rewrote the nibble routines

src/com/bytezone/diskbrowser/cpm/CPMDisk.java

@@ -24,6 +24,7 @@ public class CPMDisk extends AbstractFormattedDisk
   public final SectorType macSector = new SectorType ("MAC", Color.green);
 
   private int version;      // http://www.seasip.info/Cpm/format22.html
+  //                        // http://www.seasip.info/Cpm/format31.html
 
   public CPMDisk (Disk disk)
   {

src/com/bytezone/diskbrowser/disk/AppleDisk.java

@@ -231,30 +231,16 @@ public class AppleDisk implements Disk
     this.tracks = tracks;
     this.sectors = sectors;
     file = disk.file;
+    diskBuffer = disk.diskBuffer;
 
     if (sectors == 13)
     {
       trackSize = 0xD00;
       sectorSize = 256;
-      diskBuffer = new byte[116480];
-
-      int ptr = 0;
-      for (int track = 0; track < 35; track++)
-      {
-        for (int sector = 0; sector < 13; sector++)
-        {
-          int ptr2 = track * 0xD00 + sector * 0x100;
-          System.arraycopy (disk.diskBuffer, ptr, diskBuffer, ptr2, 0x100);
-          //          System.out.printf ("Copying %04X -> %04X%n", ptr, ptr2);
-          ptr += 0x100;
-        }
-        ptr += 0x300;       // skip 3 sectors
-      }
     }
     else
     {
-      trackSize = 4096;
-      diskBuffer = disk.diskBuffer;
+      trackSize = 0x1000;
       sectorSize = trackSize / sectors;
     }
 

src/com/bytezone/diskbrowser/disk/ByteTranslator.java

@@ -0,0 +1,8 @@
+package com.bytezone.diskbrowser.disk;
+
+public abstract class ByteTranslator
+{
+  abstract byte encode (byte b);
+
+  abstract byte decode (byte b) throws DiskNibbleException;
+}

src/com/bytezone/diskbrowser/disk/ByteTranslator5and3.java

@@ -0,0 +1,68 @@
+package com.bytezone.diskbrowser.disk;
+
+public class ByteTranslator5and3 extends ByteTranslator
+{
+  // 32 valid bytes that can be stored on a disk (plus 0xAA and 0xD5)
+  private static byte[] writeTranslateTable5and3 =
+      { (byte) 0xAB, (byte) 0xAD, (byte) 0xAE, (byte) 0xAF, (byte) 0xB5, (byte) 0xB6,
+        (byte) 0xB7, (byte) 0xBA, (byte) 0xBB, (byte) 0xBD, (byte) 0xBE, (byte) 0xBF,
+        (byte) 0xD6, (byte) 0xD7, (byte) 0xDA, (byte) 0xDB, //
+        (byte) 0xDD, (byte) 0xDE, (byte) 0xDF, (byte) 0xEA, (byte) 0xEB, (byte) 0xED,
+        (byte) 0xEE, (byte) 0xEF, (byte) 0xF5, (byte) 0xF6, (byte) 0xF7, (byte) 0xFA,
+        (byte) 0xFB, (byte) 0xFD, (byte) 0xFE, (byte) 0xFF };
+
+  private static byte[] readTranslateTable5and3 = new byte[85];   // skip first 171 blanks
+  private static boolean debug = false;
+
+  static
+  {
+    for (int i = 0; i < writeTranslateTable5and3.length; i++)
+    {
+      int j = (writeTranslateTable5and3[i] & 0xFF) - 0xAB;   // skip first 171 blanks
+      readTranslateTable5and3[j] = (byte) (i + 1);           // offset by 1 to avoid zero
+      if (debug)
+        System.out.printf ("%02X  %02X  %02X%n", i, writeTranslateTable5and3[i], j);
+    }
+    if (debug)
+      for (int j = 0; j < readTranslateTable5and3.length; j++)
+      {
+        int target = readTranslateTable5and3[j] - 1;
+        if (target >= 0)
+        {
+          int value = writeTranslateTable5and3[target] & 0xFF;
+          System.out.printf ("%02X -> %02X%n", j, value);
+        }
+        else
+          System.out.printf ("%02X%n", j);
+      }
+  }
+
+  // ---------------------------------------------------------------------------------//
+  // encode
+  // ---------------------------------------------------------------------------------//
+
+  @Override
+  byte encode (byte b)
+  {
+    return 0;
+  }
+
+  // ---------------------------------------------------------------------------------//
+  // decode
+  // ---------------------------------------------------------------------------------//
+
+  @Override
+  byte decode (byte b) throws DiskNibbleException
+  {
+    int val = (b & 0xFF) - 0xAB;                              // 0 - 84
+    //    assert val >= 0 && val <= 84 : "Val: " + val;
+    if (val < 0 || val > 84)
+      throw new DiskNibbleException ("Val: " + val);
+    byte trans = (byte) (readTranslateTable5and3[val] - 1);   // 0 - 31  (5 bits)
+    //    assert trans >= 0 && trans <= 31 : "Trans: " + trans;
+    if (trans < 0 || trans > 31)
+      throw new DiskNibbleException ("Trans: " + trans);
+    return (byte) (trans << 3);                               // left justify 5 bits
+  }
+
+}

src/com/bytezone/diskbrowser/disk/ByteTranslator6and2.java

@@ -0,0 +1,50 @@
+package com.bytezone.diskbrowser.disk;
+
+public class ByteTranslator6and2 extends ByteTranslator
+{
+  // 64 valid bytes that can be stored on a disk (plus 0xAA and 0xD5)
+  private static byte[] writeTranslateTable6and2 =
+      { (byte) 0x96, (byte) 0x97, (byte) 0x9A, (byte) 0x9B, (byte) 0x9D, (byte) 0x9E,
+        (byte) 0x9F, (byte) 0xA6, (byte) 0xA7, (byte) 0xAB, (byte) 0xAC, (byte) 0xAD,
+        (byte) 0xAE, (byte) 0xAF, (byte) 0xB2, (byte) 0xB3, //
+        (byte) 0xB4, (byte) 0xB5, (byte) 0xB6, (byte) 0xB7, (byte) 0xB9, (byte) 0xBA,
+        (byte) 0xBB, (byte) 0xBC, (byte) 0xBD, (byte) 0xBE, (byte) 0xBF, (byte) 0xCB,
+        (byte) 0xCD, (byte) 0xCE, (byte) 0xCF, (byte) 0xD3, //
+        (byte) 0xD6, (byte) 0xD7, (byte) 0xD9, (byte) 0xDA, (byte) 0xDB, (byte) 0xDC,
+        (byte) 0xDD, (byte) 0xDE, (byte) 0xDF, (byte) 0xE5, (byte) 0xE6, (byte) 0xE7,
+        (byte) 0xE9, (byte) 0xEA, (byte) 0xEB, (byte) 0xEC, //
+        (byte) 0xED, (byte) 0xEE, (byte) 0xEF, (byte) 0xF2, (byte) 0xF3, (byte) 0xF4,
+        (byte) 0xF5, (byte) 0xF6, (byte) 0xF7, (byte) 0xF9, (byte) 0xFA, (byte) 0xFB,
+        (byte) 0xFC, (byte) 0xFD, (byte) 0xFE, (byte) 0xFF };
+
+  private static byte[] readTranslateTable6and2 = new byte[106];  // skip first 150 blanks
+
+  static
+  {
+    for (int i = 0; i < writeTranslateTable6and2.length; i++)
+    {
+      int j = (writeTranslateTable6and2[i] & 0xFF) - 0x96;   // skip first 150 blanks
+      readTranslateTable6and2[j] = (byte) (i + 1);           // offset by 1 to avoid zero
+    }
+  }
+
+  @Override
+  byte encode (byte b)
+  {
+    return writeTranslateTable6and2[(b & 0xFC) / 4];
+  }
+
+  @Override
+  byte decode (byte b) throws DiskNibbleException
+  {
+    int val = (b & 0xFF) - 0x96;                              // 0 - 105
+    //    assert val >= 0 && val <= 105 : "Val: " + val;
+    if (val < 0 || val > 105)
+      throw new DiskNibbleException ("Val: " + val);
+    byte trans = (byte) (readTranslateTable6and2[val] - 1);   // 0 - 63  (6 bits)
+    //    assert trans >= 0 && trans <= 63 : "Trans: " + trans;
+    if (trans < 0 || trans > 63)
+      throw new DiskNibbleException ("Trans: " + trans);
+    return (byte) (trans << 2);                               // left justify 6 bits
+  }
+}

