diff --git a/src/BizHawk.Emulation.Common/Database/FirmwareDatabase.cs b/src/BizHawk.Emulation.Common/Database/FirmwareDatabase.cs
index 133539eb2f..b5472ef955 100644
--- a/src/BizHawk.Emulation.Common/Database/FirmwareDatabase.cs
+++ b/src/BizHawk.Emulation.Common/Database/FirmwareDatabase.cs
@@ -280,6 +280,8 @@ namespace BizHawk.Emulation.Common
 			var jp_mcd_beta = File("F30D109D1C2F7C9FEAF38600C65834261DB73D1F", 131072, "MCD_jp_beta.bin", "Mega CD JP (Beta)");
 			var eu_mcd_221 = File("9DE4EDA59F544DB2D5FD7E6514601F7B648D8EB4", 131072, "MCD_eu_221.bin", "Mega CD EU (v2.21)");
 
+			FirmwareAndOption("1C470A9A8D0B211C5FEEA1C1C2376AA1F7934B16", 4096, "GEN", "TMSS", "TMSS.md", "Mega Drive TMSS Boot Rom (Japan)");
+
 			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)");
diff --git a/src/BizHawk.Emulation.Cores/Consoles/Sega/gpgx64/GPGX.IDebuggable.cs b/src/BizHawk.Emulation.Cores/Consoles/Sega/gpgx64/GPGX.IDebuggable.cs
index 6647386c46..1d201d55fe 100644
--- a/src/BizHawk.Emulation.Cores/Consoles/Sega/gpgx64/GPGX.IDebuggable.cs
+++ b/src/BizHawk.Emulation.Cores/Consoles/Sega/gpgx64/GPGX.IDebuggable.cs
@@ -11,20 +11,19 @@ namespace BizHawk.Emulation.Cores.Consoles.Sega.gpgx
 	{
 		public IDictionary<string, RegisterValue> GetCpuFlagsAndRegisters()
 		{
-			LibGPGX.RegisterInfo[] regs = new LibGPGX.RegisterInfo[Core.gpgx_getmaxnumregs()];
-
-			int n = Core.gpgx_getregs(regs);
+			var regs = new LibGPGX.RegisterInfo[Core.gpgx_getmaxnumregs()];
+			var n = Core.gpgx_getregs(regs);
 			if (n > regs.Length)
 				throw new InvalidOperationException("A buffer overrun has occured!");
 			var ret = new Dictionary<string, RegisterValue>();
 			using (_elf.EnterExit())
 			{
-				for (int i = 0; i < n; i++)
+				for (var i = 0; i < n; i++)
 				{
 					// el hacko
-					string name = Marshal.PtrToStringAnsi(regs[i].Name);
+					var name = Marshal.PtrToStringAnsi(regs[i].Name);
 					byte size = 32;
-					if (name.Contains("68K SR") || name.StartsWithOrdinal("Z80"))
+					if (name!.Contains("68K SR") || name.StartsWithOrdinal("Z80"))
 						size = 16;
 
 					ret[name] = new RegisterValue((ulong)regs[i].Value, size);
@@ -40,17 +39,28 @@ namespace BizHawk.Emulation.Cores.Consoles.Sega.gpgx
 			throw new NotImplementedException();
 		}
 
-		public IMemoryCallbackSystem MemoryCallbacks => _memoryCallbacks;
+		public IMemoryCallbackSystem MemoryCallbacks
+		{
+			get
+			{
+				if (SystemId == VSystemID.Raw.GEN)
+				{
+					return _memoryCallbacks;
+				}
 
-		public bool CanStep(StepType type) { return false; }
+				throw new NotImplementedException();
+			}
+		}
+
+		public bool CanStep(StepType type) => false;
 
 		[FeatureNotImplemented]
-		public void Step(StepType type) { throw new NotImplementedException(); }
+		public void Step(StepType type) => throw new NotImplementedException();
 
 		[FeatureNotImplemented]
 		public long TotalExecutedCycles => throw new NotImplementedException();
 
-		private readonly MemoryCallbackSystem _memoryCallbacks = new MemoryCallbackSystem(new[] { "M68K BUS" });
+		private readonly MemoryCallbackSystem _memoryCallbacks = new(new[] { "M68K BUS" });
 
 		private LibGPGX.mem_cb ExecCallback;
 		private LibGPGX.mem_cb ReadCallback;
@@ -59,30 +69,30 @@ namespace BizHawk.Emulation.Cores.Consoles.Sega.gpgx
 
