diff --git a/core/cpu.c b/core/cpu.c
index 39e978e..9024966 100644
--- a/core/cpu.c
+++ b/core/cpu.c
@@ -91,11 +91,6 @@
 #define CPU_XORBSU   82
 #define CPU_XORNBSU  83
 
-/* Functional operand types */
-#define CPU_LITERAL  0
-#define CPU_MEMORY   1
-#define CPU_REGISTER 2
-
 /* Bit string operations */
 #define CPU_AND_BS  0
 #define CPU_ANDN_BS 1
diff --git a/core/vb.c b/core/vb.c
index 146f016..c73497f 100644
--- a/core/vb.c
+++ b/core/vb.c
@@ -643,6 +643,7 @@ VBAPI vbOnWrite vbGetWriteCallback(VB *sim) {
 VBAPI VB* vbInit(VB *sim) {
     sim->cart.ram        = NULL;
     sim->cart.rom        = NULL;
+    sim->ph.enabled      = 0;
     sim->vsu.out.samples = NULL;
     sim->onExecute       = NULL;
     sim->onFetch         = NULL;
@@ -652,7 +653,7 @@ VBAPI VB* vbInit(VB *sim) {
     sim->onSamples       = NULL;
     sim->onWrite         = NULL;
     sim->peer            = NULL;
-    sim->ph.enabled      = 0;
+    sim->tag             = NULL;
     vbReset(sim);
     return sim;
 }
@@ -716,28 +717,28 @@ VBAPI int vbSetCartROM(VB *sim, void *rom, uint32_t size) {
 /* Specify a new exception callback handler */
 VBAPI vbOnException vbSetExceptionCallback(VB *sim, vbOnException callback) {
     vbOnException prev = sim->onException;
-    sim->onException = callback;
+    sim->onException   = callback;
     return prev;
 }
 
 /* Specify a new execute callback handler */
 VBAPI vbOnExecute vbSetExecuteCallback(VB *sim, vbOnExecute callback) {
     vbOnExecute prev = sim->onExecute;
-    sim->onExecute = callback;
+    sim->onExecute   = callback;
     return prev;
 }
 
 /* Specify a new fetch callback handler */
 VBAPI vbOnFetch vbSetFetchCallback(VB *sim, vbOnFetch callback) {
     vbOnFetch prev = sim->onFetch;
-    sim->onFetch = callback;
+    sim->onFetch   = callback;
     return prev;
 }
 
 /* Specify a new frame callback handler */
 VBAPI vbOnFrame vbSetFrameCallback(VB *sim, vbOnFrame callback) {
     vbOnFrame prev = sim->onFrame;
-    sim->onFrame = callback;
+    sim->onFrame   = callback;
     return prev;
 }
 
@@ -749,7 +750,7 @@ VBAPI uint16_t vbSetKeys(VB *sim, uint16_t keys) {
 /* Specify a new link callback handler */
 VBAPI vbOnLink vbSetLinkCallback(VB *sim, vbOnLink callback) {
     vbOnLink prev = sim->onLink;
-    sim->onLink = callback;
+    sim->onLink   = callback;
     return prev;
 }
 
@@ -774,6 +775,8 @@ VBAPI int vbSetOption(VB *sim, int key, int value) {
 VBAPI void vbSetPeer(VB *sim, VB *peer) {
     if (sim->peer == peer)
         return;
+    if (sim->peer != NULL)
+        sim->peer->peer = NULL;
     sim->peer = peer;
     if (peer == NULL)
         return;
@@ -784,6 +787,7 @@ VBAPI void vbSetPeer(VB *sim, VB *peer) {
 
 /* Specify a new value for the program counter */
 VBAPI uint32_t vbSetProgramCounter(VB *sim, uint32_t value) {
+    sim->cpu.clocks    = 0;
     sim->cpu.operation = CPU_FETCH;
     sim->cpu.pc        = sim->cpu.nextPC = value & 0xFFFFFFFE;
     sim->cpu.step      = 0;
@@ -798,7 +802,7 @@ VBAPI int32_t vbSetProgramRegister(VB *sim, unsigned index, int32_t value) {
 /* Specify a new read callback handler */
 VBAPI vbOnRead vbSetReadCallback(VB *sim, vbOnRead callback) {
     vbOnRead prev = sim->onRead;
-    sim->onRead = callback;
+    sim->onRead   = callback;
     return prev;
 }
 
@@ -829,7 +833,7 @@ VBAPI uint32_t vbSetSystemRegister(VB *sim, unsigned index, uint32_t value) {
 /* Specify a new write callback handler */
 VBAPI vbOnWrite vbSetWriteCallback(VB *sim, vbOnWrite callback) {
     vbOnWrite prev = sim->onWrite;
-    sim->onWrite = callback;
+    sim->onWrite   = callback;
     return prev;
 }
 
@@ -841,7 +845,7 @@ VBAPI size_t vbSizeOf() {
 /* Specify a simulation's userdata pointer */
 VBAPI void* vbSetUserData(VB *sim, void *tag) {
     void *prev = sim->tag;
-    sim->tag = tag;
+    sim->tag   = tag;
     return prev;
 }
 
diff --git a/core/vsu.c b/core/vsu.c
index 9c16c25..706564b 100644
--- a/core/vsu.c
+++ b/core/vsu.c
@@ -345,7 +345,7 @@ static void vsuEmulate(VB *sim, uint32_t clocks) {
 
         /* Wait for the current sample to finish */
         if (sim->vsu.clocks != 0)
-            continue;
+            return;
 
         /* Compute the output sample */
         output[0] = output[1] = 0;