diff --git a/se/sics/mspsim/chip/Button.java b/se/sics/mspsim/chip/Button.java
index 8a9f47f..e076ec3 100644
--- a/se/sics/mspsim/chip/Button.java
+++ b/se/sics/mspsim/chip/Button.java
@@ -76,6 +76,6 @@ public class Button extends Chip {
 
     @Override
     public String info() {
-        return id + ": " + (isPressed ? "pressed" : "released");
+        return " Button is " + (isPressed ? "pressed" : "not pressed");
     }
 }
diff --git a/se/sics/mspsim/core/Chip.java b/se/sics/mspsim/core/Chip.java
index 01e4b7e..e23901c 100644
--- a/se/sics/mspsim/core/Chip.java
+++ b/se/sics/mspsim/core/Chip.java
@@ -69,9 +69,6 @@ public abstract class Chip implements Loggable, EventSource {
 
   public Chip(String id, MSP430Core cpu) {
     this(id, id, cpu);
-    if (cpu != null) {
-        logger = cpu.getLogger();
-    }
   }
 
   public Chip(String id, String name, MSP430Core cpu) {
diff --git a/se/sics/mspsim/core/IOPort.java b/se/sics/mspsim/core/IOPort.java
index 1051098..aeed7a8 100644
--- a/se/sics/mspsim/core/IOPort.java
+++ b/se/sics/mspsim/core/IOPort.java
@@ -116,9 +116,9 @@ public class IOPort extends IOUnit {
         String[] specs = specification.split(",");
         int port = specs[0].charAt(1) - '0';
         int offset = Integer.parseInt(specs[0].substring(3), 16);
-        
+
         PortReg[] portMap = new PortReg[0x20]; /* Worst case port-map */
-        
+        int highest = -1;
         for (int i = 1; i < specs.length; i++) {
             String[] preg = specs[i].split(" ");
             PortReg pr = PortReg.valueOf(preg[0]);
@@ -127,6 +127,12 @@ public class IOPort extends IOUnit {
                 portMap = Arrays.copyOf(portMap, offs + 1);
             }
             portMap[offs] = pr;
+            if (offs > highest) {
+                highest = offs;
+            }
+        }
+        if (highest + 1 < portMap.length) {
+            portMap = Arrays.copyOf(portMap, highest + 1);
         }
         IOPort newPort = new IOPort(cpu, port, interrupt, cpu.memory, offset, portMap);
         if (last != null && offset == last.offset && offset > 0) {
@@ -171,7 +177,7 @@ public class IOPort extends IOUnit {
         timerCapture[pin] = timer;
     }
 
-    public void updateIV() {
+    private void updateIV() {
         int bitval = 0x01;
         iv = 0;
         int ie_ifg = ifg & ie;
@@ -183,6 +189,7 @@ public class IOPort extends IOUnit {
             bitval = bitval << 1;
         }
         //System.out.println("*** Setting IV to: " + iv + " ifg: " + ifg);
+        cpu.flagInterrupt(interrupt, this, (ifg & ie) > 0);
     }
 
     public int getRegister(PortReg register) {
@@ -216,7 +223,7 @@ public class IOPort extends IOUnit {
     }
 
     /* only byte access!!! */
-    int read_port(PortReg function, long cycles) {
+    private int readPort(PortReg function, long cycles) {
         switch(function) {
         case OUT:
             return out;
@@ -238,18 +245,27 @@ public class IOPort extends IOUnit {
             return sel2;
         case DS:
             return ds;
-        case IV_L:
-            return iv & 0xff;
-        case IV_H:
-            int v = iv >> 8;
-            updateIV();
+        case IV_L: {
+            int v = iv & 0xff;
+            // Clear highest interrupt
+            if (iv != 0) {
+                if (iv > 1 && iv < 17) {
+                    ifg &= ~(1 << ((iv - 2) / 2));
+                }
+                updateIV();
+            }
             return v;
         }
+        case IV_H: {
+            int v = iv >> 8;
+            return v;
+        }
+        }
         /* default is zero ??? */
         return 0;
     }
 