src/com/bytezone/diskbrowser/disk/DiskAddressField.java

@@ -0,0 +1,40 @@
+package com.bytezone.diskbrowser.disk;
+
+class DiskAddressField
+{
+  int track, sector, volume, checksum;
+
+  // ---------------------------------------------------------------------------------//
+  // constructor
+  // ---------------------------------------------------------------------------------//
+
+  DiskAddressField (byte[] buffer, int offset)
+  {
+    volume = decode4and4 (buffer, offset);
+    track = decode4and4 (buffer, offset + 2);
+    sector = decode4and4 (buffer, offset + 4);
+    checksum = decode4and4 (buffer, offset + 6);
+  }
+
+  // ---------------------------------------------------------------------------------//
+  // decode4and4
+  // ---------------------------------------------------------------------------------//
+
+  int decode4and4 (byte[] buffer, int offset)
+  {
+    int odds = ((buffer[offset] & 0xFF) << 1) + 1;
+    int evens = buffer[offset + 1] & 0xFF;
+    return odds & evens;
+  }
+
+  // ---------------------------------------------------------------------------------//
+  // toString
+  // ---------------------------------------------------------------------------------//
+
+  @Override
+  public String toString ()
+  {
+    return String.format ("[volume: %02X, track: %02X, sector: %02X, checksum: %02X]",
+        volume, track, sector, checksum);
+  }
+}

src/com/bytezone/diskbrowser/disk/DiskFactory.java

@@ -232,7 +232,7 @@ public class DiskFactory
       try
       {
         WozDisk wozDisk = new WozDisk (file);
-        if (wozDisk.sectorsPerTrack == 13)
+        if (wozDisk.getSectorsPerTrack () == 13)
         {
           AppleDisk appleDisk = new AppleDisk (wozDisk, 35, 13);
           disk = checkDos (appleDisk);
@@ -248,7 +248,8 @@ public class DiskFactory
       }
       catch (Exception e)
       {
-        System.out.println (e);
+        //        System.out.println (e);
+        e.printStackTrace ();
         return null;
       }
     }

src/com/bytezone/diskbrowser/disk/DiskNibbleException.java

@@ -0,0 +1,17 @@
+package com.bytezone.diskbrowser.disk;
+
+public class DiskNibbleException extends Exception
+{
+  String message;
+
+  public DiskNibbleException (String message)
+  {
+    this.message = message;
+  }
+
+  @Override
+  public String toString ()
+  {
+    return message;
+  }
+}

src/com/bytezone/diskbrowser/disk/DiskReader.java

@@ -0,0 +1,33 @@
+package com.bytezone.diskbrowser.disk;
+
+import com.bytezone.diskbrowser.disk.MC3470.DiskSector;
+
+public abstract class DiskReader
+{
+  static final int BLOCK_SIZE = 256;
+  static final byte[] dataPrologue = { (byte) 0xD5, (byte) 0xAA, (byte) 0xAD };
+
+  int sectorsPerTrack;
+  boolean debug = false;
+
+  // ---------------------------------------------------------------------------------//
+  // constructor
+  // ---------------------------------------------------------------------------------//
+
+  DiskReader (int sectorsPerTrack)
+  {
+    this.sectorsPerTrack = sectorsPerTrack;
+  }
+
+  // ---------------------------------------------------------------------------------//
+  // abstract functions
+  // ---------------------------------------------------------------------------------//
+
+  abstract byte[] decodeSector (byte[] buffer, int ptr);
+
+  abstract byte[] encodeSector (byte[] buffer);
+
+  abstract void storeBuffer (DiskSector diskSector, byte[] diskBuffer);
+
+  abstract int expectedDataSize ();
+}

