.c
+++ b/src/boards/lh53.c
@@ -17,11 +17,12 @@
  * along with this program; if not, write to the Free Software
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
  *
- * FDS Conversion
+ * FDS Conversion - Nazo no Murasamejō
  *
  */
 
 #include "mapinc.h"
+#include "../fds_apu.h"
 
 static uint8 reg, IRQa;
 static int32 IRQCount;
@@ -75,6 +76,7 @@ static void FP_FASTAPASS(1) LH53IRQ(int a) {
 }
 
 static void LH53Power(void) {
+	FDSSoundPower();
 	Sync();
 	SetReadHandler(0x6000, 0xFFFF, CartBR);
 	SetWriteHandler(0xB800, 0xD7FF, LH53RamWrite);
diff --git a/src/drivers/libretro/griffin.c b/src/drivers/libretro/griffin.c
index 0647180..3158363 100644
--- a/src/drivers/libretro/griffin.c
+++ b/src/drivers/libretro/griffin.c
@@ -21,6 +21,7 @@
 #include "misc.c"
 #include "fceu.c"
 #include "fds.c"
+#include "fds_apu.c"
 #include "file.c"
 #include "filter.c"
 #include "general.c"
diff --git a/src/fds.c b/src/fds.c
index f7358ab..3501915 100644
--- a/src/fds.c
+++ b/src/fds.c
@@ -26,6 +26,7 @@
 #include "x6502.h"
 #include "fceu.h"
 #include "fds.h"
+#include "fds_apu.h"
 #include "sound.h"
 #include "general.h"
 #include "state.h"
@@ -106,8 +107,6 @@ static uint8  mapperFDS_diskaccess; /* disk needs to be accessed at least once b
 #define GET_FDS_DISK() (diskdata[InDisk][mapperFDS_blockstart + mapperFDS_diskaddr])
 #define FDS_DISK_INSERTED (InDisk != 255)
 
-uint32 lastDiskPtrRead, lastDiskPtrWrite;
-
 #define DC_INC    1
 #define BYTES_PER_SIDE 65500
 
@@ -139,15 +138,9 @@ static void FDSStateRestore(int version) {
 		}
 }
 
-void FDSSound(int a);
-void FDSSoundReset(void);
-void FDSSoundStateAdd(void);
-static void RenderSound(void);
-static void RenderSoundHQ(void);
-
 static void FDSInit(void) {
 	memset(FDSRegs, 0, sizeof(FDSRegs));
-	lastDiskPtrRead = lastDiskPtrWrite = writeskip = DiskPtr = DiskSeekIRQ = 0;
+	writeskip = DiskPtr = DiskSeekIRQ = 0;
 
 	setmirror(1);
 	setprg8(0xE000, 0);			/* BIOS */
@@ -255,7 +248,6 @@ static DECLFR(FDSRead4031) {
 	static uint8 z = 0;
 	if (InDisk != 255) {
 		z = diskdata[InDisk][DiskPtr];
-		lastDiskPtrRead = DiskPtr;
 		#ifdef FCEUDEF_DEBUGGER
 		if (!fceuindbg)
 		#endif
@@ -328,261 +320,6 @@ static DECLFR(FDSRead4033) {
 	return 0x80;		/* battery */
 }
 
-/* Begin FDS sound */
-
-#define FDSClock (1789772.7272727272727272 / 2)
-
-typedef struct {
-	int64 cycles;		/* Cycles per PCM sample */
-	int64 count;		/* Cycle counter */
-	int64 envcount;		/* Envelope cycle counter */
-	uint32 b19shiftreg60;
-	uint32 b24adder66;
-	uint32 b24latch68;
-	uint32 b17latch76;
-	int32 clockcount;	/* Counter to divide frequency by 8. */
-	uint8 b8shiftreg88;	/* Modulation register. */
-	uint8 amplitude[2];	/* Current amplitudes. */
-	uint8 speedo[2];
-	uint8 mwcount;
-	uint8 mwstart;
-	uint8 mwave[0x20];	/* Modulation waveform */
-	uint8 cwave[0x40];	/* Game-defined waveform(carrier) */
