diff --git a/src/com/webcodepro/applecommander/storage/os/dos33/DosFileEntry.java b/src/com/webcodepro/applecommander/storage/os/dos33/DosFileEntry.java
index 18fa173..6836165 100644
--- a/src/com/webcodepro/applecommander/storage/os/dos33/DosFileEntry.java
+++ b/src/com/webcodepro/applecommander/storage/os/dos33/DosFileEntry.java
@@ -29,6 +29,7 @@ import com.webcodepro.applecommander.storage.FileEntry;
 import com.webcodepro.applecommander.storage.FileFilter;
 import com.webcodepro.applecommander.storage.FormattedDisk;
 import com.webcodepro.applecommander.storage.filters.ApplesoftFileFilter;
+import com.webcodepro.applecommander.storage.filters.AssemblySourceFileFilter;
 import com.webcodepro.applecommander.storage.filters.BinaryFileFilter;
 import com.webcodepro.applecommander.storage.filters.GraphicsFileFilter;
 import com.webcodepro.applecommander.storage.filters.IntegerBasicFileFilter;
@@ -388,6 +389,8 @@ public class DosFileEntry implements FileEntry {
 			return new ApplesoftFileFilter();
 		} else if (isIntegerBasicFile()) {
 			return new IntegerBasicFileFilter();
+		} else if (isAssemblySourceFile()) {
+			return new AssemblySourceFileFilter();
 		} else if (isTextFile()) {
 			return new TextFileFilter();
 		} else if (isBinaryFile()) {
@@ -406,6 +409,16 @@ public class DosFileEntry implements FileEntry {
 		}
 		return new BinaryFileFilter();
 	}
+	
+	/**
+	 * Determine if this is an assembly source code file.
+	 */
+	public boolean isAssemblySourceFile() {
+		boolean rightFiletype = isTextFile() || isBinaryFile();
+		if (rightFiletype && getFilename().endsWith(".S")) return true;
+		if (rightFiletype && getFilename().startsWith("T.")) return true;
+		return false;
+	}
 
 	/**
 	 * Determine if this is a text file.
diff --git a/src/com/webcodepro/applecommander/storage/os/prodos/ProdosFileEntry.java b/src/com/webcodepro/applecommander/storage/os/prodos/ProdosFileEntry.java
index 68cfd0b..bf65f7d 100644
--- a/src/com/webcodepro/applecommander/storage/os/prodos/ProdosFileEntry.java
+++ b/src/com/webcodepro/applecommander/storage/os/prodos/ProdosFileEntry.java
@@ -33,6 +33,7 @@ import com.webcodepro.applecommander.storage.filters.AppleWorksDataBaseFileFilte
 import com.webcodepro.applecommander.storage.filters.AppleWorksSpreadSheetFileFilter;
 import com.webcodepro.applecommander.storage.filters.AppleWorksWordProcessorFileFilter;
 import com.webcodepro.applecommander.storage.filters.ApplesoftFileFilter;
+import com.webcodepro.applecommander.storage.filters.AssemblySourceFileFilter;
 import com.webcodepro.applecommander.storage.filters.BinaryFileFilter;
 import com.webcodepro.applecommander.storage.filters.GraphicsFileFilter;
 import com.webcodepro.applecommander.storage.filters.IntegerBasicFileFilter;
@@ -456,6 +457,10 @@ public class ProdosFileEntry extends ProdosCommonEntry implements FileEntry {
 		
 		switch (filetype) {
 		case 0x04:		// TXT
+			if (getFilename().endsWith(".S")) {
+				return new AssemblySourceFileFilter();			
+			}
+			return new TextFileFilter();
 		case 0xb0:		// SRC
 			return new TextFileFilter();
 		case 0x19:		// ADB