src/com/bytezone/diskbrowser/disk/DiskReader13Sector.java

@@ -0,0 +1,122 @@
+package com.bytezone.diskbrowser.disk;
+
+import com.bytezone.diskbrowser.disk.MC3470.DiskSector;
+
+public class DiskReader13Sector extends DiskReader
+{
+  private static final int RAW_BUFFER_SIZE_DOS_32 = 410;
+  private static final int BUFFER_WITH_CHECKSUM_SIZE_DOS_32 = RAW_BUFFER_SIZE_DOS_32 + 1;
+
+  private final byte[] decodeDos32a = new byte[BUFFER_WITH_CHECKSUM_SIZE_DOS_32];
+  private final byte[] decodeDos32b = new byte[RAW_BUFFER_SIZE_DOS_32];
+
+  private final ByteTranslator byteTranslator53 = new ByteTranslator5and3 ();
+
+  // ---------------------------------------------------------------------------------//
+  // constructor
+  // ---------------------------------------------------------------------------------//
+
+  DiskReader13Sector ()
+  {
+    super (13);
+  }
+
+  // ---------------------------------------------------------------------------------//
+  // decodeSector
+  // ---------------------------------------------------------------------------------//
+
+  @Override
+  byte[] decodeSector (byte[] buffer, int offset)
+  {
+    byte[] decodedBuffer = new byte[BLOCK_SIZE];
+
+    try
+    {
+      // convert legal disk values to actual 5 bit values
+      for (int i = 0; i < BUFFER_WITH_CHECKSUM_SIZE_DOS_32; i++)        // 411 bytes
+        decodeDos32a[i] = byteTranslator53.decode (buffer[offset++]);
+
+      // reconstruct 410 bytes each with 5 bits
+      byte chk = 0;
+      int ptr = 0;
+      for (int i = 409; i >= 256; i--)                                  // 154 bytes
+        chk = decodeDos32b[i] = (byte) (decodeDos32a[ptr++] ^ chk);
+      for (int i = 0; i < 256; i++)                                     // 256 bytes
+        chk = decodeDos32b[i] = (byte) (decodeDos32a[ptr++] ^ chk);
+      if ((chk ^ decodeDos32a[ptr]) != 0)
+        throw new DiskNibbleException ("Checksum failed");
+
+      // rearrange 410 bytes into 256
+      byte[] k = new byte[8];
+      final int[] lines = { 0, 51, 102, 153, 204, 256, 307, 358 };   // 255 is skipped
+
+      // process 8 disk bytes at a time, giving 5 valid bytes
+      // do this 51 times, giving 255 bytes
+      ptr = 0;
+      for (int i = 50; i >= 0; i--)
+      {
+        for (int j = 0; j < 8; j++)
+          k[j] = decodeDos32b[i + lines[j]];
+
+        k[0] |= (k[5] & 0xE0) >>> 5;
+        k[1] |= (k[6] & 0xE0) >>> 5;
+        k[2] |= (k[7] & 0xE0) >>> 5;
+
+        k[3] |= (k[5] & 0x10) >>> 2;
+        k[3] |= (k[6] & 0x10) >>> 3;
+        k[3] |= (k[7] & 0x10) >>> 4;
+
+        k[4] |= (k[5] & 0x08) >>> 1;
+        k[4] |= (k[6] & 0x08) >>> 2;
+        k[4] |= (k[7] & 0x08) >>> 3;
+
+        for (int j = 0; j < 5; j++)
+          decodedBuffer[ptr++] = k[j];
+      }
+
+      // add last byte
+      decodedBuffer[ptr] =
+          (byte) (decodeDos32b[255] | ((decodeDos32b[409] & 0x3F) >>> 3));
+    }
+    catch (Exception e)
+    {
+      System.out.println (e);
+    }
+
+    return decodedBuffer;
+  }
+
+  // ---------------------------------------------------------------------------------//
+  // encodeSector
+  // ---------------------------------------------------------------------------------//
+
+  @Override
+  byte[] encodeSector (byte[] buffer)
+  {
+    System.out.println ("encodeSector() not written");
+    return null;
+  }
+
+  // ---------------------------------------------------------------------------------//
+  // storeBuffer
+  // ---------------------------------------------------------------------------------//
+
+  @Override
+  void storeBuffer (DiskSector diskSector, byte[] diskBuffer)
+  {
+    DiskAddressField addressField = diskSector.addressField;
+    byte[] sectorBuffer = diskSector.buffer;
+    int offset = addressField.track * 0x0D00 + addressField.sector * 256;
+    System.arraycopy (sectorBuffer, 0, diskBuffer, offset, 256);
+  }
+
+  // ---------------------------------------------------------------------------------//
+  // expectedDataSize
+  // ---------------------------------------------------------------------------------//
+
+  @Override
+  int expectedDataSize ()
+  {
+    return 411;
+  }
+}

src/com/bytezone/diskbrowser/disk/DiskReader16Sector.java

@@ -0,0 +1,163 @@
+package com.bytezone.diskbrowser.disk;
+
+import com.bytezone.diskbrowser.disk.MC3470.DiskSector;
+
+public class DiskReader16Sector extends DiskReader
+{
+  private static final int RAW_BUFFER_SIZE_DOS_33 = 342;
+  private static final int BUFFER_WITH_CHECKSUM_SIZE_DOS_33 = RAW_BUFFER_SIZE_DOS_33 + 1;
+
+  private final byte[] decodeDos33a = new byte[BUFFER_WITH_CHECKSUM_SIZE_DOS_33];
+  private final byte[] decodeDos33b = new byte[RAW_BUFFER_SIZE_DOS_33];
+
+  private final byte[] encodeDos33a = new byte[RAW_BUFFER_SIZE_DOS_33];
+  private final byte[] encodeDos33b = new byte[BUFFER_WITH_CHECKSUM_SIZE_DOS_33];
+
+  private final ByteTranslator byteTranslator62 = new ByteTranslator6and2 ();
+
+  private static int[] interleave =
+      { 0, 8, 1, 9, 2, 10, 3, 11, 4, 12, 5, 13, 6, 14, 7, 15 };
+
+  // ---------------------------------------------------------------------------------//
+  // constructor
+  // ---------------------------------------------------------------------------------//
+
+  DiskReader16Sector ()
+  {
+    super (16);
+  }
+
+  // ---------------------------------------------------------------------------------//
+  // decodeSector
+  // ---------------------------------------------------------------------------------//
+
+  @Override
+  byte[] decodeSector (byte[] buffer, int offset)
+  {
+    // rearrange 342 bytes into 256
+    byte[] decodedBuffer = new byte[BLOCK_SIZE];                      // 256 bytes
+
+    try
+    {
+      if (offset + BUFFER_WITH_CHECKSUM_SIZE_DOS_33 >= buffer.length)
+        throw new DiskNibbleException (
+            String.format ("Buffer not long enough (need %d, found %d)",
+                BUFFER_WITH_CHECKSUM_SIZE_DOS_33, buffer.length - offset));
+
+      // convert legal disk values to actual 6 bit values
+      for (int i = 0; i < BUFFER_WITH_CHECKSUM_SIZE_DOS_33; i++)      // 343 bytes
+      {
+        if (offset == buffer.length)
+          offset = 0;
+        decodeDos33a[i] = byteTranslator62.decode (buffer[offset++]);
+      }
+
+      // reconstruct 342 bytes each with 6 bits
+      byte chk = 0;
+      for (int i = decodeDos33b.length - 1; i >= 0; i--)              // 342 bytes
+        chk = decodeDos33b[i] = (byte) (decodeDos33a[i + 1] ^ chk);
+      if ((chk ^ decodeDos33a[0]) != 0)
+        throw new DiskNibbleException ("Checksum failed");
+
+      // move 6 bits into place
+      for (int i = 0; i < BLOCK_SIZE; i++)
+        decodedBuffer[i] = decodeDos33b[i + 86];
+
+      // reattach each byte's last 2 bits
+      for (int i = 0, j = 86, k = 172; i < 86; i++, j++, k++)
+      {
+        byte val = decodeDos33b[i];
+
+        decodedBuffer[i] |= reverse ((val & 0x0C) >> 2);
+        decodedBuffer[j] |= reverse ((val & 0x30) >> 4);
+
+        if (k < BLOCK_SIZE)
+          decodedBuffer[k] |= reverse ((val & 0xC0) >> 6);
+      }
+    }
+    catch (Exception e)
+    {
+      System.out.println (e);
+    }
+
+    return decodedBuffer;
+  }
+
+  // ---------------------------------------------------------------------------------//
+  // encodeSector
+  // ---------------------------------------------------------------------------------//
+
+  // convert 256 data bytes into 342 translated bytes plus a checksum
+  @Override
+  byte[] encodeSector (byte[] buffer)
+  {
+    byte[] encodedBuffer = new byte[BUFFER_WITH_CHECKSUM_SIZE_DOS_33];
+
+    // move data buffer down to make room for the 86 extra bytes
+    for (int i = 0; i < BLOCK_SIZE; i++)
+      encodeDos33a[i + 86] = buffer[i];
+
+    // build extra 86 bytes from the bits stripped from the data bytes
+    for (int i = 0; i < 86; i++)
+    {
+      int b1 = reverse (buffer[i] & 0x03) << 2;
+      int b2 = reverse (buffer[i + 86] & 0x03) << 4;
+
+      if (i < 84)
+      {
+        int b3 = reverse (buffer[i + 172] & 0x03) << 6;
+        encodeDos33a[i] = (byte) (b1 | b2 | b3);
+      }
+      else
+        encodeDos33a[i] = (byte) (b1 | b2);
+    }
+
+    // convert into checksum bytes
+    byte checksum = 0;
+    for (int i = 0; i < RAW_BUFFER_SIZE_DOS_33; i++)
+    {
+      encodeDos33b[i] = (byte) (checksum ^ encodeDos33a[i]);
+      checksum = encodeDos33a[i];
+    }
+    encodeDos33b[RAW_BUFFER_SIZE_DOS_33] = checksum;        // add checksum to the end
+
+    // remove two bits and convert to translated bytes
+    for (int i = 0; i < BUFFER_WITH_CHECKSUM_SIZE_DOS_33; i++)
+      encodedBuffer[i] = byteTranslator62.encode (encodeDos33b[i]);
+
+    return encodedBuffer;
+  }
+
+  // ---------------------------------------------------------------------------------//
+  // reverse
+  // ---------------------------------------------------------------------------------//
+
+  // reverse 2 bits - 0 <= bits <= 3
+  private static int reverse (int bits)
+  {
+    return bits == 1 ? 2 : bits == 2 ? 1 : bits;
+  }
+
+  // ---------------------------------------------------------------------------------//
+  // storeBuffer
+  // ---------------------------------------------------------------------------------//
+
+  @Override
+  void storeBuffer (DiskSector diskSector, byte[] diskBuffer)
+  {
+    DiskAddressField addressField = diskSector.addressField;
+    byte[] sectorBuffer = diskSector.buffer;
+    int offset = addressField.track * 0x1000 + interleave[addressField.sector] * 256;
+    System.arraycopy (sectorBuffer, 0, diskBuffer, offset, 256);
+  }
+
+  // ---------------------------------------------------------------------------------//
+  // expectedDataSize
+  // ---------------------------------------------------------------------------------//
+
+  @Override
+  int expectedDataSize ()
+  {
+    return 343;
+  }
+}

