diff --git a/src/py65/mpu6502.py b/src/py65/mpu6502.py
index ab5dcb0..8070bc4 100644
--- a/src/py65/mpu6502.py
+++ b/src/py65/mpu6502.py
@@ -15,7 +15,7 @@ class MPU:
   ZERO      = 2
   CARRY     = 1
 
-  def __init__(self):
+  def __init__(self, memory=None, pc=0):
     # config
     self.debug = False
     
@@ -26,8 +26,13 @@ class MPU:
     self.processorCycles = 0
     self.internalCycleDelay = 0
 
+    if not memory:
+        memory = 0xFFFF * [0x00]
+    self.memory = memory
+    self.start_pc = pc
+
     # init
-    self.clearMemory()
+    #self.clearMemory()
     self.reset()
 
   def __repr__(self):
@@ -48,17 +53,19 @@ class MPU:
     return self
 
   def reset(self):
-    self.pc=0
-    self.sp=255
-    self.a=self.x=self.y=0
-    self.flags=32
-    self.breakFlag=False
-    self.processorCycles=0
+    self.pc = self.start_pc
+    self.sp = 255
+    self.a = 0
+    self.x = 0
+    self.y = 0
+    self.flags = 32
+    self.breakFlag = False
+    self.processorCycles = 0
 
-  def clearMemory(self, start=0x0000, end=0xFFFF):
-    self.memory = [] 
-    for addr in range(start, end + 1):
-      self.memory.insert(addr, 0x00)
+  #def clearMemory(self, start=0x0000, end=0xFFFF):
+    #self.memory = [] 
+    #for addr in range(start, end + 1):
+      #self.memory.insert(addr, 0x00)
 
   def ByteAt(self, addr):
     return self.memory[addr]