diff --git a/BizHawk.Emulation.Cores/BizHawk.Emulation.Cores.csproj b/BizHawk.Emulation.Cores/BizHawk.Emulation.Cores.csproj
index 25dca6a906..663d0ecca5 100644
--- a/BizHawk.Emulation.Cores/BizHawk.Emulation.Cores.csproj
+++ b/BizHawk.Emulation.Cores/BizHawk.Emulation.Cores.csproj
@@ -738,7 +738,7 @@
       <DependentUpon>QuickNES.cs</DependentUpon>
     </Compile>
     <Compile Include="Consoles\Nintendo\QuickNES\QuickNES.ITraceable.cs">
-        <DependentUpon>QuickNES.cs</DependentUpon>
+      <DependentUpon>QuickNES.cs</DependentUpon>
     </Compile>
     <Compile Include="Consoles\Nintendo\QuickNES\QuickNES.IVideoProvider.cs">
       <DependentUpon>QuickNES.cs</DependentUpon>
@@ -770,6 +770,7 @@
     <Compile Include="Consoles\Sega\Genesis\Native68000\Musashi.cs" />
     <Compile Include="Consoles\Sega\gpgx\GenDbgHlp.cs" />
     <Compile Include="Consoles\Sega\gpgx\GPGX.cs" />
+    <Compile Include="Consoles\Sega\gpgx\GPGX.IDisassembler.cs" />
     <Compile Include="Consoles\Sega\gpgx\GPGXControlConverter.cs" />
     <Compile Include="Consoles\Sega\gpgx\LibGPGX.cs" />
     <Compile Include="Consoles\Sega\Saturn\FilePiping.cs" />
diff --git a/BizHawk.Emulation.Cores/Consoles/Sega/gpgx/GPGX.IDisassembler.cs b/BizHawk.Emulation.Cores/Consoles/Sega/gpgx/GPGX.IDisassembler.cs
new file mode 100644
index 0000000000..cb1e0043d8
--- /dev/null
+++ b/BizHawk.Emulation.Cores/Consoles/Sega/gpgx/GPGX.IDisassembler.cs
@@ -0,0 +1,45 @@
+using System.Collections.Generic;
+using BizHawk.Emulation.Common;
+using BizHawk.Emulation.Cores.Components.M68000;
+
+namespace BizHawk.Emulation.Cores.Consoles.Sega.gpgx
+{
+	public partial class GPGX : IDisassemblable
+	{
+		public string Cpu
+		{
+			get
+			{
+				return "M68000";
+			}
+			set
+			{
+			}
+		}
+
+		public string PCRegisterName
+		{
+			get { return "M68K PC"; }
+		}
+
+		public IEnumerable<string> AvailableCpus
+		{
+			get { yield return "M68000"; }
+		}
+
+		public string Disassemble(MemoryDomain m, uint addr, out int length)
+		{
+			_disassemblerInstance.ReadWord = (a) => (short)m.PeekWord(a, m.EndianType == MemoryDomain.Endian.Big);
+			_disassemblerInstance.ReadByte = (a) => (sbyte)m.PeekByte(a);
+			_disassemblerInstance.ReadLong = (a) => (int)m.PeekDWord(a, m.EndianType == MemoryDomain.Endian.Big);
+			var info = _disassemblerInstance.Disassemble((int)addr);
+
+			length = info.Length;
+
+			return info.ToString();
+		}
+
+		// TODO: refactor MC6800's disassembler to be a static call
+		private MC68000 _disassemblerInstance = new MC68000();
+	}
+}
diff --git a/BizHawk.Emulation.Cores/Consoles/Sega/gpgx/GPGX.cs b/BizHawk.Emulation.Cores/Consoles/Sega/gpgx/GPGX.cs
index 39726deff9..c5e7499d99 100644
--- a/BizHawk.Emulation.Cores/Consoles/Sega/gpgx/GPGX.cs
+++ b/BizHawk.Emulation.Cores/Consoles/Sega/gpgx/GPGX.cs
@@ -25,8 +25,8 @@ namespace BizHawk.Emulation.Cores.Consoles.Sega.gpgx
 		portedUrl: "https://code.google.com/p/genplus-gx/",
 		singleInstance: true
 		)]
-	public class GPGX : IEmulator, ISyncSoundProvider, IVideoProvider, ISaveRam, IStatable, IRegionable,
-		IInputPollable, IDebuggable, ISettable<GPGX.GPGXSettings, GPGX.GPGXSyncSettings>, IDriveLight, ICodeDataLogger
+	public partial class GPGX : IEmulator, ISyncSoundProvider, IVideoProvider, ISaveRam, IStatable, IRegionable,
+		IInputPollable, IDebuggable, ISettable<GPGX.GPGXSettings, GPGX.GPGXSyncSettings>, IDriveLight, ICodeDataLogger, IDisassemblable
 	{
 		static GPGX AttachedCore = null;
 
@@ -667,40 +667,53 @@ namespace BizHawk.Emulation.Cores.Consoles.Sega.gpgx
 					mm.Add(MemoryDomain.FromIntPtrSwap16(name, size, MemoryDomain.Endian.Big, area, writable: true, byteSize: byteSize));
 				}
 			}
-			mm.Add(new MemoryDomain("M68K BUS", 0x1000000, MemoryDomain.Endian.Big,
-				delegate(long addr)
+			var m68Bus = new MemoryDomain("M68K BUS", 0x1000000, MemoryDomain.Endian.Big,
+				delegate (long addr)
 				{
 					var a = (uint)addr;
 					if (a >= 0x1000000)
 						throw new ArgumentOutOfRangeException();
 					return LibGPGX.gpgx_peek_m68k_bus(a);
 				},
-				delegate(long addr, byte val)
+				delegate (long addr, byte val)
 				{
 					var a = (uint)addr;
 					if (a >= 0x1000000)
 						throw new ArgumentOutOfRangeException();
 					LibGPGX.gpgx_write_m68k_bus(a, val);
-				}, 2));
-			mm.Add(new MemoryDomain("S68K BUS", 0x1000000, MemoryDomain.Endian.Big,
-				delegate(long addr)
+				}, 2);
+
+			mm.Add(m68Bus);
+
+			var s68Bus = new MemoryDomain("S68K BUS", 0x1000000, MemoryDomain.Endian.Big,
+				delegate (long addr)
 				{
 					var a = (uint)addr;
 					if (a >= 0x1000000)
 						throw new ArgumentOutOfRangeException();
 					return LibGPGX.gpgx_peek_s68k_bus(a);
 				},
-				delegate(long addr, byte val)
+				delegate (long addr, byte val)
 				{
 					var a = (uint)addr;
 					if (a >= 0x1000000)
 						throw new ArgumentOutOfRangeException();
 					LibGPGX.gpgx_write_s68k_bus(a, val);
-				}, 2));
+				}, 2);
+
+			if (IsSegaCD)
+			{
+				mm.Add(s68Bus);
+			}
+
 			MemoryDomains = new MemoryDomainList(mm);
+			MemoryDomains.SystemBus = IsSegaCD ? s68Bus : m68Bus;
+
 			(ServiceProvider as BasicServiceProvider).Register<IMemoryDomains>(MemoryDomains);
 		}
 
+		public bool IsSegaCD { get { return CD != null; } }
+
 		public IDictionary<string, RegisterValue> GetCpuFlagsAndRegisters()
 		{
 			LibGPGX.RegisterInfo[] regs = new LibGPGX.RegisterInfo[LibGPGX.gpgx_getmaxnumregs()];