src/com/bytezone/diskbrowser/disk/MC3470.java

@@ -0,0 +1,229 @@
+package com.bytezone.diskbrowser.disk;
+
+import java.util.ArrayList;
+import java.util.List;
+
+class MC3470
+{
+  private final boolean debug = false;
+
+  private final byte[] dataBuffer = new byte[411];
+  int dataPtr = 0;
+
+  private final List<DiskSector> diskSectors = new ArrayList<> ();
+  DiskReader diskReader;
+
+  State currentState;
+  DiskSector currentDiskSector;
+  int expectedDataSize;
+
+  DiskReader diskReader16 = new DiskReader16Sector ();
+  DiskReader diskReader13 = new DiskReader13Sector ();
+
+  enum State
+  {
+    ADDRESS, DATA, OTHER
+  }
+
+  // ---------------------------------------------------------------------------------//
+  // readTrack
+  // ---------------------------------------------------------------------------------//
+
+  void readTrack (byte[] buffer, int offset, int bytesUsed, int bitCount)
+  {
+    int value = 0;
+
+    final int max = offset + bytesUsed;
+    int totalBits = 0;
+
+    diskSectors.clear ();
+    currentDiskSector = null;
+    currentState = State.OTHER;
+
+    if (debug)
+    {
+      System.out.printf ("%nOffset    : %06X%n", offset);
+      System.out.printf ("Bytes used: %06X%n", bytesUsed);
+    }
+
+    int inPtr = offset;
+    while (inPtr < max)
+    {
+      int b = buffer[inPtr++] & 0xFF;
+      for (int mask = 0x80; mask != 0; mask >>>= 1)
+      {
+        value <<= 1;
+        if ((b & mask) != 0)
+          value |= 1;
+
+        ++totalBits;
+
+        if ((value & 0x80) != 0)                        // is hi-bit set?
+        {
+          dataBuffer[dataPtr++] = (byte) value;
+          checkState (value);
+          value = 0;
+        }
+      }
+      if (inPtr == max && currentState == State.DATA)
+      {
+        System.out.println ("Unfinished business");
+      }
+    }
+
+    //    if (bytesUsed > outputBuffer.length)
+    //    {
+    //      System.out.printf ("Bytes used  %,5d%n", bytesUsed);
+    //      System.out.printf ("Buffer size %,5d%n", outPtr);
+    //    }
+
+    if (value != 0)
+      System.out.printf ("********** Value not used: %01X%n", value);
+  }
+
+  // ---------------------------------------------------------------------------------//
+  // storeSectors
+  // ---------------------------------------------------------------------------------//
+
+  void storeSectors (byte[] diskBuffer)
+  {
+    for (DiskSector diskSector : diskSectors)
+      diskReader.storeBuffer (diskSector, diskBuffer);
+  }
+
+  // ---------------------------------------------------------------------------------//
+  // checkState
+  // ---------------------------------------------------------------------------------//
+
+  private void checkState (int value)
+  {
+    if (value == 0xB5 && isPrologue ())
+    {
+      diskReader = diskReader13;
+      setState (State.ADDRESS);
+    }
+
+    if (value == 0x96 && isPrologue ())
+    {
+      diskReader = diskReader16;
+      setState (State.ADDRESS);
+    }
+
+    if (value == 0xAD && isPrologue ())
+      setState (State.DATA);
+
+    if (value == 0xEB && isEpilogue ())
+      setState (State.OTHER);
+
+    if (dataPtr == expectedDataSize)
+      setState (State.OTHER);
+  }
+
+  // ---------------------------------------------------------------------------------//
+  // setState
+  // ---------------------------------------------------------------------------------//
+
+  private void setState (State newState)
+  {
+    if (currentState == newState && currentState == State.OTHER)
+      return;
+    assert currentState != newState;
+
+    switch (currentState)           // this state is now finished
+    {
+      case ADDRESS:
+        currentDiskSector = new DiskSector (new DiskAddressField (dataBuffer, 0));
+        break;
+
+      case DATA:
+        currentDiskSector.setBuffer (diskReader.decodeSector (dataBuffer, 0));
+        diskSectors.add (currentDiskSector);
+        break;
+
+      case OTHER:
+        break;
+    }
+
+    currentState = newState;
+    dataPtr = 0;                    // start collecting new buffer
+
+    switch (currentState)           // this state is now starting
+    {
+      case ADDRESS:
+        expectedDataSize = 8;
+        break;
+
+      case DATA:
+        expectedDataSize = diskReader.expectedDataSize ();
+        break;
+
+      case OTHER:
+        expectedDataSize = -1;      // unspecified length
+        break;
+    }
+  }
+
+  // ---------------------------------------------------------------------------------//
+  // is13Sector
+  // ---------------------------------------------------------------------------------//
+
+  boolean is13Sector ()
+  {
+    return diskSectors.size () == 13 && diskReader.sectorsPerTrack == 13;
+  }
+
+  // ---------------------------------------------------------------------------------//
+  // is16Sector
+  // ---------------------------------------------------------------------------------//
+
+  boolean is16Sector ()
+  {
+    return diskSectors.size () == 16 && diskReader.sectorsPerTrack == 16;
+  }
+
+  // ---------------------------------------------------------------------------------//
+  // isPrologue
+  // ---------------------------------------------------------------------------------//
+
+  private boolean isPrologue ()
+  {
+    return dataPtr >= 3 && dataBuffer[dataPtr - 3] == (byte) 0xD5
+        && dataBuffer[dataPtr - 2] == (byte) 0xAA;
+  }
+
+  // ---------------------------------------------------------------------------------//
+  // isEpilogue
+  // ---------------------------------------------------------------------------------//
+
+  private boolean isEpilogue ()
+  {
+    return dataPtr >= 3 && dataBuffer[dataPtr - 3] == (byte) 0xDE
+        && dataBuffer[dataPtr - 2] == (byte) 0xAA;
+  }
+
+  // ---------------------------------------------------------------------------------//
+  // DiskSector
+  // ---------------------------------------------------------------------------------//
+
+  class DiskSector
+  {
+    DiskAddressField addressField;
+    byte[] buffer;
+
+    DiskSector (DiskAddressField addressField)
+    {
+      this.addressField = addressField;
+    }
+
+    void setBuffer (byte[] buffer)
+    {
+      this.buffer = buffer;
+    }
+
+    @Override
+    public String toString ()
+    {
+      return addressField.toString ();
+    }
+  }
+}