-	uint8 SPSG[0xB];
-} FDSSOUND;
-
-static FDSSOUND fdso;
-
-#define  SPSG  fdso.SPSG
-#define b19shiftreg60  fdso.b19shiftreg60
-#define b24adder66  fdso.b24adder66
-#define b24latch68  fdso.b24latch68
-#define b17latch76  fdso.b17latch76
-#define b8shiftreg88  fdso.b8shiftreg88
-#define clockcount  fdso.clockcount
-#define amplitude  fdso.amplitude
-#define speedo    fdso.speedo
-
-void FDSSoundStateAdd(void) {
-	AddExState(fdso.cwave, 64, 0, "WAVE");
-	AddExState(fdso.mwave, 32, 0, "MWAV");
-	AddExState(amplitude, 2, 0, "AMPL");
-	AddExState(SPSG, 0xB, 0, "SPSG");
-
-	AddExState(&b8shiftreg88, 1, 0, "B88");
-
-	AddExState(&clockcount, 4, 1, "CLOC");
-	AddExState(&b19shiftreg60, 4, 1, "B60");
-	AddExState(&b24adder66, 4, 1, "B66");
-	AddExState(&b24latch68, 4, 1, "B68");
-	AddExState(&b17latch76, 4, 1, "B76");
-}
-
-static DECLFR(FDSSRead) {
-	switch (A & 0xF) {
-	case 0x0: return(amplitude[0] | (X.DB & 0xC0));
-	case 0x2: return(amplitude[1] | (X.DB & 0xC0));
-	}
-	return(X.DB);
-}
-
-static DECLFW(FDSSWrite) {
-	if (FSettings.SndRate) {
-		if (FSettings.soundq >= 1)
-			RenderSoundHQ();
-		else
-			RenderSound();
-	}
-	A -= 0x4080;
-	switch (A) {
-	case 0x0:
-	case 0x4:
-		if (V & 0x80)
-			amplitude[(A & 0xF) >> 2] = V & 0x3F;
-		break;
-	case 0x7:
-		b17latch76 = 0;
-		SPSG[0x5] = 0;
-		break;
-	case 0x8:
-		b17latch76 = 0;
-		fdso.mwave[SPSG[0x5] & 0x1F] = V & 0x7;
-		SPSG[0x5] = (SPSG[0x5] + 1) & 0x1F;
-		break;
-	}
-	SPSG[A] = V;
-}
-
-/* $4080 - Fundamental wave amplitude data register 92
- * $4082 - Fundamental wave frequency data register 58
- * $4083 - Same as $4082($4083 is the upper 4 bits).
- *
- * $4084 - Modulation amplitude data register 78
- * $4086 - Modulation frequency data register 72
- * $4087 - Same as $4086($4087 is the upper 4 bits)
- */
-
-
-static void DoEnv() {
-	int x;
-
-	for (x = 0; x < 2; x++)
-		if (!(SPSG[x << 2] & 0x80) && !(SPSG[0x3] & 0x40)) {
-			static int counto[2] = { 0, 0 };
-
-			if (counto[x] <= 0) {
-				if (!(SPSG[x << 2] & 0x80)) {
-					if (SPSG[x << 2] & 0x40) {
-						if (amplitude[x] < 0x3F)
-							amplitude[x]++;
-					} else {
-						if (amplitude[x] > 0)
-							amplitude[x]--;
-					}
-				}
-				counto[x] = (SPSG[x << 2] & 0x3F);
-			} else
-				counto[x]--;
-		}
-}
-
-static DECLFR(FDSWaveRead) {
-	return(fdso.cwave[A & 0x3f] | (X.DB & 0xC0));
-}
-
-static DECLFW(FDSWaveWrite) {
-	if (SPSG[0x9] & 0x80)
-		fdso.cwave[A & 0x3f] = V & 0x3F;
-}
-
-static int ta;
-static INLINE void ClockRise(void) {
-	if (!clockcount) {
-		ta++;
-
-		b19shiftreg60 = (SPSG[0x2] | ((SPSG[0x3] & 0xF) << 8));
-		b17latch76 = (SPSG[0x6] | ((SPSG[0x07] & 0xF) << 8)) + b17latch76;
-
-		if (!(SPSG[0x7] & 0x80)) {
-			int t = fdso.mwave[(b17latch76 >> 13) & 0x1F] & 7;
-			int t2 = amplitude[1];
-			int adj = 0;
-
-			if ((t & 3)) {
-				if ((t & 4))
