diff --git a/src/GameGearIOPorts.cpp b/src/GameGearIOPorts.cpp
index ce2ddc96..19e6d853 100644
--- a/src/GameGearIOPorts.cpp
+++ b/src/GameGearIOPorts.cpp
@@ -18,11 +18,6 @@
  */
 
 #include "GameGearIOPorts.h"
-#include "Audio.h"
-#include "Video.h"
-#include "Input.h"
-#include "Cartridge.h"
-#include "Memory.h"
 
 GameGearIOPorts::GameGearIOPorts(Audio* pAudio, Video* pVideo, Input* pInput, Cartridge* pCartridge, Memory* pMemory)
 {
@@ -31,8 +26,7 @@ GameGearIOPorts::GameGearIOPorts(Audio* pAudio, Video* pVideo, Input* pInput, Ca
     m_pInput = pInput;
     m_pCartridge = pCartridge;
     m_pMemory = pMemory;
-    m_Port3F = 0;
-    m_Port3F_HC = 0;
+    Reset();
 }
 
 GameGearIOPorts::~GameGearIOPorts()
@@ -41,151 +35,13 @@ GameGearIOPorts::~GameGearIOPorts()
 
 void GameGearIOPorts::Reset()
 {
-    m_Port3F = 0;
-    m_Port3F_HC = 0;
-    m_Port2 = 0;
-}
-
-u8 GameGearIOPorts::DoInput(u8 port)
-{
-    if (port < 0x07)
-    {
-        switch (port)
-        {
-            case 0x00:
-            {
-                u8 port00 = m_pInput->GetPort00();
-                if (m_pCartridge->GetZone() != Cartridge::CartridgeJapanGG)
-                    port00 |= 0x40;
-                return port00;
-            }
-            case 0x01:
-                return 0x7F;
-            case 0x02:
-                return m_Port2;
-            case 0x03:
-            case 0x05:
-                return 0x00;
-            default:
-                return 0xFF;
-        }
-    }
-    else if (port < 0x40)
-    {
-        // Reads return $FF (GG)
-        Debug("--> ** Attempting to read from port $%X", port);
-        return 0xFF;
-    }
-    else if ((port >= 0x40) && (port < 0x80))
-    {
-        // Reads from even addresses return the V counter
-        // Reads from odd addresses return the H counter
-        if ((port & 0x01) == 0x00)
-            return m_pVideo->GetVCounter();
-        else
-            return m_pVideo->GetHCounter();
-    }
-    else if ((port >= 0x80) && (port < 0xC0))
-    {
-        // Reads from even addresses return the VDP data port contents
-        // Reads from odd address return the VDP status flags
-        if ((port & 0x01) == 0x00)
-            return m_pVideo->GetDataPort();
-        else
-            return m_pVideo->GetStatusFlags();
-    }
-    else
-    {
-        // Reads from $C0 and $DC return the I/O port A/B register.
-        // Reads from $C1 and $DD return the I/O port B/misc. register.
-        // The remaining locations return $FF.
-        switch (port)
-        {
-            case 0xC0:
-            case 0xDC:
-            {
-                return m_pInput->GetPortDC();
-            }
-            case 0xC1:
-            case 0xDD:
-            {
-                return ((m_pInput->GetPortDD() & 0x3F) | (m_Port3F & 0xC0));
-            }
-            default:
-            {
-                Debug("--> ** Attempting to read from port $%X", port);
-                return 0xFF;
-            }
-        }
-    }
-}
-
-void GameGearIOPorts::DoOutput(u8 port, u8 value)
-{
-    if (port < 0x07)
-    {
-        if (port == 0x06)
-        {
-            // SN76489 PSG
-            m_pAudio->WriteGGStereoRegister(value);
-        }
-        else if (port == 0x02)
-        {
-            m_Port2 = value;
-        }
-    }
-    else if (port < 0x40)
-    {
-        // Writes to even addresses go to memory control register.
-        // Writes to odd addresses go to I/O control register.
-        if ((port & 0x01) == 0x00)
-        {
-            Debug("--> ** Output to memory control port $%X: %X", port, value);
-            m_pMemory->SetPort3E(value);
-        }
-        else
-        {
-            if (((value  & 0x01) && !(m_Port3F_HC & 0x01)) || ((value  & 0x08) && !(m_Port3F_HC & 0x08)))
-                m_pVideo->LatchHCounter();
-            m_Port3F_HC = value & 0x05;
-
-            m_Port3F =  ((value & 0x80) | (value & 0x20) << 1) & 0xC0;
-            if (m_pCartridge->GetZone() == Cartridge::CartridgeJapanGG)
-                m_Port3F ^= 0xC0;
-        }
-    }
-    else if ((port >= 0x40) && (port < 0x80))
-    {
-        // Writes to any address go to the SN76489 PSG
-        m_pAudio->WriteAudioRegister(value);
-    }
-    else if ((port >= 0x80) && (port < 0xC0))
-    {
-        // Writes to even addresses go to the VDP data port.
-        // Writes to odd addresses go to the VDP control port.
-        if ((port & 0x01) == 0x00)
-            m_pVideo->WriteData(value);
-        else
-            m_pVideo->WriteControl(value);
-    }
-#ifdef DEBUG_GEARSYSTEM
-    else
-    {
-        // Writes have no effect.
-        if ((port == 0xDE) || (port == 0xDF))
-        {
-            Debug("--> ** Output to keyboard port $%X: %X", port, value);
-        }
-        else if ((port == 0xF0) || (port == 0xF1) || (port == 0xF2))
-        {
-            Debug("--> ** Output to YM2413 port $%X: %X", port, value);
-        }
-        else
-        {
-            Debug("--> ** Output to port $%X: %X", port, value);
-        }
-    }
-#endif
+    m_Port3F = 0xFF;
+    m_Ports[0] = 0xC0;
+    m_Ports[1] = 0x7F;
+    m_Ports[2] = 0xFF;
+    m_Ports[3] = 0x00;
+    m_Ports[4] = 0xFF;
+    m_Ports[5] = 0x00;
 }
 
