diff --git a/BizHawk.Emulation.Cores/Consoles/Sega/gpgx/GPGX.cs b/BizHawk.Emulation.Cores/Consoles/Sega/gpgx/GPGX.cs
index b20a975033..f32b48acd4 100644
--- a/BizHawk.Emulation.Cores/Consoles/Sega/gpgx/GPGX.cs
+++ b/BizHawk.Emulation.Cores/Consoles/Sega/gpgx/GPGX.cs
@@ -23,6 +23,7 @@ namespace BizHawk.Emulation.Cores.Consoles.Sega.gpgx
 		bool disposed = false;
 
 		LibGPGX.load_archive_cb LoadCallback = null;
+		LibGPGX.input_cb InputCallback = null;
 
 		LibGPGX.InputData input = new LibGPGX.InputData();
 
@@ -111,6 +112,9 @@ namespace BizHawk.Emulation.Cores.Consoles.Sega.gpgx
 				update_video();
 
 				SetMemoryDomains();
+
+				InputCallback = new LibGPGX.input_cb(input_callback);
+				LibGPGX.gpgx_set_input_callback(InputCallback);
 			}
 			catch
 			{
@@ -285,6 +289,13 @@ namespace BizHawk.Emulation.Cores.Consoles.Sega.gpgx
 			ControllerDefinition = ControlConverter.ControllerDef;
 		}
 
+		// core callback for input
+		void input_callback()
+		{
+			CoreComm.InputCallback.Call();
+			IsLagFrame = false;
+		}
+
 		#endregion
 
 		// TODO: use render and rendersound
@@ -310,7 +321,6 @@ namespace BizHawk.Emulation.Cores.Consoles.Sega.gpgx
 			update_video();
 			update_audio();
 
-			IsLagFrame = false; // TODO
 			if (IsLagFrame)
 				LagCount++;
 		}
@@ -485,6 +495,8 @@ namespace BizHawk.Emulation.Cores.Consoles.Sega.gpgx
 
 		#endregion
 
+		#region debugging tools
+
 		public MemoryDomainList MemoryDomains { get; private set; }
 
 		unsafe void SetMemoryDomains()
@@ -524,6 +536,8 @@ namespace BizHawk.Emulation.Cores.Consoles.Sega.gpgx
 			return new List<KeyValuePair<string, int>>();
 		}
 
+		#endregion
+
 		public void Dispose()
 		{
 			if (!disposed)
diff --git a/BizHawk.Emulation.Cores/Consoles/Sega/gpgx/LibGPGX.cs b/BizHawk.Emulation.Cores/Consoles/Sega/gpgx/LibGPGX.cs
index b733498523..699c8392a2 100644
--- a/BizHawk.Emulation.Cores/Consoles/Sega/gpgx/LibGPGX.cs
+++ b/BizHawk.Emulation.Cores/Consoles/Sega/gpgx/LibGPGX.cs
@@ -122,6 +122,12 @@ namespace BizHawk.Emulation.Cores.Consoles.Sega.gpgx
 			DEVICE_ACTIVATOR = 0x0a,// Activator
 		};
 
+		[UnmanagedFunctionPointer(CallingConvention.Cdecl)]
+		public delegate void input_cb();
+
+		[DllImport("libgenplusgx.dll", CallingConvention = CallingConvention.Cdecl)]
+		public static extern void gpgx_set_input_callback(input_cb cb);
+
 		/// <summary>
 		/// not every flag is valid for every device!
 		/// </summary>
diff --git a/genplus-gx/cinterface/cinterface.c b/genplus-gx/cinterface/cinterface.c
index b75353be28..654376ce15 100644
--- a/genplus-gx/cinterface/cinterface.c
+++ b/genplus-gx/cinterface/cinterface.c
@@ -136,6 +136,19 @@ void osd_input_update(void)
 {
 }
 
+void (*input_callback_cb)(void);
+
+void real_input_callback(void)
+{
+	if (input_callback_cb)
+		input_callback_cb();
+}
+
+GPGX_EX void gpgx_set_input_callback(void (*fecb)(void))
+{
+	input_callback_cb = fecb;
+}
+
 int (*load_archive_cb)(const char *filename, unsigned char *buffer, int maxsize);
 
 // return 0 on failure, else actual loaded size
diff --git a/genplus-gx/core/io_ctrl.c b/genplus-gx/core/io_ctrl.c
index f221bf5835..a0baa1a3c9 100644
--- a/genplus-gx/core/io_ctrl.c
+++ b/genplus-gx/core/io_ctrl.c
@@ -377,8 +377,10 @@ unsigned int io_68k_read(unsigned int offset)
     case 0x02:  /* Port B Data */
     case 0x03:  /* Port C Data */
     {
-      unsigned int mask = 0x80 | io_reg[offset + 3];
-      unsigned int data = port[offset-1].data_r();
+	  unsigned int mask, data;
+	  real_input_callback();
+      mask = 0x80 | io_reg[offset + 3];
+      data = port[offset-1].data_r();
       return (io_reg[offset] & mask) | (data & ~mask);
     }
 
@@ -452,11 +454,13 @@ void io_z80_write(unsigned int offset, unsigned int data, unsigned int cycles)
 
 unsigned int io_z80_read(unsigned int offset)
 {
+  unsigned int data, ctrl;
+  real_input_callback();
   /* Read port A & port B input data */
-  unsigned int data = (port[0].data_r()) | (port[1].data_r() << 8);
+  data = (port[0].data_r()) | (port[1].data_r() << 8);
 
   /* I/O control register value */
-  unsigned int ctrl = io_reg[0x0F];
+  ctrl = io_reg[0x0F];
 
   /* I/O ports */
   if (offset)
diff --git a/genplus-gx/libretro/osd.h b/genplus-gx/libretro/osd.h
index e84d0f404f..4642b9b5e6 100644
--- a/genplus-gx/libretro/osd.h
+++ b/genplus-gx/libretro/osd.h
@@ -80,5 +80,6 @@ extern char MS_BIOS_JP[256];
 
 void osd_input_update(void);
 int load_archive(const char *filename, unsigned char *buffer, int maxsize, char *extension);
+void real_input_callback(void);
 
 #endif /* _OSD_H */
diff --git a/output/dll/libgenplusgx.dll b/output/dll/libgenplusgx.dll
index 83e230cd3e..57b88b2ac2 100644
Binary files a/output/dll/libgenplusgx.dll and b/output/dll/libgenplusgx.dll differ