diff --git a/src/common/EventHandlerSDL2.cxx b/src/common/EventHandlerSDL2.cxx
index bae54de10..d4fe4a075 100644
--- a/src/common/EventHandlerSDL2.cxx
+++ b/src/common/EventHandlerSDL2.cxx
@@ -41,7 +41,7 @@ void EventHandlerSDL2::enableTextEvents(bool enable)
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-const char* EventHandlerSDL2::nameForKey(StellaKey key)
+const char* EventHandlerSDL2::nameForKey(StellaKey key) const
 {
   return SDL_GetScancodeName(SDL_Scancode(key));
 }
diff --git a/src/common/EventHandlerSDL2.hxx b/src/common/EventHandlerSDL2.hxx
index 0416d0ccb..ae52bbe51 100644
--- a/src/common/EventHandlerSDL2.hxx
+++ b/src/common/EventHandlerSDL2.hxx
@@ -53,7 +53,7 @@ class EventHandlerSDL2 : public EventHandler
     /**
       Returns the human-readable name for a StellaKey.
     */
-    const char* nameForKey(StellaKey key);
+    const char* nameForKey(StellaKey key) const;
 
     /**
       Collects and dispatches any pending SDL2 events.
diff --git a/src/emucore/Cart.hxx b/src/emucore/Cart.hxx
index 1ef1fd164..f8b702b38 100644
--- a/src/emucore/Cart.hxx
+++ b/src/emucore/Cart.hxx
@@ -96,7 +96,7 @@ class Cartridge : public Device
     */
     void lockBank()   { myBankLocked = true;  }
     void unlockBank() { myBankLocked = false; }
-    bool bankLocked() { return myBankLocked;  }
+    bool bankLocked() const { return myBankLocked; }
 
     /**
       Get the default startup bank for a cart.  This is the bank where
diff --git a/src/emucore/Console.hxx b/src/emucore/Console.hxx
index ed88a831f..6663d8813 100644
--- a/src/emucore/Console.hxx
+++ b/src/emucore/Console.hxx
@@ -346,7 +346,7 @@ class Console : public Serializable
     Cartridge& myCart;
 
     // Reference to the event object to use
-    Event& myEvent;
+    const Event& myEvent;
 
     // Properties for the game
     Properties myProperties;
diff --git a/src/emucore/Control.cxx b/src/emucore/Control.cxx
index e09193f98..c03960acc 100644
--- a/src/emucore/Control.cxx
+++ b/src/emucore/Control.cxx
@@ -174,18 +174,6 @@ bool Controller::load(Serializer& in)
   return true;
 }
 
-// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-string Controller::name() const
-{
-  return myName;
-}
-
-// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-string Controller::about() const
-{
-  return name() + " in " + (myJack == Left ? "left port" : "right port");
-}
-
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 const Int32 Controller::maximumResistance = 0x7FFFFFFF;
 
diff --git a/src/emucore/Control.hxx b/src/emucore/Control.hxx
index c6d6c120b..fefcb6fce 100644
--- a/src/emucore/Control.hxx
+++ b/src/emucore/Control.hxx
@@ -101,8 +101,8 @@ class Controller : public Serializable
 
       @param jack   The jack the controller is plugged into
       @param event  The event object to use for events
-      @param type   The type for this controller
       @param system The system using this controller
+      @param type   The type for this controller
     */
     Controller(Jack jack, const Event& event, const System& system,
                Type type);
@@ -201,12 +201,13 @@ class Controller : public Serializable
     /**
       Returns the name of this controller.
     */
-    virtual string name() const;
+    virtual string name() const { return myName; }
 
     /**
       Returns more detailed information about this controller.
     */
-    virtual string about() const;
+    virtual string about() const
+    { return name() + " in " + (myJack == Left ? "left port" : "right port"); }
 
     /**
       The following two functions are used by the debugger to set
diff --git a/src/emucore/EventHandler.hxx b/src/emucore/EventHandler.hxx
index a09438dac..01eedd04e 100644
--- a/src/emucore/EventHandler.hxx
+++ b/src/emucore/EventHandler.hxx
@@ -109,7 +109,7 @@ class EventHandler
 
       @return The event object
     */
-    Event& event() { return myEvent; }
+    const Event& event() const { return myEvent; }
 