src/com/bytezone/diskbrowser/disk/Nibblizer.java

@@ -2,6 +2,8 @@ package com.bytezone.diskbrowser.disk;
 
 class Nibblizer
 {
+  // still used by NibDisk and V2dDisk
+
   private static byte[] addressPrologue32 = { (byte) 0xD5, (byte) 0xAA, (byte) 0xB5 };
   private static byte[] addressPrologue33 = { (byte) 0xD5, (byte) 0xAA, (byte) 0x96 };
   private static byte[] dataPrologue = { (byte) 0xD5, (byte) 0xAA, (byte) 0xAD };
@@ -11,53 +13,13 @@ class Nibblizer
       { 0, 8, 1, 9, 2, 10, 3, 11, 4, 12, 5, 13, 6, 14, 7, 15 };
 
   private static final int BLOCK_SIZE = 256;
-  private static final int TRACK_SIZE = 4096;
   private static final int RAW_BUFFER_SIZE_DOS_33 = 342;
   private static final int RAW_BUFFER_SIZE_DOS_32 = 410;
   private static final int BUFFER_WITH_CHECKSUM_SIZE_DOS_33 = RAW_BUFFER_SIZE_DOS_33 + 1;
   private static final int BUFFER_WITH_CHECKSUM_SIZE_DOS_32 = RAW_BUFFER_SIZE_DOS_32 + 1;
 
-  // 32 valid bytes that can be stored on a disk (plus 0xAA and 0xD5)
-  private static byte[] writeTranslateTable5and3 =
-      { (byte) 0xAB, (byte) 0xAD, (byte) 0xAE, (byte) 0xAF, (byte) 0xB5, (byte) 0xB6,
-        (byte) 0xB7, (byte) 0xBA, (byte) 0xBB, (byte) 0xBD, (byte) 0xBE, (byte) 0xBF,
-        (byte) 0xD6, (byte) 0xD7, (byte) 0xDA, (byte) 0xDB, //
-        (byte) 0xDD, (byte) 0xDE, (byte) 0xDF, (byte) 0xEA, (byte) 0xEB, (byte) 0xED,
-        (byte) 0xEE, (byte) 0xEF, (byte) 0xF5, (byte) 0xF6, (byte) 0xF7, (byte) 0xFA,
-        (byte) 0xFB, (byte) 0xFD, (byte) 0xFE, (byte) 0xFF };
-
-  // 64 valid bytes that can be stored on a disk (plus 0xAA and 0xD5)
-  private static byte[] writeTranslateTable6and2 =
-      { (byte) 0x96, (byte) 0x97, (byte) 0x9A, (byte) 0x9B, (byte) 0x9D, (byte) 0x9E,
-        (byte) 0x9F, (byte) 0xA6, (byte) 0xA7, (byte) 0xAB, (byte) 0xAC, (byte) 0xAD,
-        (byte) 0xAE, (byte) 0xAF, (byte) 0xB2, (byte) 0xB3, //
-        (byte) 0xB4, (byte) 0xB5, (byte) 0xB6, (byte) 0xB7, (byte) 0xB9, (byte) 0xBA,
-        (byte) 0xBB, (byte) 0xBC, (byte) 0xBD, (byte) 0xBE, (byte) 0xBF, (byte) 0xCB,
-        (byte) 0xCD, (byte) 0xCE, (byte) 0xCF, (byte) 0xD3, //
-        (byte) 0xD6, (byte) 0xD7, (byte) 0xD9, (byte) 0xDA, (byte) 0xDB, (byte) 0xDC,
-        (byte) 0xDD, (byte) 0xDE, (byte) 0xDF, (byte) 0xE5, (byte) 0xE6, (byte) 0xE7,
-        (byte) 0xE9, (byte) 0xEA, (byte) 0xEB, (byte) 0xEC, //
-        (byte) 0xED, (byte) 0xEE, (byte) 0xEF, (byte) 0xF2, (byte) 0xF3, (byte) 0xF4,
-        (byte) 0xF5, (byte) 0xF6, (byte) 0xF7, (byte) 0xF9, (byte) 0xFA, (byte) 0xFB,
-        (byte) 0xFC, (byte) 0xFD, (byte) 0xFE, (byte) 0xFF };
-
-  private static byte[] readTranslateTable5and3 = new byte[85];   // skip first 171 blanks
-  private static byte[] readTranslateTable6and2 = new byte[106];  // skip first 150 blanks
-
-  static
-  {
-    for (int i = 0; i < writeTranslateTable5and3.length; i++)
-    {
-      int j = (writeTranslateTable5and3[i] & 0xFF) - 0xAB;   // skip first 171 blanks
-      readTranslateTable5and3[j] = (byte) (i + 1);           // offset by 1 to avoid zero
-    }
-
-    for (int i = 0; i < writeTranslateTable6and2.length; i++)
-    {
-      int j = (writeTranslateTable6and2[i] & 0xFF) - 0x96;   // skip first 150 blanks
-      readTranslateTable6and2[j] = (byte) (i + 1);           // offset by 1 to avoid zero
-    }
-  }
+  private final ByteTranslator byteTranslator62 = new ByteTranslator6and2 ();
+  private final ByteTranslator byteTranslator53 = new ByteTranslator5and3 ();
 
   private final byte[] decodeDos33a = new byte[BUFFER_WITH_CHECKSUM_SIZE_DOS_33];
   private final byte[] decodeDos33b = new byte[RAW_BUFFER_SIZE_DOS_33];
@@ -68,52 +30,35 @@ class Nibblizer
   private final byte[] decodeDos32a = new byte[BUFFER_WITH_CHECKSUM_SIZE_DOS_32];
   private final byte[] decodeDos32b = new byte[RAW_BUFFER_SIZE_DOS_32];
 
