diff --git a/stella/src/debugger/ConstExpression.cxx b/stella/src/debugger/ConstExpression.cxx
new file mode 100644
index 000000000..c99d5e858
--- /dev/null
+++ b/stella/src/debugger/ConstExpression.cxx
@@ -0,0 +1,27 @@
+//============================================================================
+//
+//   SSSS    tt          lll  lll       
+//  SS  SS   tt           ll   ll        
+//  SS     tttttt  eeee   ll   ll   aaaa 
+//   SSSS    tt   ee  ee  ll   ll      aa
+//      SS   tt   eeeeee  ll   ll   aaaaa  --  "An Atari 2600 VCS Emulator"
+//  SS  SS   tt   ee      ll   ll  aa  aa
+//   SSSS     ttt  eeeee llll llll  aaaaa
+//
+// Copyright (c) 1995-2005 by Bradford W. Mott and the Stella team
+//
+// See the file "license" for information on usage and redistribution of
+// this file, and for a DISCLAIMER OF ALL WARRANTIES.
+//
+// $Id: ConstExpression.cxx,v 1.1 2005-07-12 17:02:35 stephena Exp $
+//============================================================================
+
+#include "Expression.hxx"
+#include "ConstExpression.hxx"
+
+// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+ConstExpression::ConstExpression(const int value)
+  : Expression(0, 0),
+    myValue(value)
+{
+}
diff --git a/stella/src/debugger/ConstExpression.hxx b/stella/src/debugger/ConstExpression.hxx
new file mode 100644
index 000000000..d0fc8ce99
--- /dev/null
+++ b/stella/src/debugger/ConstExpression.hxx
@@ -0,0 +1,41 @@
+//============================================================================
+//
+//   SSSS    tt          lll  lll       
+//  SS  SS   tt           ll   ll        
+//  SS     tttttt  eeee   ll   ll   aaaa 
+//   SSSS    tt   ee  ee  ll   ll      aa
+//      SS   tt   eeeeee  ll   ll   aaaaa  --  "An Atari 2600 VCS Emulator"
+//  SS  SS   tt   ee      ll   ll  aa  aa
+//   SSSS     ttt  eeeee llll llll  aaaaa
+//
+// Copyright (c) 1995-2005 by Bradford W. Mott and the Stella team
+//
+// See the file "license" for information on usage and redistribution of
+// this file, and for a DISCLAIMER OF ALL WARRANTIES.
+//
+// $Id: ConstExpression.hxx,v 1.1 2005-07-12 17:02:35 stephena Exp $
+//============================================================================
+
+#ifndef CONST_EXPRESSION_HXX
+#define CONST_EXPRESSION_HXX
+
+#include "Expression.hxx"
+
+/**
+  This class provides an implementation of an constant expression;
+  that is, one that consists solely of a constant integer value.
+
+  @author  Stephen Anthony
+  @version $Id: ConstExpression.hxx,v 1.1 2005-07-12 17:02:35 stephena Exp $
+*/
+class ConstExpression : public Expression
+{
+  public:
+    ConstExpression(const int value);
+    int evaluate() { return myValue; }
+
+  private:
+    int myValue;
+};
+
+#endif
diff --git a/stella/src/debugger/Expression.cxx b/stella/src/debugger/Expression.cxx
new file mode 100644
index 000000000..0dd136f3f
--- /dev/null
+++ b/stella/src/debugger/Expression.cxx
@@ -0,0 +1,33 @@
+//============================================================================
+//
+//   SSSS    tt          lll  lll       
+//  SS  SS   tt           ll   ll        
+//  SS     tttttt  eeee   ll   ll   aaaa 
+//   SSSS    tt   ee  ee  ll   ll      aa
+//      SS   tt   eeeeee  ll   ll   aaaaa  --  "An Atari 2600 VCS Emulator"
+//  SS  SS   tt   ee      ll   ll  aa  aa
+//   SSSS     ttt  eeeee llll llll  aaaaa
+//
+// Copyright (c) 1995-2005 by Bradford W. Mott and the Stella team
+//
+// See the file "license" for information on usage and redistribution of
+// this file, and for a DISCLAIMER OF ALL WARRANTIES.
+//
+// $Id: Expression.cxx,v 1.1 2005-07-12 17:02:35 stephena Exp $
+//============================================================================
+
+#include "Expression.hxx"
+
+// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+Expression::Expression(Expression* lhs, Expression* rhs)
+  : myLHS(lhs),
+    myRHS(rhs)
+{
+}
+
+// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+Expression::~Expression()
+{
+  delete myLHS;
+  delete myRHS;
+}
diff --git a/stella/src/debugger/Expression.hxx b/stella/src/debugger/Expression.hxx
new file mode 100644
index 000000000..1c0cd5a1a
--- /dev/null
+++ b/stella/src/debugger/Expression.hxx
@@ -0,0 +1,44 @@
+//============================================================================
+//
+//   SSSS    tt          lll  lll       
+//  SS  SS   tt           ll   ll        
+//  SS     tttttt  eeee   ll   ll   aaaa 
+//   SSSS    tt   ee  ee  ll   ll      aa
+//      SS   tt   eeeeee  ll   ll   aaaaa  --  "An Atari 2600 VCS Emulator"
+//  SS  SS   tt   ee      ll   ll  aa  aa
+//   SSSS     ttt  eeeee llll llll  aaaaa
+//
+// Copyright (c) 1995-2005 by Bradford W. Mott and the Stella team
+//
+// See the file "license" for information on usage and redistribution of
+// this file, and for a DISCLAIMER OF ALL WARRANTIES.
+//
+// $Id: Expression.hxx,v 1.1 2005-07-12 17:02:35 stephena Exp $
+//============================================================================
+
+#ifndef EXPRESSION_HXX
+#define EXPRESSION_HXX
+
+/**
+  This class provides an implementation of an expression node, which
+  is a construct that is given two other expressions and evaluates and
+  returns the result.  When placed in a tree, a collection of such nodes
+  can represent complex expression statements.
+
+  @author  Stephen Anthony
+  @version $Id: Expression.hxx,v 1.1 2005-07-12 17:02:35 stephena Exp $
+*/
+class Expression
+{
+  public:
+    Expression(Expression* lhs, Expression* rhs);
+    virtual ~Expression();
+
+    virtual int evaluate() = 0;
+
+  protected:
+    Expression* myLHS;
+    Expression* myRHS;
+};
+
+#endif
diff --git a/stella/src/debugger/module.mk b/stella/src/debugger/module.mk
index 6b2ed169f..dde32993a 100644
--- a/stella/src/debugger/module.mk
+++ b/stella/src/debugger/module.mk
@@ -4,6 +4,8 @@ MODULE_OBJS := \
 	src/debugger/Debugger.o \
 	src/debugger/DebuggerParser.o \
 	src/debugger/EquateList.o \
+	src/debugger/Expression.o \
+	src/debugger/ConstExpression.o \
 	src/debugger/PackedBitArray.o \
 	src/debugger/CpuDebug.o \
 	src/debugger/RamDebug.o \