     /**
       Initialize state of this eventhandler.
@@ -347,7 +347,7 @@ class EventHandler
     /**
       Returns the human-readable name for a StellaKey.
     */
-    virtual const char* nameForKey(StellaKey key) { return EmptyString.c_str(); }
+    virtual const char* nameForKey(StellaKey key) const { return EmptyString.c_str(); }
 
     /**
       Collects and dispatches any pending events.
@@ -371,7 +371,7 @@ class EventHandler
     };
     void handleSystemEvent(SystemEvent e, int data1 = 0, int data2 = 0);
 
-    // An abstraction of joystick in Stella.
+    // An abstraction of a joystick in Stella.
     // A StellaJoystick holds its own event mapping information, space for
     // which is dynamically allocated based on the actual number of buttons,
     // axes, etc that the device contains.
@@ -415,7 +415,7 @@ class EventHandler
         int* axisLastValue;
 
       private:
-        void getValues(const string& list, IntArray& map);
+        void getValues(const string& list, IntArray& map) const;
 
         friend ostream& operator<<(ostream& os, const StellaJoystick& s) {
           os << "  ID: " << s.ID << ", name: " << s.name << ", numaxis: " << s.numAxes
@@ -465,7 +465,7 @@ class EventHandler
         Common::Array<StellaJoystick*> mySticks;
 
         void setStickDefaultMapping(int stick, Event::Type type, EventMode mode);
-        void printDatabase();
+        void printDatabase() const;
     };
 
     /**
diff --git a/src/emucore/EventJoyHandler.cxx b/src/emucore/EventJoyHandler.cxx
index 00e2b1183..fec2c892c 100644
--- a/src/emucore/EventJoyHandler.cxx
+++ b/src/emucore/EventJoyHandler.cxx
@@ -208,7 +208,7 @@ void EventHandler::StellaJoystick::eraseEvent(Event::Type event, EventMode mode)
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-void EventHandler::StellaJoystick::getValues(const string& list, IntArray& map)
+void EventHandler::StellaJoystick::getValues(const string& list, IntArray& map) const
 {
   map.clear();
   istringstream buf(list);
@@ -266,7 +266,7 @@ EventHandler::JoystickHandler::~JoystickHandler()
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-void EventHandler::JoystickHandler::printDatabase()
+void EventHandler::JoystickHandler::printDatabase() const
 {
   cerr << "---------------------------------------------------------" << endl
        << "joy database:"  << endl;
diff --git a/src/emucore/FrameBuffer.cxx b/src/emucore/FrameBuffer.cxx
index 7d686018b..c7fd9c118 100644
--- a/src/emucore/FrameBuffer.cxx
+++ b/src/emucore/FrameBuffer.cxx
@@ -721,7 +721,7 @@ void FrameBuffer::toggleGrabMouse()
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 uInt32 FrameBuffer::maxWindowSizeForScreen(uInt32 baseWidth, uInt32 baseHeight,
-                    uInt32 screenWidth, uInt32 screenHeight)
+                    uInt32 screenWidth, uInt32 screenHeight) const
 {
   uInt32 multiplier = 1;
   for(;;)
diff --git a/src/emucore/FrameBuffer.hxx b/src/emucore/FrameBuffer.hxx
index e7a5121f5..8b45d2713 100644
--- a/src/emucore/FrameBuffer.hxx
+++ b/src/emucore/FrameBuffer.hxx
@@ -454,13 +454,7 @@ class FrameBuffer
       still fit in the given screen dimensions.
     */
     uInt32 maxWindowSizeForScreen(uInt32 baseWidth, uInt32 baseHeight,
-                                  uInt32 screenWidth, uInt32 screenHeight);
-
-    /**
-      Determine all supported (windowed) TIA zoom levels for the current
-      framebuffer.  This will take into account any aspect ratio correction.
-    */
-    void setTIAZoomLevels(uInt32 basewidth, uInt32 baseheight);
+               uInt32 screenWidth, uInt32 screenHeight) const;
 