-  enum DosVersion
-  {
-    DOS_3_2, DOS_3_3
-  }
-
-  private DosVersion currentDosVersion;
-  int sectorsPerTrack;
+  private int sectorsPerTrack;
 
   // ---------------------------------------------------------------------------------//
   // processTrack
   // ---------------------------------------------------------------------------------//
 
-  boolean processTrack (int trackNo, byte[] buffer, byte[] diskBuffer)
+  boolean processTrack (int trackNo, int maxTracks, byte[] buffer, byte[] diskBuffer)
   {
     int ptr = 0;
     int totalSectors = 0;
     boolean[] sectorsFound = new boolean[16];
+    sectorsPerTrack = maxTracks;
 
     try
     {
       while (ptr < buffer.length)
       {
-        int ptr2 = findBytes (buffer, ptr, addressPrologue33);
-        if (ptr2 >= 0)
-        {
-          currentDosVersion = DosVersion.DOS_3_3;
-          sectorsPerTrack = 16;
-        }
+        if (sectorsPerTrack == 13)
+          ptr = findBytes (buffer, ptr, addressPrologue32);
         else
-        {
-          ptr2 = findBytes (buffer, ptr, addressPrologue32);
-          if (ptr2 >= 0)
-          {
-            currentDosVersion = DosVersion.DOS_3_2;
-            sectorsPerTrack = 13;
-          }
-          else
-          {
-            System.out.printf ("Track: %02X/%02X - Address prologue not found%n", trackNo,
-                totalSectors);
-            return false;
-          }
-        }
-        ptr = ptr2;
+          ptr = findBytes (buffer, ptr, addressPrologue33);
 
-        AddressField addressField = getAddressField (buffer, ptr);
+        if (ptr < 0)
+        {
+          System.out.printf ("Track: %02X - Address prologue not found%n", trackNo);
+          return false;
+        }
+
+        AddressField addressField = new AddressField (buffer, ptr);
         if (!addressField.isValid ())
         {
           System.out.printf ("Track: %02X - Invalid address field%n", trackNo);
@@ -145,26 +90,23 @@ class Nibblizer
           return false;
         }
 
-        DataField dataField = getDataField (buffer, ptr);
+        DataField dataField = new DataField (buffer, ptr);
         if (!dataField.isValid ())
         {
           System.out.printf ("Track: %02X - Invalid data field%n", trackNo);
           return false;
         }
 
-        int offset = addressField.track * TRACK_SIZE;
-        if (currentDosVersion == DosVersion.DOS_3_2)
-          offset += addressField.sector * BLOCK_SIZE;
+        int offset;
+        if (sectorsPerTrack == 13)
+          offset = addressField.track * 0x0D00 + addressField.sector * BLOCK_SIZE;
         else
-          offset += interleave[addressField.sector] * BLOCK_SIZE;
+          offset =
+              addressField.track * 0x1000 + interleave[addressField.sector] * BLOCK_SIZE;
 
         System.arraycopy (dataField.dataBuffer, 0, diskBuffer, offset, BLOCK_SIZE);
 
-        ++totalSectors;
-
-        if (currentDosVersion == DosVersion.DOS_3_2 && totalSectors == 13)
-          break;
-        if (currentDosVersion == DosVersion.DOS_3_3 && totalSectors == 16)
+        if (++totalSectors == sectorsPerTrack)
           break;
 
         ptr += dataField.size ();
@@ -175,13 +117,7 @@ class Nibblizer
       e.printStackTrace ();
     }
 
-    if (currentDosVersion == DosVersion.DOS_3_2 && totalSectors != 13)
-    {
-      System.out.printf ("Track: %02X - Sectors found: %02X%n", trackNo, totalSectors);
-      return false;
-    }
-
-    if (currentDosVersion == DosVersion.DOS_3_3 && totalSectors != 16)
+    if (totalSectors != sectorsPerTrack)
     {
       System.out.printf ("Track: %02X - Sectors found: %02X%n", trackNo, totalSectors);
       return false;
@@ -190,24 +126,6 @@ class Nibblizer
     return true;
   }
 
-  // ---------------------------------------------------------------------------------//
-  // getAddressField
-  // ---------------------------------------------------------------------------------//
-
-  private AddressField getAddressField (byte[] buffer, int offset)
-  {
-    return new AddressField (buffer, offset);
-  }
-
-  // ---------------------------------------------------------------------------------//
-  // getDataField
-  // ---------------------------------------------------------------------------------//
-
-  private DataField getDataField (byte[] buffer, int offset)
-  {
-    return new DataField (buffer, offset);
-  }
-
   // ---------------------------------------------------------------------------------//
   // decode4and4
   // ---------------------------------------------------------------------------------//
@@ -225,113 +143,105 @@ class Nibblizer
 
   private byte[] decode5and3 (byte[] buffer, int offset)
   {
-    // convert legal disk values to actual 5 bit values
-    for (int i = 0; i < BUFFER_WITH_CHECKSUM_SIZE_DOS_32; i++)        // 411 bytes
-      decodeDos32a[i] = getByte5and3 (buffer[offset++]);
-
-    // reconstruct 410 bytes each with 5 bits
-    byte chk = 0;
-    int ptr = 0;
-    for (int i = 409; i >= 256; i--)                                  // 154 bytes
-      chk = decodeDos32b[i] = (byte) (decodeDos32a[ptr++] ^ chk);
-    for (int i = 0; i < 256; i++)                                     // 256 bytes
-      chk = decodeDos32b[i] = (byte) (decodeDos32a[ptr++] ^ chk);
-    assert (chk ^ decodeDos32a[ptr]) == 0;
-
     // rearrange 410 bytes into 256
     byte[] decodedBuffer = new byte[BLOCK_SIZE];                      // 256 bytes
-    byte[] k = new byte[8];
-    ptr = 0;
-    int[] lines = { 0, 51, 102, 153, 204, 256, 307, 358 };      // NB 255 is skipped
 
-    // process 8 disk bytes at a time, giving 5 valid bytes
-    // do this 51 times, giving 255 bytes
-    for (int i = 50; i >= 0; i--)
+    try
     {
-      for (int j = 0; j < 8; j++)
-        k[j] = decodeDos32b[i + lines[j]];
+      // convert legal disk values to actual 5 bit values
+      for (int i = 0; i < BUFFER_WITH_CHECKSUM_SIZE_DOS_32; i++)        // 411 bytes
+      {
+        //      System.out.printf ("%,5d  %02X%n", i, buffer[offset]);
+        decodeDos32a[i] = byteTranslator53.decode (buffer[offset++]);
+      }
 
