diff --git a/src/sound/ym2149.sv b/src/sound/ym2149.sv
index 4281952..1aa73ff 100644
--- a/src/sound/ym2149.sv
+++ b/src/sound/ym2149.sv
@@ -38,14 +38,6 @@
 //   1   0   write value
 //   1   1   set address
 //
-// Registers description
-// R0, R1, R2, R4, R4, R5 - Tone Generator Control
-// R6                     - Noise Generator Control
-// R7                     - Mixer Control-I/O Enable
-// R10, R11, R12          - Amplitude Control
-// R13, R14, R15          - Envelope Generator Control
-//	R13, R14               - Envelope Period Control
-// R15                    - Envelope Shape/Cycle Control
 
 module ym2149
 (
@@ -72,42 +64,39 @@ module ym2149
 	output [7:0] IOB_out
 );
 
-assign ACTIVE = ~ymreg[7][5:0];
+assign ACTIVE  = ~ymreg[7][5:0];
+assign IOA_out = ymreg[14];
+assign IOB_out = ymreg[15];
 
-assign     IOA_out = ymreg[14];
-assign     IOB_out = ymreg[15];
+reg [7:0] addr;
+reg [7:0] ymreg[16];
 
-reg        ena_div;
-reg        ena_div_noise;
-reg [7:0]  addr;
-reg [7:0]  ymreg[16];
-reg        env_ena;
-reg [4:0]  env_vol;
+// Write to PSG
+reg env_reset;
+always @(posedge CLK) begin
+	if(RESET) begin
+		ymreg     <= '{default:0};
+		ymreg[7]  <= '1;
+		addr      <= '0;
+		env_reset <= 0;
+	end else begin
+		env_reset <= 0;
+		if(BDIR) begin
+			if(BC) addr <= DI;
+			else if(!addr[7:4]) begin
+				ymreg[addr[3:0]] <= DI;
+				env_reset <= (addr == 13);
+			end
+		end
+	end
+end
 
-wire [7:0] volTableAy[16] = 
-       '{8'h00, 8'h03, 8'h04, 8'h06, 
-		   8'h0a, 8'h0f, 8'h15, 8'h22, 
-		   8'h28, 8'h41, 8'h5b, 8'h72, 
-		   8'h90, 8'hb5, 8'hd7, 8'hff
-		 };
-
-wire [7:0] volTableYm[32] = 
-		'{8'h00, 8'h01, 8'h01, 8'h02, 
-		  8'h02, 8'h03, 8'h03, 8'h04, 
-		  8'h06, 8'h07, 8'h09, 8'h0a, 
-		  8'h0c, 8'h0e, 8'h11, 8'h13, 
-		  8'h17, 8'h1b, 8'h20, 8'h25, 
-		  8'h2c, 8'h35, 8'h3e, 8'h47, 
-		  8'h54, 8'h66, 8'h77, 8'h88, 
-		  8'ha1, 8'hc0, 8'he0, 8'hff
-		};
-
-// Read from AY
+// Read from PSG
 assign DO = dout;
 reg [7:0] dout;
 always_comb begin
-	if(addr[7:4]) dout <= 8'hFF;
-	else begin
+	dout = 8'hFF;
+	if(~BDIR & BC & !addr[7:4]) begin
 		case(addr[3:0])
 			 0: dout = ymreg[0];
 			 1: dout = ymreg[1][3:0];
@@ -123,12 +112,15 @@ always_comb begin
 			11: dout = ymreg[11];
 			12: dout = ymreg[12];
 			13: dout = ymreg[13][3:0];
-			14: dout = (ymreg[7][6] ? ymreg[14] : IOA_in);
-			15: dout = (ymreg[7][7] ? ymreg[15] : IOB_in);
+			14: dout = ymreg[7][6] ? ymreg[14] : IOA_in;
+			15: dout = ymreg[7][7] ? ymreg[15] : IOB_in;
 		endcase
 	end
 end
 
+reg ena_div;
+reg ena_div_noise;
+
 //  p_divider
 always @(posedge CLK) begin
 	reg [3:0]  cnt_div;
@@ -150,7 +142,7 @@ always @(posedge CLK) begin
 end
 
 
-reg noise_gen_op;
+reg [2:0] noise_gen_op;
 
 //  p_noise_gen
 always @(posedge CLK) begin
@@ -166,9 +158,9 @@ always @(posedge CLK) begin
 				end else begin
 					noise_gen_cnt <= noise_gen_cnt + 1'd1;
 				end
-				noise_gen_op <= poly17[0];
+				noise_gen_op <= {3{poly17[0]}};
 			end else begin
-				noise_gen_op <= 0;
+				noise_gen_op <= ymreg[7][5:3];
 				noise_gen_cnt <= 0;
 			end
 		end
@@ -200,7 +192,7 @@ always @(posedge CLK) begin
 						tone_gen_cnt[i] <= tone_gen_cnt[i] + 1'd1;
 					end
 				end else begin
-					tone_gen_op[i] <= 0;
+					tone_gen_op[i] <= ymreg[7][i];
 					tone_gen_cnt[i] <= 0;
 				end
 			end
@@ -208,6 +200,7 @@ always @(posedge CLK) begin
 	end
 end
 