-    void write_port(PortReg function, int data, long cycles) {
+    private void writePort(PortReg function, int data, long cycles) {
         switch(function) {
         case OUT: {
             out = data;
@@ -279,11 +295,10 @@ public class IOPort extends IOUnit {
             break;
         case IFG:
             if (DEBUG) {
-                log("Clearing IFlag: " + data);
+                log("Setting IFlag: " + data);
             }
-            ifg &= data;
+            ifg = data;
             updateIV();
-            cpu.flagInterrupt(interrupt, this, (ifg & ie) > 0);
             break;
         case IE:
             ie = data;
@@ -301,15 +316,21 @@ public class IOPort extends IOUnit {
         case SEL2:
             sel2 = data;
             break;
-            /* Can IV be written ? */
         case DS:
             ds = data;
             break;
         case IV_L:
-            iv = (iv & 0xff00) | data;
+            // IV can not be written but highest interrupt should be cleared
+            // on access.
+            if (iv != 0) {
+                if (iv > 1 && iv < 17) {
+                    ifg &= ~(1 << ((iv - 2) / 2));
+                }
+                updateIV();
+            }
             break;
         case IV_H:
-            iv = (iv & 0x00ff) | (data << 8);
+            // IV_H can not be written
             break;
         }
     }
@@ -319,22 +340,19 @@ public class IOPort extends IOUnit {
         PortReg reg = portMap[address - offset];
         /* only byte read allowed if not having an ioPair */
         if (word && reg == PortReg.IV_L) {
-            /* Always read low first then high => update on high!!! */
-            return read_port(reg, cycles) | (read_port(PortReg.IV_H, cycles) << 8);
+            /* Read hi first then low => update on low!!! */
+            return (readPort(PortReg.IV_H, cycles) << 8) | readPort(reg, cycles);
         } else if (word && ioPair != null) {
             /* read same function from both */
-            return read_port(reg, cycles) | (ioPair.read_port(reg, cycles) << 8);
+            return readPort(reg, cycles) | (ioPair.readPort(reg, cycles) << 8);
         }
         /* NOTE: read of PIV might be wrong here - might be word access on IV? */
-        return read_port(reg, cycles);
+        return readPort(reg, cycles);
     }
 
 
     public void write(int address, int data, boolean word, long cycles) {
         int iAddress = address - offset;
-        if (iAddress < 0 || iAddress >= portMap.length) {
-            throw new EmulationException("Writing to illegal IO port address at " + getID() + ": $" + Utils.hex(address, 4));
-        }
         PortReg fun = portMap[iAddress];
         if (DEBUG) {
             log("Writing to " + getID() + fun +
@@ -345,10 +363,10 @@ public class IOPort extends IOUnit {
 
         /* only byte write - need to convert any word write here... */
         if (word && ioPair != null) {
-            write_port(fun, data & 0xff, cycles);
-            ioPair.write_port(fun, data >> 8, cycles);
+            writePort(fun, data & 0xff, cycles);
+            ioPair.writePort(fun, data >> 8, cycles);
         } else {
-            write_port(fun, data, cycles);
+            writePort(fun, data, cycles);
         }
     }
 
@@ -370,23 +388,21 @@ public class IOPort extends IOUnit {
                     // LO/HI transition
                     if (state == PinState.HI) {
                         ifg |= bit;
-                        updateIV();
                         if (DEBUG) {
                             log("Flagging interrupt (HI): " + bit);
                         }
+                        updateIV();
                     }
                 } else {
                     // HI/LO transition
                     if (state == PinState.LOW) {
                         ifg |= bit;
-                        updateIV();
                         if (DEBUG) {
                             log("Flagging interrupt (LOW): " + bit);
                         }
+                        updateIV();
                     }
                 }
-                // Maybe this is not the only place where we should flag int?
-                cpu.flagInterrupt(interrupt, this, (ifg & ie) > 0);
             }
 
             if (timerCapture[pin] != null) {
diff --git a/se/sics/mspsim/core/IOUnit.java b/se/sics/mspsim/core/IOUnit.java
index 71bb834..876ef3a 100644
--- a/se/sics/mspsim/core/IOUnit.java
+++ b/se/sics/mspsim/core/IOUnit.java
@@ -36,9 +36,6 @@
  */
 
 package se.sics.mspsim.core;
-
-import java.io.PrintStream;
-
 import se.sics.mspsim.core.EmulationLogger.WarningType;
 
 public abstract class IOUnit implements InterruptHandler, Loggable {
@@ -53,11 +50,10 @@ public abstract class IOUnit implements InterruptHandler, Loggable {
   private StateChangeListener stateListener;
   private int ioState;
   protected int logLevel;
-  
-  protected EmulationLogger logger;
-  private PrintStream log;
   protected boolean DEBUG = false;
 
+  protected EmulationLogger logger;
+
   public IOUnit(String id, MSP430Core cpu, int[] memory, int offset) {
     this(id, id, cpu, memory, offset);
   }
@@ -79,8 +75,9 @@ public abstract class IOUnit implements InterruptHandler, Loggable {
   @Override 
   public void setLogLevel(int l) {
       logLevel = l;
+      DEBUG = logLevel == Loggable.DEBUG;
   }
-  
+
   public void addStateChangeListener(StateChangeListener listener) {
       stateListener = StateChangeListener.Proxy.INSTANCE.add(stateListener, listener);
   }
diff --git a/se/sics/mspsim/platform/wismote/WismoteNode.java b/se/sics/mspsim/platform/wismote/WismoteNode.java
index d2b2853..c42251b 100644
--- a/se/sics/mspsim/platform/wismote/WismoteNode.java
+++ b/se/sics/mspsim/platform/wismote/WismoteNode.java
@@ -67,8 +67,8 @@ public class WismoteNode extends GenericNode implements PortListener, USARTListe
     /* P4.4 - Output: RESET_N to CC2520 */
     public static final int CC2520_RESET = 1 << 4;
 