-					adj -= (t2 * ((4 - (t & 3))));
-				else
-					adj += (t2 * ((t & 3)));
-			}
-			adj *= 2;
-			if (adj > 0x7F) adj = 0x7F;
-			if (adj < -0x80) adj = -0x80;
-			b8shiftreg88 = 0x80 + adj;
-		} else {
-			b8shiftreg88 = 0x80;
-		}
-	} else {
-		b19shiftreg60 <<= 1;
-		b8shiftreg88 >>= 1;
-	}
-	b24adder66 = (b24latch68 + b19shiftreg60) & 0x1FFFFFF;
-}
-
-static INLINE void ClockFall(void) {
-	if ((b8shiftreg88 & 1))
-		b24latch68 = b24adder66;
-	clockcount = (clockcount + 1) & 7;
-}
-
-static INLINE int32 FDSDoSound(void) {
-	fdso.count += fdso.cycles;
-	if (fdso.count >= ((int64)1 << 40)) {
- dogk:
-		fdso.count -= (int64)1 << 40;
-		ClockRise();
-		ClockFall();
-		fdso.envcount--;
-		if (fdso.envcount <= 0) {
-			fdso.envcount += SPSG[0xA] * 3;
-			DoEnv();
-		}
-	}
-	if (fdso.count >= 32768) goto dogk;
-
-	/* Might need to emulate applying the amplitude to the waveform a bit better... */
-	{
-		int k = amplitude[0];
-		if (k > 0x20) k = 0x20;
-		return (fdso.cwave[b24latch68 >> 19] * k) * 4 / ((SPSG[0x9] & 0x3) + 2);
-	}
-}
-
-static int32 FBC = 0;
-
-static void RenderSound(void) {
-	int32 end, start;
-	int32 x;
-
-	start = FBC;
-	end = (SOUNDTS << 16) / soundtsinc;
-	if (end <= start)
-		return;
-	FBC = end;
-
-	if (!(SPSG[0x9] & 0x80))
-		for (x = start; x < end; x++) {
-			uint32 t = FDSDoSound();
-			t += t >> 1;
-			t >>= 4;
-			Wave[x >> 4] += t;	/* (t>>2)-(t>>3); */ /* >>3; */
-		}
-}
-
-static void RenderSoundHQ(void) {
-	uint32 x;
-
-	if (!(SPSG[0x9] & 0x80))
-		for (x = FBC; x < SOUNDTS; x++) {
-			uint32 t = FDSDoSound();
-			t += t >> 1;
-			WaveHi[x] += t;	/* (t<<2)-(t<<1); */
-		}
-	FBC = SOUNDTS;
-}
-
-static void HQSync(int32 ts) {
-	FBC = ts;
-}
-
-void FDSSound(int c) {
-	RenderSound();
-	FBC = c;
-}
-
-static void FDS_ESI(void) {
-	if (FSettings.SndRate) {
-		if (FSettings.soundq >= 1) {
-			fdso.cycles = (int64)1 << 39;
-		} else {
-			fdso.cycles = ((int64)1 << 40) * FDSClock;
-			fdso.cycles /= FSettings.SndRate * 16;
-		}
-	}
-	SetReadHandler(0x4040, 0x407f, FDSWaveRead);
-	SetWriteHandler(0x4040, 0x407f, FDSWaveWrite);
-	SetWriteHandler(0x4080, 0x408A, FDSSWrite);
-	SetReadHandler(0x4090, 0x4092, FDSSRead);
-}
-
-void FDSSoundReset(void) {
-	memset(&fdso, 0, sizeof(fdso));
-	FDS_ESI();
-	GameExpSound.HiSync = HQSync;
-	GameExpSound.HiFill = RenderSoundHQ;
-	GameExpSound.Fill = FDSSound;
-	GameExpSound.RChange = FDS_ESI;
-}
-
 static DECLFW(FDSWrite) {
 	switch (A) {
 	case 0x4020:
@@ -618,7 +355,6 @@ static DECLFW(FDSWrite) {
 				else if (DiskPtr >= 2) {
 					DiskWritten = 1;
 					diskdata[InDisk][DiskPtr - 2] = V;
-					lastDiskPtrWrite = DiskPtr - 2;
 				}
 			}
 		}
diff --git a/src/fds.h b/src/fds.h
index 236d936..47b6412 100644
--- a/src/fds.h
+++ b/src/fds.h
@@ -4,12 +4,8 @@
 uint8 *FDSROM_ptr(void);
 uint32 FDSROM_size(void);
 
-void FDSSoundReset(void);
-