-      k[0] |= (k[5] & 0xE0) >>> 5;
-      k[1] |= (k[6] & 0xE0) >>> 5;
-      k[2] |= (k[7] & 0xE0) >>> 5;
+      // reconstruct 410 bytes each with 5 bits
+      byte chk = 0;
+      int ptr = 0;
+      for (int i = 409; i >= 256; i--)                                  // 154 bytes
+        chk = decodeDos32b[i] = (byte) (decodeDos32a[ptr++] ^ chk);
+      for (int i = 0; i < 256; i++)                                     // 256 bytes
+        chk = decodeDos32b[i] = (byte) (decodeDos32a[ptr++] ^ chk);
+      assert (chk ^ decodeDos32a[ptr]) == 0;
 
-      k[3] |= (k[5] & 0x10) >>> 2;
-      k[3] |= (k[6] & 0x10) >>> 3;
-      k[3] |= (k[7] & 0x10) >>> 4;
+      byte[] k = new byte[8];
+      ptr = 0;
+      final int[] lines = { 0, 51, 102, 153, 204, 256, 307, 358 };      // 255 is skipped
 
-      k[4] |= (k[5] & 0x08) >>> 1;
-      k[4] |= (k[6] & 0x08) >>> 2;
-      k[4] |= (k[7] & 0x08) >>> 3;
+      // process 8 disk bytes at a time, giving 5 valid bytes
+      // do this 51 times, giving 255 bytes
+      for (int i = 50; i >= 0; i--)
+      {
+        for (int j = 0; j < 8; j++)
+          k[j] = decodeDos32b[i + lines[j]];
+
+        k[0] |= (k[5] & 0xE0) >>> 5;
+        k[1] |= (k[6] & 0xE0) >>> 5;
+        k[2] |= (k[7] & 0xE0) >>> 5;
+
+        k[3] |= (k[5] & 0x10) >>> 2;
+        k[3] |= (k[6] & 0x10) >>> 3;
+        k[3] |= (k[7] & 0x10) >>> 4;
+
+        k[4] |= (k[5] & 0x08) >>> 1;
+        k[4] |= (k[6] & 0x08) >>> 2;
+        k[4] |= (k[7] & 0x08) >>> 3;
+
+        for (int j = 0; j < 5; j++)
+          decodedBuffer[ptr++] = k[j];
+      }
+
+      // add last byte
+      decodedBuffer[255] = (byte) (decodeDos32b[255] | (decodeDos32b[409] >>> 3));
+    }
+    catch (Exception e)
+    {
 
-      for (int j = 0; j < 5; j++)
-        decodedBuffer[ptr++] = k[j];
     }
 
-    // add last byte
-    decodedBuffer[255] = (byte) (decodeDos32b[255] | (decodeDos32b[409] >>> 3));
-
     return decodedBuffer;
   }
 
-  // ---------------------------------------------------------------------------------//
-  // getByte5and3
-  // ---------------------------------------------------------------------------------//
-
-  private byte getByte5and3 (byte b)
-  {
-    int val = (b & 0xFF) - 0xAB;                              // 0 - 84
-    assert val >= 0 && val <= 84;
-    byte trans = (byte) (readTranslateTable5and3[val] - 1);   // 0 - 31  (5 bits)
-    assert trans >= 0 && trans <= 31;
-    return (byte) (trans << 3);                               // left justify 5 bits
-  }
-
-  // ---------------------------------------------------------------------------------//
-  // getByte6and2
-  // ---------------------------------------------------------------------------------//
-
-  private byte getByte6and2 (byte b)
-  {
-    int val = (b & 0xFF) - 0x96;                              // 0 - 105
-    assert val >= 0 && val <= 105;
-    byte trans = (byte) (readTranslateTable6and2[val] - 1);   // 0 - 63  (6 bits)
-    assert trans >= 0 && trans <= 63;
-    return (byte) (trans << 2);                               // left justify 6 bits
-  }
-
   // ---------------------------------------------------------------------------------//
   // decode6and2
   // ---------------------------------------------------------------------------------//
 
   private byte[] decode6and2 (byte[] buffer, int offset)
   {
-    // convert legal disk values to actual 6 bit values
-    for (int i = 0; i < BUFFER_WITH_CHECKSUM_SIZE_DOS_33; i++)      // 343 bytes
-      decodeDos33a[i] = getByte6and2 (buffer[offset++]);
-
-    // reconstruct 342 bytes each with 6 bits
-    byte chk = 0;
-    for (int i = decodeDos33b.length - 1; i >= 0; i--)              // 342 bytes
-      chk = decodeDos33b[i] = (byte) (decodeDos33a[i + 1] ^ chk);
-    assert (chk ^ decodeDos33a[0]) == 0;
-
     // rearrange 342 bytes into 256
     byte[] decodedBuffer = new byte[BLOCK_SIZE];                    // 256 bytes
 
-    // move 6 bits into place
-    for (int i = 0; i < BLOCK_SIZE; i++)
-      decodedBuffer[i] = decodeDos33b[i + 86];
-
-    // reattach each byte's last 2 bits
-    for (int i = 0, j = 86, k = 172; i < 86; i++, j++, k++)
+    try
     {
-      byte val = decodeDos33b[i];
+      // convert legal disk values to actual 6 bit values
+      for (int i = 0; i < BUFFER_WITH_CHECKSUM_SIZE_DOS_33; i++)      // 343 bytes
+        decodeDos33a[i] = byteTranslator62.decode (buffer[offset++]);
 
-      decodedBuffer[i] |= reverse ((val & 0x0C) >> 2);
-      decodedBuffer[j] |= reverse ((val & 0x30) >> 4);
+      // reconstruct 342 bytes each with 6 bits
+      byte chk = 0;
+      for (int i = decodeDos33b.length - 1; i >= 0; i--)              // 342 bytes
+        chk = decodeDos33b[i] = (byte) (decodeDos33a[i + 1] ^ chk);
+      assert (chk ^ decodeDos33a[0]) == 0;
+
+      // move 6 bits into place
+      for (int i = 0; i < BLOCK_SIZE; i++)
+        decodedBuffer[i] = decodeDos33b[i + 86];
+
+      // reattach each byte's last 2 bits
+      for (int i = 0, j = 86, k = 172; i < 86; i++, j++, k++)
+      {
+        byte val = decodeDos33b[i];
+
+        decodedBuffer[i] |= reverse ((val & 0x0C) >> 2);
+        decodedBuffer[j] |= reverse ((val & 0x30) >> 4);
+
+        if (k < BLOCK_SIZE)
+          decodedBuffer[k] |= reverse ((val & 0xC0) >> 6);
+      }
+    }
+    catch (Exception e)
+    {
 
-      if (k < BLOCK_SIZE)
-        decodedBuffer[k] |= reverse ((val & 0xC0) >> 6);
     }
 
     return decodedBuffer;
@@ -376,7 +286,8 @@ class Nibblizer
 
     // remove two bits and convert to translated bytes
     for (int i = 0; i < BUFFER_WITH_CHECKSUM_SIZE_DOS_33; i++)
-      encodedBuffer[i] = writeTranslateTable6and2[(encodeDos33b[i] & 0xFC) / 4];
+      //      encodedBuffer[i] = writeTranslateTable6and2[(encodeDos33b[i] & 0xFC) / 4];
+      encodedBuffer[i] = byteTranslator62.encode (encodeDos33b[i]);
 
     return encodedBuffer;
   }
@@ -496,17 +407,11 @@ class Nibblizer
     {
       super (buffer, offset);
 