+reg env_ena;
 wire [15:0] env_gen_comp = {ymreg[12], ymreg[11]} ? {ymreg[12], ymreg[11]} - 1'd1 : 16'd0;
 
 //p_envelope_freq
@@ -227,14 +220,14 @@ always @(posedge CLK) begin
 	end
 end
 
+reg [4:0] env_vol;
+
 wire is_bot    = (env_vol == 5'b00000);
 wire is_bot_p1 = (env_vol == 5'b00001);
 wire is_top_m1 = (env_vol == 5'b11110);
 wire is_top    = (env_vol == 5'b11111);
 
 always @(posedge CLK) begin
-	reg old_BDIR;
-	reg env_reset;
 	reg env_hold;
 	reg env_inc;
 
@@ -260,82 +253,49 @@ always @(posedge CLK) begin
 	//
 	// 1 1 1 1  /___
 
-	if(RESET) begin
-		ymreg[0]  <= '0;
-		ymreg[1]  <= '0;
-		ymreg[2]  <= '0;
-		ymreg[3]  <= '0;
-		ymreg[4]  <= '0;
-		ymreg[5]  <= '0;
-		ymreg[6]  <= '0;
-		ymreg[7]  <= '1;
-		ymreg[8]  <= '0;
-		ymreg[9]  <= '0;
-		ymreg[10] <= '0;
-		ymreg[11] <= '0;
-		ymreg[12] <= '0;
-		ymreg[13] <= '0;
-		ymreg[14] <= '0;
-		ymreg[15] <= '0;
-		addr      <= '0;
-		env_vol   <= '0;
-	end else begin
-		old_BDIR <= BDIR;
-		if(~old_BDIR & BDIR) begin
-			if(BC) addr <= DI;
-			else if(!addr[7:4])begin
-				ymreg[addr[3:0]] <= DI;
-				env_reset <= (addr == 13);
-			end
-		end
-	end
-
-	if(CE) begin
-		if(env_reset) begin
-			env_reset <= 0;
-			// load initial state
-			if(!ymreg[13][2]) begin		// attack
-				env_vol <= 5'b11111;
-				env_inc <= 0;		// -1
-			end else begin
-				env_vol <= 5'b00000;
-				env_inc <= 1;		// +1
-			end
-			env_hold <= 0;
+	if(env_reset | RESET) begin
+		// load initial state
+		if(!ymreg[13][2]) begin		// attack
+			env_vol <= 5'b11111;
+			env_inc <= 0;		// -1
 		end else begin
+			env_vol <= 5'b00000;
+			env_inc <= 1;		// +1
+		end
+		env_hold <= 0;
+	end
+	else if(CE) begin
+		if (env_ena) begin
+			if (!env_hold) begin
+				if (env_inc) env_vol <= (env_vol + 5'b00001);
+					else env_vol <= (env_vol + 5'b11111);
+			end
 
-			if (env_ena) begin
-				if (!env_hold) begin
-					if (env_inc) env_vol <= (env_vol + 5'b00001);
-						else env_vol <= (env_vol + 5'b11111);
-				end
-
-				// envelope shape control.
-				if(!ymreg[13][3]) begin
-					if(!env_inc) begin	// down
-						if(is_bot_p1) env_hold <= 1;
-					end else if (is_top) env_hold <= 1;
-				end else if(ymreg[13][0]) begin		// hold = 1
-					if(!env_inc) begin	// down
-						if(ymreg[13][1]) begin		// alt
-							if(is_bot) env_hold <= 1;
-						end else if(is_bot_p1) env_hold <= 1;
-					end else if(ymreg[13][1]) begin	// alt
-						if(is_top) env_hold <= 1;
-					end else if(is_top_m1) env_hold <= 1;
-				end else if(ymreg[13][1]) begin		// alternate
-					if(env_inc == 1'b0) begin		// down
-						if(is_bot_p1) env_hold <= 1;
-						if(is_bot) begin
-							env_hold <= 0;
-							env_inc  <= 1;
-						end
-					end else begin
-						if(is_top_m1) env_hold <= 1;
-						if(is_top) begin
-							env_hold <= 0;
-							env_inc  <= 0;
-						end
+			// envelope shape control.
+			if(!ymreg[13][3]) begin
+				if(!env_inc) begin	// down
+					if(is_bot_p1) env_hold <= 1;
+				end else if (is_top) env_hold <= 1;
+			end else if(ymreg[13][0]) begin		// hold = 1
+				if(!env_inc) begin	// down
+					if(ymreg[13][1]) begin		// alt
+						if(is_bot) env_hold <= 1;
+					end else if(is_bot_p1) env_hold <= 1;
+				end else if(ymreg[13][1]) begin	// alt
+					if(is_top) env_hold <= 1;
+				end else if(is_top_m1) env_hold <= 1;
+			end else if(ymreg[13][1]) begin		// alternate
+				if(env_inc == 1'b0) begin		// down
+					if(is_bot_p1) env_hold <= 1;
+					if(is_bot) begin
+						env_hold <= 0;
+						env_inc  <= 1;
+					end
+				end else begin
+					if(is_top_m1) env_hold <= 1;
+					if(is_top) begin
+						env_hold <= 0;
+						env_inc  <= 0;
 					end
 				end
 			end
@@ -343,12 +303,29 @@ always @(posedge CLK) begin
 	end
 end
 