 void GameGearIOPorts::SaveState(std::ostream& stream)
@@ -193,7 +49,7 @@ void GameGearIOPorts::SaveState(std::ostream& stream)
     using namespace std;
 
     stream.write(reinterpret_cast<const char*> (&m_Port3F), sizeof(m_Port3F));
-    stream.write(reinterpret_cast<const char*> (&m_Port3F_HC), sizeof(m_Port3F_HC));
+    stream.write(reinterpret_cast<const char*> (m_Ports), sizeof(m_Ports));
 }
 
 void GameGearIOPorts::LoadState(std::istream& stream)
@@ -201,5 +57,5 @@ void GameGearIOPorts::LoadState(std::istream& stream)
     using namespace std;
 
     stream.read(reinterpret_cast<char*> (&m_Port3F), sizeof(m_Port3F));
-    stream.read(reinterpret_cast<char*> (&m_Port3F_HC), sizeof(m_Port3F_HC));
+    stream.read(reinterpret_cast<char*> (m_Ports), sizeof(m_Ports));
 }
diff --git a/src/GameGearIOPorts.h b/src/GameGearIOPorts.h
index 1afb23b0..d1359a7c 100644
--- a/src/GameGearIOPorts.h
+++ b/src/GameGearIOPorts.h
@@ -38,6 +38,7 @@ class GameGearIOPorts : public IOPorts
     virtual void DoOutput(u8 port, u8 value);
     virtual void SaveState(std::ostream& stream);
     virtual void LoadState(std::istream& stream);
+
 private:
     Audio* m_pAudio;
     Video* m_pVideo;
@@ -45,8 +46,147 @@ class GameGearIOPorts : public IOPorts
     Memory* m_pMemory;
     Cartridge* m_pCartridge;
     u8 m_Port3F;
-    u8 m_Port3F_HC;
-    u8 m_Port2;
+    u8 m_Ports[6];
 };
 