-      //      if (matchBytes (buffer, offset, addressPrologue33))
-      //      //          && matchBytes (buffer, offset + 11, epilogue))
-      //      {
       volume = decode4and4 (buffer, offset + 3);
       track = decode4and4 (buffer, offset + 5);
       sector = decode4and4 (buffer, offset + 7);
       checksum = decode4and4 (buffer, offset + 9);
       valid = true;
-      //      }
-      //      else
-      //        System.out.println (listBytes (buffer, offset, 14));
 
       length = 14;
     }
@@ -534,10 +439,10 @@ class Nibblizer
       if (matchBytes (buffer, offset, dataPrologue))
       {
         valid = true;
-        if (currentDosVersion == DosVersion.DOS_3_3)
-          dataBuffer = decode6and2 (buffer, offset + 3);
-        else if (currentDosVersion == DosVersion.DOS_3_2)
+        if (sectorsPerTrack == 13)
           dataBuffer = decode5and3 (buffer, offset + 3);
+        else
+          dataBuffer = decode6and2 (buffer, offset + 3);
       }
       else
       {

src/com/bytezone/diskbrowser/disk/V2dDisk.java

@@ -85,7 +85,7 @@ class V2dDisk
         int halfTrackNo = trackNumber % 4;
 
         if (halfTrackNo == 0)                               // only process full tracks
-          nibbler.processTrack (fullTrackNo, trackData, diskBuffer);
+          nibbler.processTrack (fullTrackNo, 16, trackData, diskBuffer);
         else
           System.out.printf ("%s skipping half track %02X / %02X%n", file.getName (),
               fullTrackNo, halfTrackNo);

src/com/bytezone/diskbrowser/disk/WozDisk.java

@@ -10,18 +10,20 @@ import com.bytezone.diskbrowser.utilities.Utility;
 
 class WozDisk
 {
+  private static final byte[] WOZ_DISK_HEADER =
+      { 0x57, 0x4F, 0x5A, 0x31, (byte) 0xFF, 0x0a, 0x0D, 0x0A };
   private static final int TRK_SIZE = 0x1A00;
   private static final int INFO_SIZE = 0x3C;
   private static final int TMAP_SIZE = 0xA0;
   private static final int DATA_SIZE = TRK_SIZE - 10;
-  private static byte[] header =
-      { 0x57, 0x4F, 0x5A, 0x31, (byte) 0xFF, 0x0a, 0x0D, 0x0A };
+
   private final boolean debug = false;
   private int diskType;                       // 5.25 or 3.5
-  int sectorsPerTrack;
 
   final File file;
-  final byte[] diskBuffer = new byte[4096 * 35];
+  byte[] diskBuffer;
+
+  private final MC3470 mc3470 = new MC3470 ();
 
   // ---------------------------------------------------------------------------------//
   // constructor
@@ -30,10 +32,9 @@ class WozDisk
   public WozDisk (File file) throws Exception
   {
     this.file = file;
-    Nibblizer nibbler = new Nibblizer ();
     byte[] buffer = readFile ();
 
-    if (!matches (header, buffer))
+    if (!matches (WOZ_DISK_HEADER, buffer))
       throw new Exception ("Header error");
 
     int cs1 = readInt (buffer, 8, 4);
@@ -88,7 +89,8 @@ class WozDisk
         if (debug)
           System.out.println ("Reading TRKS");
         int tracks = chunkSize / TRK_SIZE;
-        for (int track = 0; track < tracks; track++)
+
+        for (int trackNo = 0; trackNo < tracks; trackNo++)
         {
           int bytesUsed = readInt (buffer, ptr + DATA_SIZE, 2);
           int bitCount = readInt (buffer, ptr + DATA_SIZE + 2, 2);
@@ -99,22 +101,37 @@ class WozDisk
             System.out.printf ("Bit count  .... %,6d%n", bitCount);
           }
 
-          byte[] trackData = readTrack (buffer, ptr, bytesUsed, bitCount);
-          if (!nibbler.processTrack (track, trackData, diskBuffer))
+          try
           {
-            System.out.println ("Nibblizer failure");
-            if (debug)
-              System.out.println (HexFormatter.format (trackData));
-            break read;
+            mc3470.readTrack (buffer, ptr, bytesUsed, bitCount);
+
+            if (trackNo == 0)
+            {
+              if (mc3470.is13Sector ())
+                diskBuffer = new byte[35 * 13 * 256];
+              else if (mc3470.is16Sector ())
+                diskBuffer = new byte[35 * 16 * 256];
+              else
+              {
+                System.out.println ("unknown disk format");
+                break read;
+              }
+            }
+
+            mc3470.storeSectors (diskBuffer);
           }
+          catch (Exception e)
+          {
+            e.printStackTrace ();
+          }
+
           ptr += TRK_SIZE;
-          if (track == 0)
-            sectorsPerTrack = nibbler.sectorsPerTrack;
         }
       }
       else if ("META".equals (chunkId))
       {
         System.out.printf ("[%s]  %08X%n", chunkId, chunkSize);
+        System.out.println (HexFormatter.format (buffer, ptr, chunkSize));
         ptr += chunkSize;
       }
       else
@@ -125,6 +142,15 @@ class WozDisk
     }
   }
 
+  // ---------------------------------------------------------------------------------//
+  // getSectorsPerTrack
+  // ---------------------------------------------------------------------------------//
+
+  int getSectorsPerTrack ()
+  {
+    return mc3470.is13Sector () ? 13 : 16;
+  }
+
   // ---------------------------------------------------------------------------------//
   // readInt
   // ---------------------------------------------------------------------------------//
@@ -141,48 +167,6 @@ class WozDisk
     return value;
   }
 
-  // ---------------------------------------------------------------------------------//
-  // readTrack
-  // ---------------------------------------------------------------------------------//
-
-  private byte[] readTrack (byte[] buffer, int offset, int bytesUsed, int bitCount)
-  {
-    byte[] trackData = new byte[bytesUsed];
-    int value = 0;
-    int ptr = 0;
-    final int max = offset + bytesUsed;
-    int count = 0;
-
-    for (int i = offset; i < max; i++)
-    {
-      int b = buffer[i] & 0xFF;
-      for (int mask = 0x80; mask > 0; mask >>>= 1)
-      {
-        value <<= 1;
-        if ((b & mask) != 0)
-          value |= 1;
-
-        ++count;
-
-        if ((value & 0x80) != 0)            // is hi-bit set?
-        {
-          trackData[ptr++] = (byte) value;
-          value = 0;
-        }
-      }
-    }
-
-    if (value != 0)
-      System.out.printf ("********** Value not used: %01X%n", value);
-    if (debug && bitCount != count)
-    {
-      System.out.printf ("BitCount: %,4d%n", bitCount);
-      System.out.printf ("Actual  : %,4d%n", count);
-    }
-
-    return trackData;
-  }
-
   // ---------------------------------------------------------------------------------//
   // readFile
   // ---------------------------------------------------------------------------------//