-wire [4:0] A = ~((ymreg[7][0] | tone_gen_op[1]) & (ymreg[7][3] | noise_gen_op)) ? 5'd0 : ymreg[8][4]  ? env_vol[4:0] : { ymreg[8][3:0],  ymreg[8][3]};
-wire [4:0] B = ~((ymreg[7][1] | tone_gen_op[2]) & (ymreg[7][4] | noise_gen_op)) ? 5'd0 : ymreg[9][4]  ? env_vol[4:0] : { ymreg[9][3:0],  ymreg[9][3]};
-wire [4:0] C = ~((ymreg[7][2] | tone_gen_op[3]) & (ymreg[7][5] | noise_gen_op)) ? 5'd0 : ymreg[10][4] ? env_vol[4:0] : {ymreg[10][3:0], ymreg[10][3]};
+reg [5:0] A,B,C;
+always @(posedge CLK) begin
+	A <= {MODE, ~((ymreg[7][0] | tone_gen_op[1]) & (ymreg[7][3] | noise_gen_op[0])) ? 5'd0 : ymreg[8][4]  ? env_vol[4:0] : { ymreg[8][3:0],  ymreg[8][3]}};
+	B <= {MODE, ~((ymreg[7][1] | tone_gen_op[2]) & (ymreg[7][4] | noise_gen_op[1])) ? 5'd0 : ymreg[9][4]  ? env_vol[4:0] : { ymreg[9][3:0],  ymreg[9][3]}};
+	C <= {MODE, ~((ymreg[7][2] | tone_gen_op[3]) & (ymreg[7][5] | noise_gen_op[2])) ? 5'd0 : ymreg[10][4] ? env_vol[4:0] : {ymreg[10][3:0], ymreg[10][3]}};
+end
 
-assign CHANNEL_A = MODE ? volTableAy[A[4:1]] : volTableYm[A];
-assign CHANNEL_B = MODE ? volTableAy[B[4:1]] : volTableYm[B];
-assign CHANNEL_C = MODE ? volTableAy[C[4:1]] : volTableYm[C];
+wire [7:0] volTable[64] = '{
+	//YM2149
+	8'h00, 8'h01, 8'h01, 8'h02, 8'h02, 8'h03, 8'h03, 8'h04, 
+	8'h06, 8'h07, 8'h09, 8'h0a, 8'h0c, 8'h0e, 8'h11, 8'h13, 
+	8'h17, 8'h1b, 8'h20, 8'h25, 8'h2c, 8'h35, 8'h3e, 8'h47, 
+	8'h54, 8'h66, 8'h77, 8'h88, 8'ha1, 8'hc0, 8'he0, 8'hff,
+
+	//AY8910
+	8'h00, 8'h00, 8'h03, 8'h03, 8'h04, 8'h04, 8'h06, 8'h06, 
+	8'h0a, 8'h0a, 8'h0f, 8'h0f, 8'h15, 8'h15, 8'h22, 8'h22, 
+	8'h28, 8'h28, 8'h41, 8'h41, 8'h5b, 8'h5b, 8'h72, 8'h72, 
+	8'h90, 8'h90, 8'hb5, 8'hb5, 8'hd7, 8'hd7, 8'hff, 8'hff 
+};
+
+assign CHANNEL_A = volTable[A];
+assign CHANNEL_B = volTable[B];
+assign CHANNEL_C = volTable[C];
 
 endmodule
diff --git a/src/sound/ym2203.sv b/src/sound/ym2203.sv
index e9ca0a4..09c1bc4 100644
--- a/src/sound/ym2203.sv
+++ b/src/sound/ym2203.sv
@@ -94,7 +94,7 @@ ym2149 ym2149
 	.CE(ce_psg),
 	.RESET(RESET),
 	.BDIR(WE),
-	.BC(~A0),
+	.BC(~A0 | ~WE),
 	.DI(DI),
 	.DO(psg_dout),
 	.CHANNEL_A(CHANNEL_A),