 void FCEU_FDSInsert(int oride);
 void FCEU_FDSEject(void);
 void FCEU_FDSSelect(void);
 
-extern uint32 lastDiskPtrRead, lastDiskPtrWrite;
-
 #endif
diff --git a/src/fds_apu.c b/src/fds_apu.c
new file mode 100644
index 0000000..8d67d36
--- /dev/null
+++ b/src/fds_apu.c
@@ -0,0 +1,298 @@
+/* FCE Ultra - NES/Famicom Emulator
+ *
+ * Copyright notice for this file:
+ *  Copyright (C) 2002 Xodnizel
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ */
+
+/* Begin FDS sound */
+
+#include "fceu-types.h"
+#include "x6502.h"
+#include "fceu.h"
+#include "sound.h"
+
+#define FDSClock (1789772.7272727272727272 / 2)
+
+typedef struct {
+	int64 cycles;		/* Cycles per PCM sample */
+	int64 count;		/* Cycle counter */
+	int64 envcount;		/* Envelope cycle counter */
+	uint32 b19shiftreg60;
+	uint32 b24adder66;
+	uint32 b24latch68;
+	uint32 b17latch76;
+	int32 clockcount;	/* Counter to divide frequency by 8. */
+	uint8 b8shiftreg88;	/* Modulation register. */
+	uint8 amplitude[2];	/* Current amplitudes. */
+	uint8 speedo[2];
+	uint8 mwcount;
+	uint8 mwstart;
+	uint8 mwave[0x20];	/* Modulation waveform */
+	uint8 cwave[0x40];	/* Game-defined waveform(carrier) */
+	uint8 SPSG[0xB];
+} FDSSOUND;
+
+static FDSSOUND fdso;
+
+#define  SPSG  fdso.SPSG
+#define b19shiftreg60  fdso.b19shiftreg60
+#define b24adder66  fdso.b24adder66
+#define b24latch68  fdso.b24latch68
+#define b17latch76  fdso.b17latch76
+#define b8shiftreg88  fdso.b8shiftreg88
+#define clockcount  fdso.clockcount
+#define amplitude  fdso.amplitude
+#define speedo    fdso.speedo
+
+void FDSSoundStateAdd(void) {
+	AddExState(fdso.cwave, 64, 0, "WAVE");
+	AddExState(fdso.mwave, 32, 0, "MWAV");
+	AddExState(amplitude, 2, 0, "AMPL");
+	AddExState(SPSG, 0xB, 0, "SPSG");
+
+	AddExState(&b8shiftreg88, 1, 0, "B88");
+
+	AddExState(&clockcount, 4, 1, "CLOC");
+	AddExState(&b19shiftreg60, 4, 1, "B60");
+	AddExState(&b24adder66, 4, 1, "B66");
+	AddExState(&b24latch68, 4, 1, "B68");
+	AddExState(&b17latch76, 4, 1, "B76");
+}
+
+static DECLFR(FDSSRead) {
+	switch (A & 0xF) {
+	case 0x0: return(amplitude[0] | (X.DB & 0xC0));
+	case 0x2: return(amplitude[1] | (X.DB & 0xC0));
+	}
+	return(X.DB);
+}
+
+static void RenderSound(void);
+static void RenderSoundHQ(void);
+
+static DECLFW(FDSSWrite) {
+	if (FSettings.SndRate) {
+		if (FSettings.soundq >= 1)
+			RenderSoundHQ();
+		else
+			RenderSound();
+	}
+	A -= 0x4080;
+	switch (A) {
+	case 0x0:
+	case 0x4:
+		if (V & 0x80)
+			amplitude[(A & 0xF) >> 2] = V & 0x3F;
+		break;
+	case 0x7:
+		b17latch76 = 0;
+		SPSG[0x5] = 0;
+		break;
+	case 0x8:
+		b17latch76 = 0;
+		fdso.mwave[SPSG[0x5] & 0x1F] = V & 0x7;
+		SPSG[0x5] = (SPSG[0x5] + 1) & 0x1F;
+		break;
+	}
+	SPSG[A] = V;
+}
+
+/* $4080 - Fundamental wave amplitude data register 92
+ * $4082 - Fundamental wave frequency data register 58
+ * $4083 - Same as $4082($4083 is the upper 4 bits).
