diff --git a/m68k/interrupt.cpp b/m68k/interrupt.cpp
index d115e43..c3911ed 100644
--- a/m68k/interrupt.cpp
+++ b/m68k/interrupt.cpp
@@ -6,27 +6,33 @@ extern void * _jojo_start __asm("_binary_jojo_11025_s16be_1ch_pcm_start");
 
 static volatile int32_t frame = 0;
 
+constexpr int32_t tactl = 7;
+constexpr int32_t frame_size = ((1 << tactl) * 256) / (44100 / 11025);
+constexpr int32_t frame_count = 507150 / (frame_size * 2);
+constexpr int32_t tima = 0;
+
 extern "C"
 void auto_vector_1(void) __attribute__ ((interrupt_handler));
 void auto_vector_1(void)
 {
   // reset TIMER_A interrupt
   scsp.reg.ctrl.SCIRE = INT__TIMER_A;
+  scsp.reg.ctrl.TIMA = TIMA__TACTL(tactl) | TIMA__TIMA(tima);
 
-  frame++;
-  //if (frame > 3962) frame = 0;
+  if (frame > frame_count) frame = 0;
   
   const uint16_t * jojo_start = reinterpret_cast<uint16_t *>(&_jojo_start);
-  const uint32_t frame_addr = reinterpret_cast<uint32_t>(&jojo_start[frame * 8192]);
-  
-  scsp_slot& slot = scsp.reg.slot[frame % 32];
-  slot.LOOP = 0;
-  slot.LOOP |= LOOP__KYONEX;
+  const uint32_t frame_addr = reinterpret_cast<uint32_t>(&jojo_start[frame * frame_size]);
   
+  scsp_slot& slotp = scsp.reg.slot[(frame - 1) % 32];
+  slotp.LOOP = 0;
+  slotp.LOOP |= LOOP__KYONEX;
+
+  scsp_slot& slot = scsp.reg.slot[(frame) % 32];
   slot.LOOP = LOOP__KYONB | LOOP__SA(frame_addr); // kx kb sbctl[1:0] ssctl[1:0] lpctl[1:0] 8b sa[19:16]
   slot.SA = SA__SA(frame_addr); // start address (bytes)
   slot.LSA = 0; // loop start address (samples)
-  slot.LEA = 8192; // loop end address (samples)
+  slot.LEA = frame_size; // loop end address (samples)
   slot.EG = EG__AR(0x1f) | EG__EGHOLD; // d2r d1r ho ar krs dl rr
   slot.VOLUME = 0; // stwinh sdir tl
   slot.FM = 0; // mdl mdxsl mdysl
@@ -35,6 +41,8 @@ void auto_vector_1(void)
   slot.MIXER = MIXER__DISDL(0b101); // disdl dipan efsdl efpan
 
   slot.LOOP |= LOOP__KYONEX;
+
+  frame++;
   
   return;
 }
@@ -42,11 +50,15 @@ void auto_vector_1(void)
 void main()
 {
   for (long i = 0; i < 807; i++) { asm volatile ("nop"); }   // wait for (way) more than 30µs
-  
+ 
+  for (int i = 0; i < 32; i++) {
+    scsp_slot& slot = scsp.reg.slot[i];
+    slot.LOOP = 0;
+    slot.LOOP |= LOOP__KYONEX;
+  }
+
   scsp.reg.ctrl.MIXER = MIXER__MEM4MB | MIXER__MVOL(0xf);
-
-  scsp.reg.ctrl.TIMA = TIMA__TACTL(7);
-
+  
   // timer A is vector 1 (0b001)
   scsp.reg.ctrl.SCILV2 = 0;
   scsp.reg.ctrl.SCILV1 = 0;
@@ -55,12 +67,14 @@ void main()
   // enable TIMER_A
   scsp.reg.ctrl.SCIRE = INT__TIMER_A;
   scsp.reg.ctrl.SCIEB = INT__TIMER_A;
+
+  scsp.reg.ctrl.TIMA = TIMA__TACTL(tactl) | TIMA__TIMA(tima);  
   
   asm volatile ("move.w #8192,%sr");
 
+  /*
   const uint16_t * jojo_start = reinterpret_cast<uint16_t *>(&_jojo_start);
   const uint32_t frame_addr = reinterpret_cast<uint32_t>(&jojo_start[frame * 128]);
-  
   scsp_slot& slot = scsp.reg.slot[0];
   slot.LOOP = 0;
   slot.LOOP |= LOOP__KYONEX;
@@ -76,13 +90,6 @@ void main()
   slot.LFO = 0; // lfof plfows
   slot.MIXER = MIXER__DISDL(0b101); // disdl dipan efsdl efpan
 
-  slot.LOOP |= LOOP__KYONEX;  
+  slot.LOOP |= LOOP__KYONEX;
+  */
 }
-
-extern "C"
-void start(void)
-{
-  main();
-  while (1);
-}
-
diff --git a/m68k/slot.cpp b/m68k/slot.cpp
index adc9e6b..86bfeb5 100644
--- a/m68k/slot.cpp
+++ b/m68k/slot.cpp
@@ -29,10 +29,3 @@ void main()
 
   slot.LOOP |= LOOP__KYONEX;
 }
-
-extern "C"
-void start(void)
-{
-  main();
-  while (1);
-}