diff --git a/src/com/bytezone/diskbrowser/disk/Nibblizer.java b/src/com/bytezone/diskbrowser/disk/Nibblizer.java
index 407b891..fdad76a 100644
--- a/src/com/bytezone/diskbrowser/disk/Nibblizer.java
+++ b/src/com/bytezone/diskbrowser/disk/Nibblizer.java
@@ -134,7 +134,6 @@ public class Nibblizer
       if (ptr < 0)
       {
         System.out.printf ("Track: %02X - Address prologue not found%n", trackNo);
-        //        System.out.println (HexFormatter.format (buffer));
         return false;
       }
       AddressField addressField = getAddressField (buffer, ptr);
@@ -174,10 +173,10 @@ public class Nibblizer
         return false;
       }
 
-      int offset = addressField.track * TRACK_SIZE
+      int o = addressField.track * TRACK_SIZE
           + interleave[DOS][addressField.sector] * BLOCK_SIZE;
 
-      System.arraycopy (dataField.dataBuffer, 0, diskBuffer, offset, BLOCK_SIZE);
+      System.arraycopy (dataField.dataBuffer, 0, diskBuffer, o, BLOCK_SIZE);
 
       if (++totalSectors == 16)
         break;
diff --git a/src/com/bytezone/diskbrowser/disk/WozDisk.java b/src/com/bytezone/diskbrowser/disk/WozDisk.java
index 6055068..eca401c 100644
--- a/src/com/bytezone/diskbrowser/disk/WozDisk.java
+++ b/src/com/bytezone/diskbrowser/disk/WozDisk.java
@@ -5,6 +5,8 @@ import java.io.File;
 import java.io.FileInputStream;
 import java.io.IOException;
 
+import com.bytezone.diskbrowser.utilities.Utility;
+
 public class WozDisk
 {
   private static final int TRK_SIZE = 0x1A00;
@@ -27,97 +29,95 @@ public class WozDisk
   {
     this.file = f;
     Nibblizer nibbler = new Nibblizer (f);
-
-    byte[] id = new byte[8];
-    byte[] checksum = new byte[4];
-    byte[] trackBuffer = new byte[TRK_SIZE];
-    byte[] infoBuffer = new byte[INFO_SIZE];
-    byte[] tmapBuffer = new byte[TMAP_SIZE];
+    byte[] buffer = null;
 
     try
     {
       BufferedInputStream in = new BufferedInputStream (new FileInputStream (file));
-      in.read (id);
-      assert matches (id, header);
-      in.read (checksum);
-
-      read: while (in.available () > 8)
-      {
-        String chunkId = readString (in, 4);
-        int chunkSize = readInt (in, 4);
-
-        if ("INFO".equals (chunkId))
-        {
-          if (debug)
-          {
-            in.read (infoBuffer);
-            System.out.printf ("Version ........... %02X%n", infoBuffer[0]);
-            System.out.printf ("Disk type ......... %02X%n", infoBuffer[1]);
-            System.out.printf ("Write protected ... %02X%n", infoBuffer[2]);
-            System.out.printf ("Synchronised ...... %02X%n", infoBuffer[3]);
-            System.out.printf ("Cleaned ........... %02X%n", infoBuffer[4]);
-            System.out.printf ("Creator ........... %s%n%n",
-                new String (infoBuffer, 5, 32));
-          }
-          else
-            in.skip (infoBuffer.length);
-        }
-        else if ("TMAP".equals (chunkId))
-        {
-          if (debug)
-          {
-            in.read (tmapBuffer);
-            int ptr = 0;
-            for (int track = 0; track < 40; track++)
-            {
-              for (int qtr = 0; qtr < 4; qtr++)
-                System.out.printf ("%02X ", tmapBuffer[ptr++]);
-              System.out.println ();
-            }
-            System.out.println ();
-          }
-          else
-            in.skip (tmapBuffer.length);
-        }
-        else if ("TRKS".equals (chunkId))
-        {
-          int tracks = chunkSize / TRK_SIZE;
-          for (int track = 0; track < tracks; track++)
-          {
-            int bytesRead = in.read (trackBuffer);
-            assert bytesRead == TRK_SIZE;
-            int bytesUsed = readInt (trackBuffer, DATA_SIZE, 2);
-            int bitCount = readInt (trackBuffer, DATA_SIZE + 2, 2);
-
-            byte[] trackData = new byte[bytesUsed];
-            readTrack (trackBuffer, trackData, bytesUsed);
-            if (!nibbler.processTrack (track, trackData, diskBuffer))
-            {
-              System.out.println ("Nibblizer failure");
-              //              System.out.println (HexFormatter.format (trackBuffer, 0, trackBuffer.length,
-              //                  TRK_SIZE * track + 256));
-              //              System.out.println ();
-              break read;
-            }
-          }
-        }
-        else if ("META".equals (chunkId))
-        {
-          System.out.printf ("[%s]  %08X%n", chunkId, chunkSize);
-          skip (in, chunkSize);
-        }
-        else
-        {
-          System.out.printf ("Unknown %08X%n", chunkSize);
-          skip (in, chunkSize);
-        }
-      }
+      buffer = in.readAllBytes ();
       in.close ();
     }
     catch (IOException e)
     {
       e.printStackTrace ();
-      System.exit (1);
+      return;
+    }
+
+    assert matches (header, buffer);
+
+    int cs1 = readInt (buffer, 8, 4);
+    int cs2 = Utility.crc32 (buffer, 12, 256 - 12 + 35 * 6656);
+    if (cs1 != cs2)
+    {
+      System.out.printf ("Checksum: %08X%n", cs1);
+      System.out.printf ("Calculat: %08X%n", cs2);
+    }
+
+    int ptr = 12;
+    read: while (ptr < buffer.length)
+    {
+      String chunkId = readString (buffer, ptr, 4);
+      ptr += 4;
+      int chunkSize = readInt (buffer, ptr, 4);
+      ptr += 4;
+
+      if ("INFO".equals (chunkId))
+      {
+        if (debug)
+        {
+          System.out.printf ("Version ........... %02X%n", buffer[ptr]);
+          System.out.printf ("Disk type ......... %02X%n", buffer[ptr + 1]);
+          System.out.printf ("Write protected ... %02X%n", buffer[ptr + 2]);
+          System.out.printf ("Synchronised ...... %02X%n", buffer[ptr + 3]);
+          System.out.printf ("Cleaned ........... %02X%n", buffer[ptr + 4]);
+          System.out.printf ("Creator ........... %s%n%n",
+              new String (buffer, ptr + 5, 32));
+        }
+        ptr += INFO_SIZE;
+      }
+      else if ("TMAP".equals (chunkId))
+      {
+        if (debug)
+        {
+          for (int track = 0; track < 40; track++)
+          {
+            for (int qtr = 0; qtr < 4; qtr++)
+              System.out.printf ("%02X ", buffer[ptr++]);
+            System.out.println ();
+          }
+          System.out.println ();
+        }
+        else
+          ptr += TMAP_SIZE;
+      }
+      else if ("TRKS".equals (chunkId))
+      {
+        int tracks = chunkSize / TRK_SIZE;
+        for (int track = 0; track < tracks; track++)
+        {
+          int bytesUsed = readInt (buffer, ptr + DATA_SIZE, 2);
+          int bitCount = readInt (buffer, ptr + DATA_SIZE + 2, 2);
+
+          byte[] trackData = new byte[bytesUsed];
+          readTrack (buffer, ptr, trackData, bytesUsed);
+          if (!nibbler.processTrack (track, trackData, diskBuffer))
+          {
+            System.out.println ("Nibblizer failure");
+            break read;
+          }
+          ptr += TRK_SIZE;
+        }
+      }
+      else if ("META".equals (chunkId))
+      {
+        System.out.printf ("[%s]  %08X%n", chunkId, chunkSize);
+        ptr += chunkSize;
+      }
+      else
+      {
+        System.out.printf ("Unknown %08X%n", chunkSize);
+        ptr += chunkSize;
+      }
     }
   }
 
