diff --git a/src/emu/sound/asc.c b/src/emu/sound/asc.c
index c5233c4f559..71047ca9270 100644
--- a/src/emu/sound/asc.c
+++ b/src/emu/sound/asc.c
@@ -372,6 +372,11 @@ READ8_MEMBER( asc_device::read )
 		m_regs[0x2f] = m_incr[3];
 	}
 
+	if (offset > 0x800)
+	{
+		return 0xff;
+	}
+
 	return m_regs[offset-0x800];
 }
 
@@ -582,6 +587,9 @@ WRITE8_MEMBER( asc_device::write )
 				break;
 		}
 
-		m_regs[offset-0x800] = data;
+		if (offset < 0x800)
+		{
+			m_regs[offset-0x800] = data;
+		}
 	}
 }
diff --git a/src/emu/sound/scsp.c b/src/emu/sound/scsp.c
index 6fd4ab901b0..e8ffe42dbda 100644
--- a/src/emu/sound/scsp.c
+++ b/src/emu/sound/scsp.c
@@ -982,8 +982,10 @@ static void SCSP_w16(scsp_state *scsp,address_space &space,unsigned int addr,uns
 		//DSP
 		if(addr<0x780)  //COEF
 			*((unsigned short *) (scsp->DSP.COEF+(addr-0x700)/2))=val;
-		else if(addr<0x800)
+		else if(addr<0x7c0)
 			*((unsigned short *) (scsp->DSP.MADRS+(addr-0x780)/2))=val;
+		else if(addr<0x800)	// MADRS is mirrored twice
+			*((unsigned short *) (scsp->DSP.MADRS+(addr-0x7c0)/2))=val;
 		else if(addr<0xC00)
 		{
 			*((unsigned short *) (scsp->DSP.MPRO+(addr-0x800)/2))=val;
@@ -1022,8 +1024,10 @@ static unsigned short SCSP_r16(scsp_state *scsp, address_space &space, unsigned
 		//DSP
 		if(addr<0x780)  //COEF
 			v= *((unsigned short *) (scsp->DSP.COEF+(addr-0x700)/2));
-		else if(addr<0x800)
+		else if(addr<0x7c0)
 			v= *((unsigned short *) (scsp->DSP.MADRS+(addr-0x780)/2));
+		else if(addr<0x800)
+			v= *((unsigned short *) (scsp->DSP.MADRS+(addr-0x7c0)/2));
 		else if(addr<0xC00)
 			v= *((unsigned short *) (scsp->DSP.MPRO+(addr-0x800)/2));
 		else if(addr<0xE00)