+ *
+ * $4084 - Modulation amplitude data register 78
+ * $4086 - Modulation frequency data register 72
+ * $4087 - Same as $4086($4087 is the upper 4 bits)
+ */
+
+
+static void DoEnv() {
+	int x;
+
+	for (x = 0; x < 2; x++)
+		if (!(SPSG[x << 2] & 0x80) && !(SPSG[0x3] & 0x40)) {
+			static int counto[2] = { 0, 0 };
+
+			if (counto[x] <= 0) {
+				if (!(SPSG[x << 2] & 0x80)) {
+					if (SPSG[x << 2] & 0x40) {
+						if (amplitude[x] < 0x3F)
+							amplitude[x]++;
+					} else {
+						if (amplitude[x] > 0)
+							amplitude[x]--;
+					}
+				}
+				counto[x] = (SPSG[x << 2] & 0x3F);
+			} else
+				counto[x]--;
+		}
+}
+
+static DECLFR(FDSWaveRead) {
+	return(fdso.cwave[A & 0x3f] | (X.DB & 0xC0));
+}
+
+static DECLFW(FDSWaveWrite) {
+	if (SPSG[0x9] & 0x80)
+		fdso.cwave[A & 0x3f] = V & 0x3F;
+}
+
+static int ta;
+static INLINE void ClockRise(void) {
+	if (!clockcount) {
+		ta++;
+
+		b19shiftreg60 = (SPSG[0x2] | ((SPSG[0x3] & 0xF) << 8));
+		b17latch76 = (SPSG[0x6] | ((SPSG[0x07] & 0xF) << 8)) + b17latch76;
+
+		if (!(SPSG[0x7] & 0x80)) {
+			int t = fdso.mwave[(b17latch76 >> 13) & 0x1F] & 7;
+			int t2 = amplitude[1];
+			int adj = 0;
+
+			if ((t & 3)) {
+				if ((t & 4))
+					adj -= (t2 * ((4 - (t & 3))));
+				else
+					adj += (t2 * ((t & 3)));
+			}
+			adj *= 2;
+			if (adj > 0x7F) adj = 0x7F;
+			if (adj < -0x80) adj = -0x80;
+			b8shiftreg88 = 0x80 + adj;
+		} else {
+			b8shiftreg88 = 0x80;
+		}
+	} else {
+		b19shiftreg60 <<= 1;
+		b8shiftreg88 >>= 1;
+	}
+	b24adder66 = (b24latch68 + b19shiftreg60) & 0x1FFFFFF;
+}
+
+static INLINE void ClockFall(void) {
+	if ((b8shiftreg88 & 1))
+		b24latch68 = b24adder66;
+	clockcount = (clockcount + 1) & 7;
+}
+
+static INLINE int32 FDSDoSound(void) {
+	fdso.count += fdso.cycles;
+	if (fdso.count >= ((int64)1 << 40)) {
+ dogk:
+		fdso.count -= (int64)1 << 40;
+		ClockRise();
+		ClockFall();
+		fdso.envcount--;
+		if (fdso.envcount <= 0) {
+			fdso.envcount += SPSG[0xA] * 3;
+			DoEnv();
+		}
+	}
+	if (fdso.count >= 32768) goto dogk;
+
+	/* Might need to emulate applying the amplitude to the waveform a bit better... */
+	{
+		int k = amplitude[0];
+		if (k > 0x20) k = 0x20;
+		return (fdso.cwave[b24latch68 >> 19] * k) * 4 / ((SPSG[0x9] & 0x3) + 2);
+	}
+}
+
+static int32 FBC = 0;
+
+static void RenderSound(void) {
+	int32 end, start;
+	int32 x;
+
+	start = FBC;