-    /* P2.7 - Button */
-    public static final int BUTTON_PIN = 7;
+    /* P1.4 - Button */
+    public static final int BUTTON_PIN = 4;
 
     /* P8.6 - Red (left) led */
     private static final int LEDS_CONF_RED2   = 1 << 6;
@@ -173,7 +173,7 @@ public class WismoteNode extends GenericNode implements PortListener, USARTListe
             throw new EmulationException("Could not setup wismote mote - missing USCI B0");
         }
         leds = new Leds(cpu, LEDS);
-        button = new Button("Button", cpu, port2, BUTTON_PIN, true);
+        button = new Button("Button", cpu, port1, BUTTON_PIN, true);
 
         IOUnit usart = cpu.getIOUnit("USCI A1");
         if (usart instanceof USARTSource) {
diff --git a/se/sics/mspsim/util/ELF.java b/se/sics/mspsim/util/ELF.java
index 4909eff..e4b0e01 100644
--- a/se/sics/mspsim/util/ELF.java
+++ b/se/sics/mspsim/util/ELF.java
@@ -27,16 +27,12 @@
  *
  * This file is part of MSPSim.
  *
- * $Id$
- *
  * -----------------------------------------------------------------
  *
  * ELF
  *
  * Author  : Joakim Eriksson
  * Created : Sun Oct 21 22:00:00 2007
- * Updated : $Date$
- *           $Revision$
  */
 
 package se.sics.mspsim.util;
@@ -54,7 +50,7 @@ import se.sics.mspsim.debug.StabDebug;
 
 public class ELF {
 
-  private static final int EI_NIDENT = 16;
+  // private static final int EI_NIDENT = 16;
   private static final int EI_ENCODING = 5;
   private static final int[] MAGIC = new int[] {0x7f, 'E', 'L', 'F'};
   
@@ -97,28 +93,22 @@ public class ELF {
 
   /* check if the file exists and is an ELF file */
   public static boolean isELF(File file) {
-    InputStream input = null;
     try {
-      input = new BufferedInputStream(new FileInputStream(file));
+      InputStream input = new BufferedInputStream(new FileInputStream(file));
       for (int i = 0; i < MAGIC.length; i++) {
         if (MAGIC[i] != input.read()) {
+          input.close();
           return false;
         }
       }
+      input.close();
+      return true;
     } catch(IOException ioe) {
       // ignore and return false - this is not an elf.
       return false;
-    } finally {
-      if (input != null) {
-        try {
-          input.close();
-        } catch (Exception e) {
-        }
-      }
     }
-    return true;
   }
-  
+
   private void readHeader() throws ELFException {
     for (int i = 0; i < MAGIC.length; i++) {
       if (elfData[i] != (byte) (MAGIC[i] & 0xff)) {
@@ -465,10 +455,10 @@ public class ELF {
       addr += symTable.getEntrySize();
     }
 
-  if (sAddrHighest > 0) {
-    System.out.printf("Warning: Unable to parse _end symbol. I'm guessing that heap starts at 0x%05x\n", sAddrHighest);
-    map.setHeapStart(sAddrHighest);
-  }
+    if (map.getHeapStart() <= 0 && sAddrHighest > 0) {
+      System.err.printf("Warning: Unable to parse _end symbol. I'm guessing that heap starts at 0x%05x\n", sAddrHighest);
+      map.setHeapStart(sAddrHighest);
+    }
 
     return map;
   }
@@ -530,26 +520,24 @@ public class ELF {
     }
   }
 
-
   public void setPos(int pos) {
     this.pos = pos;
-}
+  }
 
-public int getPos() {
+  public int getPos() {
     return pos;
-}
+  }
 
+  private static class FileInfo {
+      public final String name;
+      public final int start;
+      public final int end;
 
-class FileInfo {
-    String name;
-    int start;
-    int end;
-
-    FileInfo(String name, int start, int end) {
-      this.name = name;
-      this.start = start;
-      this.end = end;
-    }
+      FileInfo(String name, int start, int end) {
+          this.name = name;
+          this.start = start;
+          this.end = end;
+      }
 
   }
 
diff --git a/se/sics/mspsim/util/MapTable.java b/se/sics/mspsim/util/MapTable.java
index 9fa039c..e7b0a7e 100644
--- a/se/sics/mspsim/util/MapTable.java
+++ b/se/sics/mspsim/util/MapTable.java
@@ -248,10 +248,18 @@ public class MapTable {
     return -1;
   }
 
+  public int getStackStart() {
+      return stackStartAddress;
+  }
+
   public void setStackStart(int start) {
     stackStartAddress = start;
   }
 
+  public int getHeapStart() {
+      return heapStartAddress;
+  }
+
   public void setHeapStart(int start) {
     heapStartAddress = start;
   }