diff --git a/lib/ac-api/src/main/java/com/webcodepro/applecommander/storage/Disk.java b/lib/ac-api/src/main/java/com/webcodepro/applecommander/storage/Disk.java
index b783c71..56eb21d 100644
--- a/lib/ac-api/src/main/java/com/webcodepro/applecommander/storage/Disk.java
+++ b/lib/ac-api/src/main/java/com/webcodepro/applecommander/storage/Disk.java
@@ -278,7 +278,7 @@ public class Disk {
 					rc = 0;
 				} else {
 					imageOrder = proDosOrder;
-					if (knownProDOSOrder || isProdosFormat() || isDosFormat()) {
+					if (knownProDOSOrder || isProdosFormat() || isDosFormat() || isRdos33Format()) {
 						rc = 0;
 					}
 				}
@@ -791,9 +791,20 @@ public class Disk {
 		if (!is140KbDisk()) return false;
 		byte[] block = readSector(0, 0x0d);
 		String id = AppleUtil.getString(block, 0xe0, 4);
-		return "RDOS".equals(id); //$NON-NLS-1$
+		return "RDOS".equals(id) || isRdos33Format(); //$NON-NLS-1$
 	}
 	
+	/**
+	 * Test the disk format to see if this is a RDOS 33 formatted
+	 * disk.
+	 */
+	public boolean isRdos33Format() {
+		if (!is140KbDisk()) return false;
+		byte[] block = readSector(1, 0x0);
+		String id = AppleUtil.getString(block, 0x0, 6);
+		return "RDOS 3".equals(id); //$NON-NLS-1$
+	}
+
 	/**
 	 * Test the disk format to see if this is a WP formatted
 	 * disk.
diff --git a/lib/ac-api/src/main/java/com/webcodepro/applecommander/storage/os/rdos/RdosFormatDisk.java b/lib/ac-api/src/main/java/com/webcodepro/applecommander/storage/os/rdos/RdosFormatDisk.java
index 7c7ef37..e961eb4 100644
--- a/lib/ac-api/src/main/java/com/webcodepro/applecommander/storage/os/rdos/RdosFormatDisk.java
+++ b/lib/ac-api/src/main/java/com/webcodepro/applecommander/storage/os/rdos/RdosFormatDisk.java
@@ -30,6 +30,7 @@ import com.webcodepro.applecommander.storage.FileEntry;
 import com.webcodepro.applecommander.storage.FormattedDisk;
 import com.webcodepro.applecommander.storage.StorageBundle;
 import com.webcodepro.applecommander.storage.physical.ImageOrder;
+import com.webcodepro.applecommander.storage.physical.ProdosOrder;
 import com.webcodepro.applecommander.util.AppleUtil;
 import com.webcodepro.applecommander.util.TextBundle;
 
@@ -170,6 +171,24 @@ public class RdosFormatDisk extends FormattedDisk {
 		writeSector(track, sector, data);
 	}
 
+	/**
+	 * Read the block from the disk image.
+	 */
+	public byte[] readBlock(int block) {
+		int track = block / 16;
+		int sector = block % 16;
+		return getImageOrder().readSector(track, sector);
+	}
+	
+	/**
+	 * Write the block to the disk image.
+	 */
+	public void writeBlock(int block, byte[] data) {
+		int track = block / 16;
+		int sector = block % 16;
+		getImageOrder().writeSector(track, sector, data);
+	}
+
 	/**
 	 * RDOS really does not have a disk name.  Fake one.
 	 */
@@ -392,7 +411,12 @@ public class RdosFormatDisk extends FormattedDisk {
 		byte[] fileData = new byte[rdosEntry.getSizeInBlocks() * SECTOR_SIZE];
 		int offset = 0;
 		for (int blockOffset = 0; blockOffset < rdosEntry.getSizeInBlocks(); blockOffset++) {
-			byte[] blockData = readRdosBlock(startingBlock + blockOffset);
+			byte[] blockData;
+			if (getImageOrder() instanceof ProdosOrder) {
+				blockData = readBlock(startingBlock + blockOffset);
+			} else {
+				blockData = readRdosBlock(startingBlock + blockOffset);
+			}
 			System.arraycopy(blockData, 0, fileData, offset, blockData.length);
 			offset+= blockData.length;
 		}