     /**
       Set all possible video modes (both windowed and fullscreen) available for
diff --git a/src/emucore/MT24LC256.cxx b/src/emucore/MT24LC256.cxx
index a1b0c618d..4695884d7 100644
--- a/src/emucore/MT24LC256.cxx
+++ b/src/emucore/MT24LC256.cxx
@@ -99,7 +99,7 @@ MT24LC256::~MT24LC256()
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-bool MT24LC256::readSDA()
+bool MT24LC256::readSDA() const
 {
   return jpee_mdat && jpee_sdat;
 }
diff --git a/src/emucore/MT24LC256.hxx b/src/emucore/MT24LC256.hxx
index cb82b98b4..ea40e35e4 100644
--- a/src/emucore/MT24LC256.hxx
+++ b/src/emucore/MT24LC256.hxx
@@ -51,7 +51,7 @@ class MT24LC256
 
   public:
     /** Read boolean data from the SDA line */
-    bool readSDA();
+    bool readSDA() const;
 
     /** Write boolean data to the SDA and SCL lines */
     void writeSDA(bool state);
diff --git a/src/emucore/OSystem.hxx b/src/emucore/OSystem.hxx
index 2d2093683..612ab1cce 100644
--- a/src/emucore/OSystem.hxx
+++ b/src/emucore/OSystem.hxx
@@ -341,7 +341,7 @@ class OSystem
       Answers whether the ROM launcher was actually successfully used
       at some point since the app started.
 
-      @return  True on success, otherwise false
+      @return  True if launcher was ever used, otherwise false
     */
     bool launcherUsed() const { return myLauncherUsed; }
 
diff --git a/src/emucore/Serializer.cxx b/src/emucore/Serializer.cxx
index 229231198..f9301623a 100644
--- a/src/emucore/Serializer.cxx
+++ b/src/emucore/Serializer.cxx
@@ -99,7 +99,7 @@ Serializer::~Serializer()
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-bool Serializer::isValid()
+bool Serializer::isValid() const
 {
   return myStream != NULL;
 }
@@ -113,7 +113,7 @@ void Serializer::reset()
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-uInt8 Serializer::getByte()
+uInt8 Serializer::getByte() const
 {
   char buf;
   myStream->read(&buf, 1);
@@ -122,13 +122,13 @@ uInt8 Serializer::getByte()
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-void Serializer::getByteArray(uInt8* array, uInt32 size)
+void Serializer::getByteArray(uInt8* array, uInt32 size) const
 {
   myStream->read((char*)array, size);
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-uInt16 Serializer::getShort()
+uInt16 Serializer::getShort() const
 {
   uInt16 val = 0;
   myStream->read((char*)&val, sizeof(uInt16));
@@ -137,13 +137,13 @@ uInt16 Serializer::getShort()
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-void Serializer::getShortArray(uInt16* array, uInt32 size)
+void Serializer::getShortArray(uInt16* array, uInt32 size) const
 {
   myStream->read((char*)array, sizeof(uInt16)*size);
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-uInt32 Serializer::getInt()
+uInt32 Serializer::getInt() const
 {
   uInt32 val = 0;
   myStream->read((char*)&val, sizeof(uInt32));
@@ -152,13 +152,13 @@ uInt32 Serializer::getInt()
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-void Serializer::getIntArray(uInt32* array, uInt32 size)
+void Serializer::getIntArray(uInt32* array, uInt32 size) const
 {
   myStream->read((char*)array, sizeof(uInt32)*size);
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-string Serializer::getString()
+string Serializer::getString() const
 {
   int len = getInt();
   string str;
@@ -169,7 +169,7 @@ string Serializer::getString()
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-bool Serializer::getBool()
+bool Serializer::getBool() const
 {
   return getByte() == TruePattern;
 }
diff --git a/src/emucore/Serializer.hxx b/src/emucore/Serializer.hxx
index 6a0243e01..969b2ab28 100644
--- a/src/emucore/Serializer.hxx
+++ b/src/emucore/Serializer.hxx
@@ -66,7 +66,7 @@ class Serializer
       Answers whether the serializer is currently initialized for reading
       and writing.
     */
-    bool isValid();
+    bool isValid() const;
 
     /**
       Resets the read/write location to the beginning of the stream.
@@ -78,7 +78,7 @@ class Serializer
 
       @result The byte value which has been read from the stream.
     */
-    uInt8 getByte();
+    uInt8 getByte() const;
 
     /**
       Reads a byte array (unsigned 8-bit) from the current input stream.
@@ -86,15 +86,14 @@ class Serializer
       @param array  The location to store the bytes read
       @param size   The size of the array (number of bytes to read)
     */
-    void getByteArray(uInt8* array, uInt32 size);
-
+    void getByteArray(uInt8* array, uInt32 size) const;
 
     /**
       Reads a short value (unsigned 16-bit) from the current input stream.
 
