diff --git a/sound-driver/Makefile b/sound-driver/Makefile
index fa14a2a..ecdce2a 100644
--- a/sound-driver/Makefile
+++ b/sound-driver/Makefile
@@ -4,13 +4,12 @@ OBJDUMP=$(TOOLCHAIN_PREFIX)/bin/msp430-elf-objdump
 
 ARTIFACT=firmware
 MCU=msp430g2553
-COMMONFLAGS=-Wall -mmcu=$(MCU) -I $(TOOLCHAIN_PREFIX)/include -O0 -g0
+DEBUGFLAGS=
+# DEBUGFLAGS+= -g3 -ggdb -gdwarf-2
+COMMONFLAGS=-Wall -mmcu=$(MCU) -I $(TOOLCHAIN_PREFIX)/include -O0 -g0 $(DEBUGFLAGS)
 CFLAGS=$(COMMONFLAGS) -std=gnu99 
 ASFLAGS=$(COMMONFLAGS) -D__ASSEMBLER__
 
-# for debugging
-CFLAGS+= -g3 -ggdb -gdwarf-2
-
 LDFLAGS=-mmcu=$(MCU) -L $(TOOLCHAIN_PREFIX)/include
 
 $(ARTIFACT).elf:	main.o scheduler.o spi.o spi_init.o sequencer.o melody_tetris.o melody_tusch1.o psg.o mute.o melody_pling.o
diff --git a/sound-driver/main.c b/sound-driver/main.c
index 8e4a119..695eb33 100644
--- a/sound-driver/main.c
+++ b/sound-driver/main.c
@@ -31,7 +31,6 @@ int main() {
 
   __enable_interrupt();
 
-  // playMelodyTetris();
 
   while (1) {
     schExec();
diff --git a/sound-driver/melody_pling.c b/sound-driver/melody_pling.c
index 6b76b56..88ebacd 100644
--- a/sound-driver/melody_pling.c
+++ b/sound-driver/melody_pling.c
@@ -15,10 +15,10 @@ const t_tone plingVoice1[] = {
 };
 
 t_melodies pling = {
-  .melodies = { { .chip = 1, .amplitude = 12, .tones = plingVoice1 } },
+  .melodies = { { .amplitude = 12, .tones = plingVoice1 } },
   .numOfMelodies = 1,
   .pace = 200,
-  .slotMask = 0x02
+  .chip = 1
 };
 
 void playPling() {
diff --git a/sound-driver/melody_tetris.c b/sound-driver/melody_tetris.c
index 30091fb..598fe6c 100644
--- a/sound-driver/melody_tetris.c
+++ b/sound-driver/melody_tetris.c
@@ -922,15 +922,16 @@ const t_tone voice3[] = {
   { .octave = e_O_Null, .note = e_Null,  .length = e_L_EndMark, .legato = false, .staccato = false },
 };
 
+#define INITIAL_PACE 160
 t_melodies tetrisTheme = {
-  .melodies = { { .chip = 0, .amplitude = 8, .tones = voice1 }, { .chip = 0, .amplitude = 8, .tones = voice2 }, { .chip = 0, .amplitude = 8, .tones = voice3 } },
+  .melodies = { { .amplitude = 8, .tones = voice1 }, { .amplitude = 8, .tones = voice2 }, { .amplitude = 8, .tones = voice3 } },
   .numOfMelodies = 3,
-  .pace = 160,
-  .slotMask = 0x01
+  .pace = INITIAL_PACE,
+  .chip = 0
 };
 
 void playMelodyTetris() {
-  tetrisTheme.pace = 160; // reset to start value each time
+  tetrisTheme.pace = INITIAL_PACE; // reset to start value each time
   sequencerPlayMelodies(&tetrisTheme);
 }
 
diff --git a/sound-driver/melody_tusch1.c b/sound-driver/melody_tusch1.c
index a596ab2..8c61445 100644
--- a/sound-driver/melody_tusch1.c
+++ b/sound-driver/melody_tusch1.c
@@ -72,10 +72,10 @@ const t_tone tusch1voice3[] = {
 };
 
 t_melodies tusch1 = {
-  .melodies = { { .chip = 1, .amplitude = 12, .tones = tusch1voice1 }, { .chip = 1, .amplitude = 12, .tones = tusch1voice2 }, { .chip = 1, .amplitude = 12, .tones = tusch1voice3 } },
+  .melodies = { { .amplitude = 12, .tones = tusch1voice1 }, { .amplitude = 12, .tones = tusch1voice2 }, { .amplitude = 12, .tones = tusch1voice3 } },
   .numOfMelodies = 3,
   .pace = 200,
-  .slotMask = 0x02
+  .chip = 1
 };
 
 void playTusch1() {
diff --git a/sound-driver/psg.c b/sound-driver/psg.c
index b00dd6a..251e6bb 100644
--- a/sound-driver/psg.c
+++ b/sound-driver/psg.c
@@ -81,19 +81,6 @@ inline static void BUS_OP_CS1_DISABLE() {
   BUS_CTRL_REG |= _CS1;
 }
 
-#if 0
-static void delay() {
-asm volatile (
-    "push r12\n"
-    "mov.w #5, r12\n"
-    "loop:\n"
-    "dec.w r12\n"
-    "jnz loop\n"
-    "pop r12\n"
-);
-}
-#endif
-
 static uint8_t psgReadShadow(uint8_t chip, uint8_t address) {
   return psgShadowRegisters[chip][address];
 }
diff --git a/sound-driver/scheduler.c b/sound-driver/scheduler.c
index 74455c2..12f215c 100644
--- a/sound-driver/scheduler.c
+++ b/sound-driver/scheduler.c
@@ -52,16 +52,6 @@ uint16_t schAdd(void (*exec)(void *), void *handle, uint32_t delay, uint32_t per
   return taskId;
 }
 