 		private void InitMemCallbacks()
 		{
-			ExecCallback = new LibGPGX.mem_cb(a =>
+			ExecCallback = a =>
 			{
 				if (MemoryCallbacks.HasExecutes)
 				{
-					uint flags = (uint)MemoryCallbackFlags.AccessExecute;
+					const uint flags = (uint)MemoryCallbackFlags.AccessExecute;
 					MemoryCallbacks.CallMemoryCallbacks(a, 0, flags, "M68K BUS");
 				}
-			});
-			ReadCallback = new LibGPGX.mem_cb(a =>
+			};
+			ReadCallback = a =>
 			{
 				if (MemoryCallbacks.HasReads)
 				{
-					uint flags = (uint)MemoryCallbackFlags.AccessRead;
+					const uint flags = (uint)MemoryCallbackFlags.AccessRead;
 					MemoryCallbacks.CallMemoryCallbacks(a, 0, flags, "M68K BUS");
 				}
-			});
-			WriteCallback = new LibGPGX.mem_cb(a =>
+			};
+			WriteCallback = a =>
 			{
 				if (MemoryCallbacks.HasWrites)
 				{
-					uint flags = (uint)MemoryCallbackFlags.AccessWrite;
+					const uint flags = (uint)MemoryCallbackFlags.AccessWrite;
 					MemoryCallbacks.CallMemoryCallbacks(a, 0, flags, "M68K BUS");
 				}
-			});
+			};
 			_memoryCallbacks.ActiveChanged += RefreshMemCallbacks;
 		}
 
diff --git a/src/BizHawk.Emulation.Cores/Consoles/Sega/gpgx64/GPGX.IMemoryDomains.cs b/src/BizHawk.Emulation.Cores/Consoles/Sega/gpgx64/GPGX.IMemoryDomains.cs
index 49f16344e8..5bc9074045 100644
--- a/src/BizHawk.Emulation.Cores/Consoles/Sega/gpgx64/GPGX.IMemoryDomains.cs
+++ b/src/BizHawk.Emulation.Cores/Consoles/Sega/gpgx64/GPGX.IMemoryDomains.cs
@@ -25,7 +25,10 @@ namespace BizHawk.Emulation.Cores.Consoles.Sega.gpgx
 						continue;
 					var name = Marshal.PtrToStringAnsi(pName)!;
 
-					var endian = name == "Z80 RAM"
+					// typically Genesis domains will be 2 bytes large (and thus big endian and byteswapped)
+					var oneByteWidth = name is "Z80 RAM" or "Main RAM" or "ROM" or "Cart (Volatile) RAM" or "SRAM";
+
+					var endian = oneByteWidth
 							? MemoryDomain.Endian.Little
 							: MemoryDomain.Endian.Big;
 
