diff --git a/BizHawk.Client.EmuHawk/MainForm.cs b/BizHawk.Client.EmuHawk/MainForm.cs
index ff2a30e2f6..09ee284302 100644
--- a/BizHawk.Client.EmuHawk/MainForm.cs
+++ b/BizHawk.Client.EmuHawk/MainForm.cs
@@ -3057,10 +3057,15 @@ namespace BizHawk.Client.EmuHawk
 								case DiscType.SonyPSX:
 									game.System = "PSX";
 									break;
+								case DiscType.MegaCD:
+									game.System = "GEN";
+									break;
 								case DiscType.TurboCD:
 								case DiscType.UnknownCDFS:
 								case DiscType.UnknownFormat:
-								default: // PCECD was bizhawk's first CD core, so this prevents regressions
+								default:// PCECD was bizhawk's first CD core,
+										// and during that time, all CDs were blindly sent to it
+										// so this prevents regressions
 									game.System = "PCECD";
 									break;
 							}
@@ -3068,6 +3073,13 @@ namespace BizHawk.Client.EmuHawk
 
 						switch (game.System)
 						{
+							case "GEN":
+								{
+									var genesis = new BizHawk.Emulation.Cores.Consoles.Sega.gpgx.GPGX(
+										nextComm, null, disc, "GEN", true, Emulation.Cores.Consoles.Sega.gpgx.GPGX.ControlType.Normal);
+									nextEmulator = genesis;
+								}
+								break;
 							case "SAT":
 								{
 									var saturn = new Yabause(nextComm, disc, Global.Config.SaturnUseGL);
@@ -3385,7 +3397,7 @@ namespace BizHawk.Client.EmuHawk
 				Text = DisplayNameForSystem(game.System) + " - " + game.Name;
 				ResetRewindBuffer();
 
-				if (Global.Emulator.CoreComm.RomStatusDetails == null)
+				if (Global.Emulator.CoreComm.RomStatusDetails == null && rom != null)
 				{
 					Global.Emulator.CoreComm.RomStatusDetails =
 						string.Format("{0}\r\nSHA1:{1}\r\nMD5:{2}\r\n",
diff --git a/BizHawk.Client.EmuHawk/config/FirmwaresConfig.cs b/BizHawk.Client.EmuHawk/config/FirmwaresConfig.cs
index f31a7f2253..bb1a49fa15 100644
--- a/BizHawk.Client.EmuHawk/config/FirmwaresConfig.cs
+++ b/BizHawk.Client.EmuHawk/config/FirmwaresConfig.cs
@@ -41,6 +41,7 @@ namespace BizHawk.Client.EmuHawk
 				{ "TI83", "TI-83" },
 				{ "INTV", "Intellivision" },
 				{ "C64", "C64" },
+				{ "GEN", "Genesis" },
 			};
 
 		public string TargetSystem = null;
@@ -126,7 +127,10 @@ namespace BizHawk.Client.EmuHawk
 				//build the groups in the listview as we go:
 				if (!groups.ContainsKey(fr.systemId))
 				{
-					lvFirmwares.Groups.Add(fr.systemId, SystemGroupNames[fr.systemId]);
+					string name;
+					if (!SystemGroupNames.TryGetValue(fr.systemId, out name))
+						name = "FIX ME (FirmwaresConfig.cs)";
+					lvFirmwares.Groups.Add(fr.systemId, name);
 					var lvg = lvFirmwares.Groups[lvFirmwares.Groups.Count - 1];
 					groups[fr.systemId] = lvg;
 				}
diff --git a/BizHawk.Emulation.Common/Database/FirmwareDatabase.cs b/BizHawk.Emulation.Common/Database/FirmwareDatabase.cs
index 23f617d156..678eb5434e 100644
--- a/BizHawk.Emulation.Common/Database/FirmwareDatabase.cs
+++ b/BizHawk.Emulation.Common/Database/FirmwareDatabase.cs
@@ -89,6 +89,9 @@ namespace BizHawk.Emulation.Common
 			var us_scd1_9210 = File("f4f315adcef9b8feb0364c21ab7f0eaf5457f3ed", "us_scd1_9210.bin", "Sega CD US (9210)");
 			var us_scd2_9303 = File("bd3ee0c8ab732468748bf98953603ce772612704", "us_scd2_9303.bin", "Sega CD US (9303)");
 
+			Firmware("GEN", "CD_BIOS_EU", "Mega CD Bios (Europe)");
+			Firmware("GEN", "CD_BIOS_JP", "Mega CD Bios (Japan)");
+			Firmware("GEN", "CD_BIOS_US", "Sega CD Bios (USA)");
 			Option("GEN", "CD_BIOS_EU", eu_mcd1_9210);
 			Option("GEN", "CD_BIOS_EU", eu_mcd2_9303);
 			Option("GEN", "CD_BIOS_EU", eu_mcd2_9306);
@@ -133,14 +136,16 @@ namespace BizHawk.Emulation.Common
 		//defines a firmware file
 		static FirmwareFile File(string hash, string recommendedName, string descr)
 		{
+			string hashfix = hash.ToUpperInvariant();
+
 			var ff = new FirmwareFile
 				{
-					hash = hash,
+					hash = hashfix,
 					recommendedName = recommendedName,
 					descr = descr
 				};
 			FirmwareFiles.Add(ff);
-			FirmwareFilesByHash[hash] = ff;
+			FirmwareFilesByHash[hashfix] = ff;
 			return ff;
 		}
 
@@ -189,9 +194,17 @@ namespace BizHawk.Emulation.Common
 				(from fr in FirmwareRecords
 				 where fr.firmwareId == firmwareId
 				 && fr.systemId == sysId
-				 select fr).First();
+				 select fr);
 