       @result The short value which has been read from the stream.
     */
-    uInt16 getShort();
+    uInt16 getShort() const;
 
     /**
       Reads a short array (unsigned 16-bit) from the current input stream.
@@ -102,14 +101,14 @@ class Serializer
       @param array  The location to store the shorts read
       @param size   The size of the array (number of shorts to read)
     */
-    void getShortArray(uInt16* array, uInt32 size);
+    void getShortArray(uInt16* array, uInt32 size) const;
 
     /**
       Reads an int value (unsigned 32-bit) from the current input stream.
 
       @result The int value which has been read from the stream.
     */
-    uInt32 getInt();
+    uInt32 getInt() const;
 
     /**
       Reads an integer array (unsigned 32-bit) from the current input stream.
@@ -117,21 +116,21 @@ class Serializer
       @param array  The location to store the integers read
       @param size   The size of the array (number of integers to read)
     */
-    void getIntArray(uInt32* array, uInt32 size);
+    void getIntArray(uInt32* array, uInt32 size) const;
 
     /**
       Reads a string from the current input stream.
 
       @result The string which has been read from the stream.
     */
-    string getString();
+    string getString() const;
 
     /**
       Reads a boolean value from the current input stream.
 
       @result The boolean value which has been read from the stream.
     */
-    bool getBool();
+    bool getBool() const;
 
     /**
       Writes an byte value (unsigned 8-bit) to the current output stream.
diff --git a/src/emucore/Settings.cxx b/src/emucore/Settings.cxx
index 9ef16ebcc..9bf591ac9 100644
--- a/src/emucore/Settings.cxx
+++ b/src/emucore/Settings.cxx
@@ -330,7 +330,7 @@ void Settings::validate()
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-void Settings::usage()
+void Settings::usage() const
 {
   cout << endl
     << "Stella version " << STELLA_VERSION << endl
diff --git a/src/emucore/Settings.hxx b/src/emucore/Settings.hxx
index c2b73b4d6..21b62f245 100644
--- a/src/emucore/Settings.hxx
+++ b/src/emucore/Settings.hxx
@@ -64,7 +64,7 @@ class Settings
     /**
       This method should be called to display usage information.
     */
-    void usage();
+    void usage() const;
 
     /**
       Get the value assigned to the specified key.
diff --git a/src/emucore/StateManager.cxx b/src/emucore/StateManager.cxx
index d53c461e1..02d07c970 100644
--- a/src/emucore/StateManager.cxx
+++ b/src/emucore/StateManager.cxx
@@ -42,12 +42,6 @@ StateManager::StateManager(OSystem* osystem)
   reset();
 }
 
-// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-bool StateManager::isActive()
-{
-  return myActiveMode != kOffMode;
-}
-
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 bool StateManager::toggleRecordMode()
 {
diff --git a/src/emucore/StateManager.hxx b/src/emucore/StateManager.hxx
index 668c7addc..7c1aae054 100644
--- a/src/emucore/StateManager.hxx
+++ b/src/emucore/StateManager.hxx
@@ -44,7 +44,7 @@ class StateManager
     /**
       Answers whether the manager is in record or playback mode
     */
-    bool isActive();
+    bool isActive() const { return myActiveMode != kOffMode; }
 
     bool toggleRecordMode();
     bool toggleRewindMode();
diff --git a/src/emucore/System.hxx b/src/emucore/System.hxx
index b04386055..ca44afcb2 100644
--- a/src/emucore/System.hxx
+++ b/src/emucore/System.hxx
@@ -146,7 +146,7 @@ class System : public Serializable
 
       @return The null device associated with the system
     */
-    NullDevice& nullDevice() { return myNullDevice; }
+    const NullDevice& nullDevice() const { return myNullDevice; }
 
     /**
       Get the total number of pages available in the system.
diff --git a/src/emucore/TIA.hxx b/src/emucore/TIA.hxx
index 7b1d67ed6..ec4b31266 100644
--- a/src/emucore/TIA.hxx
+++ b/src/emucore/TIA.hxx
@@ -220,7 +220,7 @@ class TIA : public Device
       Answers whether this TIA runs at NTSC or PAL scanrates,
       based on how many frames of out the total count are PAL frames.
     */
-    bool isPAL()
+    bool isPAL() const
       { return float(myPALFrameCounter) / myFrameCounter >= (25.0/60.0); }
 
     /**