@@ -135,11 +135,11 @@ public class WozDisk
   // readString
   // ---------------------------------------------------------------------------------//
 
-  private String readString (BufferedInputStream file, int size) throws IOException
+  private String readString (byte[] buffer, int offset, int length)
   {
-    byte[] bytes = new byte[size];
-    file.read (bytes);
-    return new String (bytes);
+    //    byte[] bytes = new byte[size];
+    //    file.read (bytes);
+    return new String (buffer, offset, length);
   }
 
   // ---------------------------------------------------------------------------------//
@@ -162,12 +162,12 @@ public class WozDisk
   // readInt
   // ---------------------------------------------------------------------------------//
 
-  private int readInt (BufferedInputStream file, int size) throws IOException
-  {
-    byte[] buffer = new byte[size];
-    file.read (buffer);
-    return readInt (buffer, 0, size);
-  }
+  //  private int readInt (BufferedInputStream file, int size) throws IOException
+  //  {
+  //    byte[] buffer = new byte[size];
+  //    file.read (buffer);
+  //    return readInt (buffer, 0, size);
+  //  }
 
   // ---------------------------------------------------------------------------------//
   // matches
@@ -185,13 +185,13 @@ public class WozDisk
   // readTrack
   // ---------------------------------------------------------------------------------//
 
-  private void readTrack (byte[] buffer, byte[] trackData, int bytesUsed)
+  private void readTrack (byte[] buffer, int offset, byte[] trackData, int bytesUsed)
   {
     //    int consecutiveZeros = 0;
     int value = 0;
     int ptr = 0;
 
-    for (int i = 0; i < bytesUsed; i++)
+    for (int i = offset; i < offset + bytesUsed; i++)
     {
       int b = buffer[i] & 0xFF;
       for (int mask = 0x80; mask > 0; mask >>>= 1)
diff --git a/src/com/bytezone/diskbrowser/utilities/Utility.java b/src/com/bytezone/diskbrowser/utilities/Utility.java
index 6a9b257..de730ea 100644
--- a/src/com/bytezone/diskbrowser/utilities/Utility.java
+++ b/src/com/bytezone/diskbrowser/utilities/Utility.java
@@ -94,15 +94,16 @@ public class Utility
     return suffixes.contains (getSuffix (filename));
   }
 
-  public int crc32 (byte[] buffer, int size)
+  public static int crc32 (byte[] buffer, int offset, int length)
   {
-    int crc = ~0;         // one's complement
+    int crc = 0xFFFFFFFF;         // one's complement
 
-    for (int i = 0; i < size; i++)
+    for (int i = offset; i < offset + length; i++)
       crc = crc32_tab[(crc ^ buffer[i]) & 0xFF] ^ (crc >>> 8);
 
-    return ~crc;          // one's complement
+    return ~crc;                 // one's complement
   }
+
   static int[] crc32_tab =
       { 0x00000000, 0x77073096, 0xee0e612c, 0x990951ba, 0x076dc419, 0x706af48f,
         0xe963a535, 0x9e6495a3, 0x0edb8832, 0x79dcb8a4, 0xe0d5e91e, 0x97d2d988,