+#include "Audio.h"
+#include "Video.h"
+#include "Input.h"
+#include "Cartridge.h"
+#include "Memory.h"
+
+inline u8 GameGearIOPorts::DoInput(u8 port)
+{
+    if (port < 0x07)
+    {
+        if (port == 0x00)
+        {
+            u8 start_button = m_pInput->GetPort00();
+            if (m_pCartridge->GetZone() != Cartridge::CartridgeJapanGG)
+                start_button |= 0x40;
+            return start_button;
+        }
+        else if (port < 6)
+            return m_Ports[port];
+        else
+            return 0xFF;
+    }
+    else if (port < 0x40)
+    {
+        // Reads return $FF (GG)
+        Debug("--> ** Attempting to read from port $%X", port);
+        return 0xFF;
+    }
+    else if (port < 0x80)
+    {
+        // Reads from even addresses return the V counter
+        if ((port & 0x01) == 0x00)
+            return m_pVideo->GetVCounter();
+        // Reads from odd addresses return the H counter
+        else
+            return m_pVideo->GetHCounter();
+    }
+    else if (port < 0xC0)
+    {
+        // Reads from even addresses return the VDP data port contents
+        if ((port & 0x01) == 0x00)
+            return m_pVideo->GetDataPort();
+        // Reads from odd address return the VDP status flags
+        else
+            return m_pVideo->GetStatusFlags();
+    }
+    else
+    {
+        switch (port)
+        {
+            // Reads from $C0 and $DC return the I/O port A/B register.
+            case 0xC0:
+            case 0xDC:
+            {
+                return m_pInput->GetPortDC();
+            }
+            // Reads from $C1 and $DD return the I/O port B/misc. register.
+            case 0xC1:
+            case 0xDD:
+            {
+                return ((m_pInput->GetPortDD() & 0x3F) | (m_Port3F & 0xC0));
+            }
+            // The remaining locations return $FF.
+            default:
+            {
+                Debug("--> ** Attempting to read from port $%X", port);
+                return 0xFF;
+            }
+        }
+    }
+}
+
+inline void GameGearIOPorts::DoOutput(u8 port, u8 value)
+{
+    if (port < 0x07)
+    {
+        if (port == 0x06)
+        {
+            // SN76489 PSG
+            m_pAudio->WriteGGStereoRegister(value);
+        }
+        else if (port != 0x00)
+        {
+            m_Ports[port] = value;
+        }
+    }
+    else if (port < 0x40)
+    {
+        // Writes to even addresses go to memory control register.
+        if ((port & 0x01) == 0x00)
+        {
+            Debug("--> ** Output to memory control port $%X: %X", port, value);
+            m_pMemory->SetPort3E(value);
+        }
+        // Writes to odd addresses go to I/O control register.
+        else
+        {
+            bool th_changed_a = (value & 0x02) && (value & 0x20) && !(m_Port3F & 0x20);
+            bool th_changed_b = (value & 0x08) && (value & 0x80) && !(m_Port3F & 0x80);
+
+            if (th_changed_a || th_changed_b)
+                m_pVideo->LatchHCounter();
+
+            m_Port3F = value;
+        }
+    }
+    else if (port < 0x80)
+    {
+        // Writes to any address go to the SN76489 PSG
+        m_pAudio->WriteAudioRegister(value);
+    }
+    else if (port < 0xC0)
+    {
+        // Writes to even addresses go to the VDP data port.
+        if ((port & 0x01) == 0x00)
+            m_pVideo->WriteData(value);
+        // Writes to odd addresses go to the VDP control port.
+        else
+            m_pVideo->WriteControl(value);
+    }
+#ifdef DEBUG_GEARSYSTEM
+    else
+    {
+        // Writes have no effect.
+        if ((port == 0xDE) || (port == 0xDF))
+        {
+            Debug("--> ** Output to keyboard port $%X: %X", port, value);
+        }
+        else if ((port == 0xF0) || (port == 0xF1) || (port == 0xF2))
+        {
+            Debug("--> ** Output to YM2413 port $%X: %X", port, value);
+        }
+        else
+        {
+            Debug("--> ** Output to port $%X: %X", port, value);
+        }
+    }
+#endif
+}
+
 #endif	/* GAMEGEARIOPORTS_H */
diff --git a/src/Input.cpp b/src/Input.cpp
index 7347945c..17cce3f8 100644
--- a/src/Input.cpp
+++ b/src/Input.cpp
@@ -123,14 +123,7 @@ u8 Input::GetPortDD()
 