-/*
-void schDel(void (*exec)(void *), void *handle) {
-  for (uint16_t i = 0; i < MAX_NUM_OF_TASKS; i++) {
-    if ((tasks[i].exec == exec) && (tasks[i].handle == handle)) {
-      tasks[i].exec = NULL;
-      break;
-    }
-  }
-}
-*/
 void schDel(uint16_t taskId) {
   tasks[taskId].exec = NULL;
 }
diff --git a/sound-driver/sequencer.c b/sound-driver/sequencer.c
index 9ffc25c..184cb76 100644
--- a/sound-driver/sequencer.c
+++ b/sound-driver/sequencer.c
@@ -59,7 +59,7 @@ void sequencerExec(void *handle) {
           if (melody->tones[melody->idx].length == e_L_EndMark) {
             melody->idx = 0;
           }
-          psgPlayTone(melody->chip, channel, melody->amplitude, melody->tones[melody->idx].octave, melody->tones[melody->idx].note);
+          psgPlayTone(melodies->chip, channel, melody->amplitude, melody->tones[melody->idx].octave, melody->tones[melody->idx].note);
           melody->lengthCnt = (melody->tones[melody->idx].staccato) ? 
             (calcLength(melodies, melody->tones[melody->idx].length) / 2) : 
             calcLength(melodies, melody->tones[melody->idx].length);
@@ -78,7 +78,7 @@ void sequencerExec(void *handle) {
         }
         break;
       case e_StaccatoBreak:
-        psgPlayTone(melody->chip, channel, 0, e_O_Null, e_Pause);
+        psgPlayTone(melodies->chip, channel, 0, e_O_Null, e_Pause);
         melody->lengthCnt = calcLength(melodies, melody->tones[melody->idx].length) / 2;
         melody->state = e_HoldStaccatoBreak;
         break;
@@ -90,7 +90,7 @@ void sequencerExec(void *handle) {
         break;
       case e_SeparateTone:
         if (! (melody->tones[melody->idx].legato)) {
-          psgPlayTone(melody->chip, channel, 0, e_O_Null, e_Pause);
+          psgPlayTone(melodies->chip, channel, 0, e_O_Null, e_Pause);
         }
         melody->idx += 1;
         melody->state = e_PlayTone;
@@ -106,6 +106,8 @@ void sequencerExec(void *handle) {
 }
 
 void sequencerPlayMelodies(t_melodies *melodies) {
+  melodies->slotMask = (1 << melodies->chip);
+
   if ((slots & melodies->slotMask) != 0) {
     return;
   }
@@ -123,8 +125,11 @@ void sequencerPlayMelodies(t_melodies *melodies) {
 }
 
 void sequencerStopMelodies(t_melodies *melodies) {
-  slots &= ~(melodies->slotMask);
   schDel(melodies->taskId);
+  slots &= ~(melodies->slotMask);
+  for (uint8_t channel = 0; channel < melodies->numOfMelodies; channel++) {
+    psgPlayTone(melodies->chip, channel, 0, e_O_Null, e_Pause);
+  }
 }
 
 void sequencerChangePace(t_melodies *melodies) {
diff --git a/sound-driver/sequencer.h b/sound-driver/sequencer.h
index bdb4fd6..7411ae9 100644
--- a/sound-driver/sequencer.h
+++ b/sound-driver/sequencer.h
@@ -42,7 +42,6 @@ typedef enum {
 
 typedef struct {
   uint16_t idx;
-  uint8_t chip;
   uint16_t lengthCnt;
   t_sequencerState state;
   uint8_t amplitude;
@@ -53,10 +52,11 @@ typedef struct {
 #define NUM_OF_CHANNELS 3
 typedef struct {
   uint8_t slotMask;
+  uint8_t chip;
   uint8_t taskId;
   uint16_t quarterLength;
   uint8_t numOfMelodies;
-  uint8_t pace; // quarter notes per minute
+  uint16_t pace; // quarter notes per minute
   uint8_t sync;
   t_melody melodies[NUM_OF_CHANNELS];
 } t_melodies;
diff --git a/sound-driver/spi.S b/sound-driver/spi.S
index c8d4864..97358e2 100644
--- a/sound-driver/spi.S
+++ b/sound-driver/spi.S
@@ -1,10 +1,6 @@
 #include <msp430g2553.h>
 #include "soundCodes.h"
 
-  .section ".data"
-  .global cmd
-cmd:
-  .byte   
 
   .section ".text","ax",@progbits
 receive_isr:
@@ -34,7 +30,7 @@ spiCmdHandler_3:
 spiCmdHandler_4:
   bit     #SOUND_GAMEOVER, &cmd
   jz      spiCmdHandler_5
-  ;; insert a call here
+  call    #stopMelodyTetris
   bic     #SOUND_GAMEOVER, &cmd
 spiCmdHandler_5:
   bit     #SOUND_FANFARE, &cmd
@@ -59,9 +55,6 @@ spiCmdHandler_8:
 spiCmdHandler_end:
   ret
 
- 
-
-
 
   .section "__interrupt_vector_8","ax",@progbits
   .word   receive_isr
diff --git a/sound-driver/spi_init.c b/sound-driver/spi_init.c
index 5d831b1..fdef72c 100644
--- a/sound-driver/spi_init.c
+++ b/sound-driver/spi_init.c
@@ -6,7 +6,7 @@
 #include "soundCodes.h"
 
 
-extern uint8_t cmd;
+uint8_t cmd;
 
 void spiInit() {
   // SPI slave