-			return found;
+			try
+			{
+				return found.First();
+			}
+			catch (InvalidOperationException)
+			{
+				// list is empty;
+				return null;
+			}
 		}
 
 	} //static class FirmwareDatabase
diff --git a/BizHawk.Emulation.Cores/Consoles/Sega/gpgx/GPGX.cs b/BizHawk.Emulation.Cores/Consoles/Sega/gpgx/GPGX.cs
index 8848cac8f2..587e824671 100644
--- a/BizHawk.Emulation.Cores/Consoles/Sega/gpgx/GPGX.cs
+++ b/BizHawk.Emulation.Cores/Consoles/Sega/gpgx/GPGX.cs
@@ -56,6 +56,7 @@ namespace BizHawk.Emulation.Cores.Consoles.Sega.gpgx
 				LoadCallback = new LibGPGX.load_archive_cb(load_archive);
 
 				this.romfile = romfile;
+				this.CD = CD;
 
 				LibGPGX.INPUT_SYSTEM system_a = LibGPGX.INPUT_SYSTEM.SYSTEM_NONE;
 				LibGPGX.INPUT_SYSTEM system_b = LibGPGX.INPUT_SYSTEM.SYSTEM_NONE;
diff --git a/BizHawk.Emulation.DiscSystem/Disc.ID.cs b/BizHawk.Emulation.DiscSystem/Disc.ID.cs
index cf438b9d48..ac57f40e20 100644
--- a/BizHawk.Emulation.DiscSystem/Disc.ID.cs
+++ b/BizHawk.Emulation.DiscSystem/Disc.ID.cs
@@ -34,7 +34,12 @@ namespace BizHawk.Emulation.DiscSystem
 		/// <summary>
 		/// Its not clear whether we can ever have enough info to ID a turboCD disc (we're using hashes)
 		/// </summary>
-		TurboCD
+		TurboCD,
+
+		/// <summary>
+		/// MegaDrive addon
+		/// </summary>
+		MegaCD
 	}
 
 	sealed public partial class Disc
@@ -48,6 +53,9 @@ namespace BizHawk.Emulation.DiscSystem
 			//sega doesnt put anything identifying in the cdfs volume info. but its consistent about putting its own header here in sector 0
 			if (DetectSegaSaturn()) return DiscType.SegaSaturn;
 
+			// not fully tested yet
+			if (DetectMegaCD()) return DiscType.MegaCD;
+
 			//we dont know how to detect TurboCD.
 			//an emulator frontend will likely just guess TurboCD if the disc is UnknownFormat
 
@@ -72,12 +80,25 @@ namespace BizHawk.Emulation.DiscSystem
 		/// This is reasonable approach to ID saturn.
 		/// </summary>
 		bool DetectSegaSaturn()
+		{
+			return StringAt("SEGA SEGASATURN", 0);
+		}
+
+		/// <summary>
+		/// probably wrong
+		/// </summary>
+		bool DetectMegaCD()
+		{
+			return StringAt("SEGADISCSYSTEM", 0) || StringAt("SEGADISCSYSTEM", 16);
+		}
+
+		private bool StringAt(string s, int n)
 		{
 			byte[] data = new byte[2048];
 			ReadLBA_2048(0, data, 0);
-			byte[] cmp = System.Text.Encoding.ASCII.GetBytes("SEGA SEGASATURN");
-			byte[] cmp2 = new byte[15];
-			Buffer.BlockCopy(data, 0, cmp2, 0, 15);
+			byte[] cmp = System.Text.Encoding.ASCII.GetBytes(s);
+			byte[] cmp2 = new byte[cmp.Length];
+			Buffer.BlockCopy(data, n, cmp2, 0, cmp.Length);
 			return System.Linq.Enumerable.SequenceEqual(cmp, cmp2);
 		}
 	}
diff --git a/genplus-gx/core/cd_hw/cdd.c b/genplus-gx/core/cd_hw/cdd.c
index dca3dac759..12c0f9f55e 100644
--- a/genplus-gx/core/cd_hw/cdd.c
+++ b/genplus-gx/core/cd_hw/cdd.c
@@ -238,7 +238,6 @@ void cdd_read_data(uint8 *dst)
 
 void cdd_read_audio(unsigned int samples)
 {
-/*
   // previous audio outputs //
   int16 l = cdd.audio[0];
   int16 r = cdd.audio[1];
@@ -247,7 +246,7 @@ void cdd_read_audio(unsigned int samples)
   samples = blip_clocks_needed(blip[0], samples);
 
   // audio track playing ? //
-  if (!scd.regs[0x36>>1].byte.h && cdd.toc.tracks[cdd.index].fd)
+  if (0) // (!scd.regs[0x36>>1].byte.h && cdd.toc.tracks[cdd.index].fd)
   {
     int i, mul, delta;
 
@@ -264,7 +263,7 @@ void cdd_read_audio(unsigned int samples)
 #else
       uint8 *ptr = cdc.ram;
 #endif
-      fread(cdc.ram, 1, samples * 4, cdd.toc.tracks[cdd.index].fd);
+      //fread(cdc.ram, 1, samples * 4, cdd.toc.tracks[cdd.index].fd);
 
       // process 16-bit (little-endian) stereo samples //
       for (i=0; i<samples; i++)
@@ -335,7 +334,6 @@ void cdd_read_audio(unsigned int samples)
   // end of Blip Buffer timeframe //
   blip_end_frame(blip[0], samples);
   blip_end_frame(blip[1], samples);
-*/
 }
 
 
diff --git a/output/dll/libgenplusgx.dll b/output/dll/libgenplusgx.dll
index c4a751af4c..91fde44270 100644
Binary files a/output/dll/libgenplusgx.dll and b/output/dll/libgenplusgx.dll differ