 u8 Input::GetPort00()
 {
-    if (m_bPhaser)
-    {
-        return 0x00;
-    }
-    else
-    {
-        return (IsSetBit(m_Joypad1, Key_Start) ? 0x80 : 0) & 0x80;
-    }
+    return (IsSetBit(m_Joypad1, Key_Start) ? 0x80 : 0) & 0x80;
 }
 
 u8 Input::GetGlassesRegistry()
diff --git a/src/SmsIOPorts.cpp b/src/SmsIOPorts.cpp
index 9238c6d3..d19d874f 100644
--- a/src/SmsIOPorts.cpp
+++ b/src/SmsIOPorts.cpp
@@ -27,7 +27,7 @@ SmsIOPorts::SmsIOPorts(Audio* pAudio, Video* pVideo, Input* pInput, Cartridge* p
     m_pCartridge = pCartridge;
     m_pMemory = pMemory;
     m_pProcessor = pProcessor;
-    m_Port3F = 0xFF;
+    Reset();
 }
 
 SmsIOPorts::~SmsIOPorts()
diff --git a/src/SmsIOPorts.h b/src/SmsIOPorts.h
index 47ff189a..7eb35ddd 100644
--- a/src/SmsIOPorts.h
+++ b/src/SmsIOPorts.h
@@ -39,6 +39,7 @@ class SmsIOPorts : public IOPorts
     void DoOutput(u8 port, u8 value);
     void SaveState(std::ostream& stream);
     void LoadState(std::istream& stream);
+
 private:
     Audio* m_pAudio;
     Video* m_pVideo;
@@ -46,7 +47,6 @@ class SmsIOPorts : public IOPorts
     Cartridge* m_pCartridge;
     Memory* m_pMemory;
     Processor* m_pProcessor;
-
     u8 m_Port3F;
 };
 
@@ -65,7 +65,7 @@ inline u8 SmsIOPorts::DoInput(u8 port)
         Debug("--> ** Attempting to read from port $%02X", port);
         return 0xFF;
     }
-    else if ((port >= 0x40) && (port < 0x80))
+    else if (port < 0x80)
     {
         // Reads from even addresses return the V counter
         if ((port & 0x01) == 0x00)
@@ -74,7 +74,7 @@ inline u8 SmsIOPorts::DoInput(u8 port)
         else
             return m_pVideo->GetHCounter();
     }
-    else if ((port >= 0x80) && (port < 0xC0))
+    else if (port < 0xC0)
     {
         // Reads from even addresses return the VDP data port contents
         if ((port & 0x01) == 0x00)
@@ -155,14 +155,14 @@ inline void SmsIOPorts::DoOutput(u8 port, u8 value)
             m_Port3F = value;
         }
     }
-    else if ((port >= 0x40) && (port < 0x80))
+    else if (port < 0x80)
     {
         // Writes to any address go to the SN76489 PSG
         m_pAudio->WriteAudioRegister(value);
         if (m_pCartridge->IsSG1000())
             m_pProcessor->InjectTStates(32);
     }
-    else if ((port >= 0x80) && (port < 0xC0))
+    else if (port < 0xC0)
     {
         // Writes to even addresses go to the VDP data port.
         if ((port & 0x01) == 0x00)