+	end = (SOUNDTS << 16) / soundtsinc;
+	if (end <= start)
+		return;
+	FBC = end;
+
+	if (!(SPSG[0x9] & 0x80))
+		for (x = start; x < end; x++) {
+			uint32 t = FDSDoSound();
+			t += t >> 1;
+			t >>= 4;
+			Wave[x >> 4] += t;	/* (t>>2)-(t>>3); */ /* >>3; */
+		}
+}
+
+static void RenderSoundHQ(void) {
+	uint32 x;
+
+	if (!(SPSG[0x9] & 0x80))
+		for (x = FBC; x < SOUNDTS; x++) {
+			uint32 t = FDSDoSound();
+			t += t >> 1;
+			WaveHi[x] += t;	/* (t<<2)-(t<<1); */
+		}
+	FBC = SOUNDTS;
+}
+
+static void HQSync(int32 ts) {
+	FBC = ts;
+}
+
+void FDSSound(int c) {
+	RenderSound();
+	FBC = c;
+}
+
+static void FDS_ESI(void) {
+	if (FSettings.SndRate) {
+		if (FSettings.soundq >= 1) {
+			fdso.cycles = (int64)1 << 39;
+		} else {
+			fdso.cycles = ((int64)1 << 40) * FDSClock;
+			fdso.cycles /= FSettings.SndRate * 16;
+		}
+	}
+	SetReadHandler(0x4040, 0x407f, FDSWaveRead);
+	SetWriteHandler(0x4040, 0x407f, FDSWaveWrite);
+	SetWriteHandler(0x4080, 0x408A, FDSSWrite);
+	SetReadHandler(0x4090, 0x4092, FDSSRead);
+}
+
+void FDSSoundReset(void) {
+	memset(&fdso, 0, sizeof(fdso));
+	FDS_ESI();
+	GameExpSound.HiSync = HQSync;
+	GameExpSound.HiFill = RenderSoundHQ;
+	GameExpSound.Fill = FDSSound;
+	GameExpSound.RChange = FDS_ESI;
+}
+
+DECLFR(FDSSoundRead) {
+	if (A >= 0x4040 && A < 0x4080) return FDSWaveRead(A);
+	if (A >= 0x4090 && A < 0x4093) return FDSSRead(A);
+	return X.DB;
+}
+
+DECLFW(FDSSoundWrite) {
+	if (A >= 0x4040 && A < 0x4080) FDSWaveWrite(A, V);
+	else if (A >= 0x4080 && A < 0x408B) FDSSWrite(A, V);
+}
+
+void FDSSoundPower(void) {
+	FDSSoundReset();
+	FDSSoundStateAdd();
+}
\ No newline at end of file
diff --git a/src/fds_apu.h b/src/fds_apu.h
new file mode 100644
index 0000000..0aac02c
--- /dev/null
+++ b/src/fds_apu.h
@@ -0,0 +1,12 @@
+#ifndef FDS_APU_H
+#define FDS_APU_H
+
+void FDSSoundReset(void);
+void FDSSoundStateAdd(void);
+
+/* Used for fds conversion-based mappers to allow access to fds apu registers */
+void FDSSoundPower(void); 
+DECLFR(FDSSoundRead);   /* $4040-$407F, $4090-$4092 */
+DECLFW(FDSSoundWrite);  /* $4040-$407F, $4080-$408A */
+
+#endif /* FDS_APU_H */
\ No newline at end of file
diff --git a/src/nsf.c b/src/nsf.c
index 38b385e..a18c694 100644
--- a/src/nsf.c
+++ b/src/nsf.c
@@ -33,6 +33,7 @@
 #include "fceu-memory.h"
 #include "file.h"
 #include "fds.h"
+#include "fds_apu.h"
 #include "cart.h"
 #include "input.h"