diff --git a/apple/mouse-rom.h b/apple/mouse-rom.h
index ba2b739..134e81f 100644
--- a/apple/mouse-rom.h
+++ b/apple/mouse-rom.h
@@ -16,7 +16,7 @@ static
 0x68, 0xAA, 0x68, 0xEA, 0x68, 0x99, 0x80, 0xC0, 
 0x60, 0x99, 0x81, 0xC0, 0x68, 0xBD, 0x38, 0x06, 
 0xAA, 0x68, 0xA8, 0x68, 0xBD, 0x00, 0x02, 0x60, 
-0xC9, 0x0A, 0xB0, 0x04, 0x8D, 0xCF, 0xC0, 0x60, 
+0xC9, 0x10, 0xB0, 0x04, 0x8D, 0xCF, 0xC0, 0x60, 
 0x38, 0x60, 0x48, 0x78, 0x8D, 0xCE, 0xC0, 0xA2, 
 0x04, 0xBD, 0xB8, 0x06, 0x29, 0x0E, 0xD0, 0x01, 
 0x38, 0x68, 0x60, 0x8D, 0xCB, 0xC0, 0x18, 0x60, 
diff --git a/apple/mouse.cpp b/apple/mouse.cpp
index aa29c91..8a82ff6 100644
--- a/apple/mouse.cpp
+++ b/apple/mouse.cpp
@@ -10,6 +10,8 @@
 enum {
   SW_W_INITPR     = 0x00,
   SW_W_HANDLEIN   = 0x01,
+
+  SW_R_ERR        = 0x07,
   
   SW_R_HOMEMOUSE  = 0x08,
   SW_R_POSMOUSE   = 0x09,
@@ -159,6 +161,7 @@ void Mouse::writeSwitches(uint8_t s, uint8_t v)
     g_vm->getMMU()->write(0x778+4, interruptsTriggered);
     g_vm->getMMU()->write(0x6B8+4, interruptsTriggered); // hack to appease ROM
     interruptsTriggered = 0;
+    g_cpu->deassertIrq();
     break;
   case SW_W_CLAMPMOUSE:
     {
@@ -198,7 +201,7 @@ void Mouse::loadROM(uint8_t *toWhere)
     toWhere[i] = pgm_read_byte(&romData[i]);
   }
 #else
-  printf("loading HD32 rom\n");
+  printf("loading Mouse rom\n");
   memcpy(toWhere, romData, 256);
 #endif
 }
@@ -216,11 +219,10 @@ void Mouse::maintainMouse(int64_t cycleCount)
 {
   // Fake a 60Hz VBL in case we need it for our interrupts
   static int64_t nextInterruptTime = cycleCount + 17050;
-  
   if ( (status & ST_MOUSEENABLE) &&
        (status & ST_INTVBL)  &&
        (cycleCount >= nextInterruptTime) ) {
-    g_cpu->irq();
+    g_cpu->assertIrq();
     
     interruptsTriggered |= ST_INTVBL;
     
@@ -232,14 +234,14 @@ void Mouse::maintainMouse(int64_t cycleCount)
     if ( (status & ST_MOUSEENABLE) &&
 	 (status & ST_INTMOUSE) &&
 	 (xpos != lastXForInt || ypos != lastYForInt) ) {
-      g_cpu->irq();
+      g_cpu->assertIrq();
       
       interruptsTriggered |= ST_INTMOUSE;      
       lastXForInt = xpos; lastYForInt = ypos;
     } else if ( (status & ST_MOUSEENABLE) &&
 		(status & ST_INTBUTTON) &&
 		lastButtonForInt != g_mouse->getButton()) {
-      g_cpu->irq();
+      g_cpu->assertIrq();
 
       interruptsTriggered |= ST_INTBUTTON;
       lastButtonForInt = g_mouse->getButton();
diff --git a/apple/mouserom.asm b/apple/mouserom.asm
index a176d24..dfe1c65 100644
--- a/apple/mouserom.asm
+++ b/apple/mouserom.asm
@@ -85,7 +85,7 @@ INHandler:
 	RTS
 
 SetMouse:
-	CMP	#$0A		; values >= 10 are invalid
+	CMP	#$10		; values >= $10 are invalid
 	BCS	ExitWithError
 	STA	$C0CF		; soft switch 0x0F, hard-coded slot 4 for now
 	RTS
diff --git a/apple/mouserom.lst b/apple/mouserom.lst
index a5699ea..076edc0 100644
--- a/apple/mouserom.lst
+++ b/apple/mouserom.lst
@@ -89,7 +89,7 @@ Current file: mouserom.asm
 00C45F  1  60           	RTS
 00C460  1               
 00C460  1               SetMouse:
-00C460  1  C9 0A        	CMP	#$0A		; values >= 10 are invalid
+00C460  1  C9 10        	CMP	#$10		; values >= $10 are invalid
 00C462  1  B0 04        	BCS	ExitWithError
 00C464  1  8D CF C0     	STA	$C0CF		; soft switch 0x0F, hard-coded slot 4 for now
 00C467  1  60           	RTS
diff --git a/cpu.cpp b/cpu.cpp
index 532a3b1..461fd69 100644
--- a/cpu.cpp
+++ b/cpu.cpp
@@ -444,6 +444,16 @@ void Cpu::brk()
   cycles += 2;
 }
 
+void Cpu::assertIrq()
+{
+  irqPending = true;
+}
+
+void Cpu::deassertIrq()
+{
+  irqPending = false;
+}
+
 void Cpu::irq()
 {
   // If interrupts are disabled, then do nothing
@@ -472,7 +482,6 @@ uint8_t Cpu::Run(uint8_t numSteps)
 uint8_t Cpu::step()
 {
   if (irqPending) {
-    irqPending = false;
     irq();
   }
 
@@ -1217,11 +1226,6 @@ uint16_t Cpu::popS16()
   return (msb << 8) | lsb;
 }
 
-void Cpu::stageIRQ()
-{
-  irqPending = true;
-}
-
 void Cpu::realtime()
 {
   realtimeProcessing = true;
diff --git a/cpu.h b/cpu.h
index a90a59a..13b9fb3 100644
--- a/cpu.h
+++ b/cpu.h
@@ -151,6 +151,9 @@ class Cpu {
   void brk();
   void irq();
 
+  void assertIrq();
+  void deassertIrq();
+
   uint8_t Run(uint8_t numSteps);
   uint8_t step();
 
@@ -161,8 +164,6 @@ class Cpu {
   uint8_t SP();
   uint8_t P();
 
-  void stageIRQ();
-
  protected:
   // Stack manipulation
   void pushS8(uint8_t b);