@@ -33,44 +36,86 @@ namespace BizHawk.Emulation.Cores.Consoles.Sega.gpgx
 					{
 						// vram pokes need to go through hook which invalidates cached tiles
 						var p = (byte*)area;
-						mm.Add(new MemoryDomainDelegate(name, size, MemoryDomain.Endian.Big,
-							addr =>
-							{
-								if (addr is < 0 or > 0xFFFF) throw new ArgumentOutOfRangeException(paramName: nameof(addr), addr, message: "address out of range");
-								using (_elf.EnterExit())
-									return p![addr ^ 1];
-							},
-							(addr, val) =>
-							{
-								if (addr is < 0 or > 0xFFFF) throw new ArgumentOutOfRangeException(paramName: nameof(addr), addr, message: "address out of range");
-								Core.gpgx_poke_vram((int)addr ^ 1, val);
-							},
-							wordSize: 2));
+						if (SystemId == VSystemID.Raw.GEN)
+						{
+							// Genesis has more VRAM, and GPGX byteswaps it
+							mm.Add(new MemoryDomainDelegate(name, size, MemoryDomain.Endian.Big,
+								addr =>
+								{
+									if (addr is < 0 or > 0xFFFF) throw new ArgumentOutOfRangeException(paramName: nameof(addr), addr, message: "address out of range");
+									using (_elf.EnterExit())
+										return p![addr ^ 1];
+								},
+								(addr, val) =>
+								{
+									if (addr is < 0 or > 0xFFFF) throw new ArgumentOutOfRangeException(paramName: nameof(addr), addr, message: "address out of range");
+									Core.gpgx_poke_vram((int)addr ^ 1, val);
+								},
+								wordSize: 1));
+						}
+						else
+						{
+							mm.Add(new MemoryDomainDelegate(name, size, MemoryDomain.Endian.Big,
+								addr =>
+								{
+									if (addr is < 0 or > 0x3FFF) throw new ArgumentOutOfRangeException(paramName: nameof(addr), addr, message: "address out of range");
+									using (_elf.EnterExit())
+										return p![addr];
+								},
+								(addr, val) =>
+								{
+									if (addr is < 0 or > 0x3FFF) throw new ArgumentOutOfRangeException(paramName: nameof(addr), addr, message: "address out of range");
+									Core.gpgx_poke_vram((int)addr, val);
+								},
+								wordSize: 1));
+						}
 					}
 					else if (name == "CRAM")
 					{
-						// CRAM in the core is internally a different format than what it is natively
-						// this internal format isn't really useful, so let's convert it back
 						var p = (byte*)area;
-						mm.Add(new MemoryDomainDelegate(name, size, MemoryDomain.Endian.Big,
-							addr =>
-							{
-								if (addr is < 0 or > 0x7F) throw new ArgumentOutOfRangeException(paramName: nameof(addr), addr, message: "address out of range");
-								using (_elf.EnterExit())
+						if (SystemId == VSystemID.Raw.GEN)
+						{
+							// CRAM for Genesis in the core is internally a different format than what it is natively
+							// this internal format isn't really useful, so let's convert it back
+							mm.Add(new MemoryDomainDelegate(name, size, MemoryDomain.Endian.Big,
+								addr =>
 								{
-									var c = *(ushort*)&p![addr & ~1];
-									c = (ushort)(((c & 0x1C0) << 3) | ((c & 0x038) << 2) | ((c & 0x007) << 1));
-									return (byte)((addr & 1) != 0 ? c & 0xFF : c >> 8);
-								}
-							},
-							(addr, val) =>
-							{
-								if (addr is < 0 or > 0x7F) throw new ArgumentOutOfRangeException(paramName: nameof(addr), addr, message: "address out of range");
-								Core.gpgx_poke_cram((int)addr, val);
-							},
-							wordSize: 2));
+									if (addr is < 0 or > 0x7F) throw new ArgumentOutOfRangeException(paramName: nameof(addr), addr, message: "address out of range");
+									using (_elf.EnterExit())
+									{
+										var c = *(ushort*)&p![addr & ~1];
+										c = (ushort)(((c & 0x1C0) << 3) | ((c & 0x038) << 2) | ((c & 0x007) << 1));
+										return (byte)((addr & 1) != 0 ? c & 0xFF : c >> 8);
+									}
+								},
+								(addr, val) =>
+								{
+									if (addr is < 0 or > 0x7F) throw new ArgumentOutOfRangeException(paramName: nameof(addr), addr, message: "address out of range");
+									Core.gpgx_poke_cram((int)addr, val);
+								},
+								wordSize: 2));
+						}
+						else
+						{
+							mm.Add(new MemoryDomainDelegate(name, size, MemoryDomain.Endian.Big,
+								addr =>
+								{
+									if (addr is < 0 or > 0x3F) throw new ArgumentOutOfRangeException(paramName: nameof(addr), addr, message: "address out of range");
+									using (_elf.EnterExit())
+									{
+										var c = *(ushort*)&p![addr & ~1];
+										return (byte)((addr & 1) != 0 ? c & 0xFF : c >> 8);
+									}
+								},
+								(addr, val) =>
+								{
+									if (addr is < 0 or > 0x3F) throw new ArgumentOutOfRangeException(paramName: nameof(addr), addr, message: "address out of range");
+									Core.gpgx_poke_cram((int)addr, val);
+								},
+								wordSize: 2));
+						}
 					}
-					else if (name.Contains("Z80"))
+					else if (oneByteWidth)
 					{
 						mm.Add(new MemoryDomainIntPtrMonitor(name, endian, area, size, true, 1, _elf));
 					}
@@ -79,44 +124,64 @@ namespace BizHawk.Emulation.Cores.Consoles.Sega.gpgx
 						mm.Add(new MemoryDomainIntPtrSwap16Monitor(name, endian, area, size, true, _elf));
 					}
 				}
-				var m68Bus = new MemoryDomainDelegate("M68K BUS", 0x1000000, MemoryDomain.Endian.Big,
-					addr =>
-					{
-						var a = (uint)addr;
-						if (a > 0xFFFFFF) throw new ArgumentOutOfRangeException(paramName: nameof(addr), a, message: "address out of range");
-						return Core.gpgx_peek_m68k_bus(a);
-					},
-					(addr, val) =>
-					{
-						var a = (uint)addr;
-						if (a > 0xFFFFFF) throw new ArgumentOutOfRangeException(paramName: nameof(addr), a, message: "address out of range");
-						Core.gpgx_write_m68k_bus(a, val);
-					}, 2);
 
-				mm.Add(m68Bus);
-
-				if (IsMegaCD)
+				MemoryDomain systemBus;
+				if (SystemId == VSystemID.Raw.GEN)
 				{
-					var s68Bus = new MemoryDomainDelegate("S68K BUS", 0x1000000, MemoryDomain.Endian.Big,
-					addr =>
-					{
-						var a = (uint)addr;
-						if (a > 0xFFFFFF) throw new ArgumentOutOfRangeException(paramName: nameof(addr), a, message: "address out of range");
-						return Core.gpgx_peek_s68k_bus(a);
-					},
-					(addr, val) =>
-					{
-						var a = (uint)addr;
-						if (a > 0xFFFFFF) throw new ArgumentOutOfRangeException(paramName: nameof(addr), a, message: "address out of range");
-						Core.gpgx_write_s68k_bus(a, val);
-					}, 2);
+					systemBus = new MemoryDomainDelegate("M68K BUS", 0x1000000, MemoryDomain.Endian.Big,
+						addr =>
+						{
+							var a = (uint)addr;
+							if (a > 0xFFFFFF) throw new ArgumentOutOfRangeException(paramName: nameof(addr), a, message: "address out of range");
+							return Core.gpgx_peek_m68k_bus(a);
+						},
+						(addr, val) =>
+						{
+							var a = (uint)addr;
+							if (a > 0xFFFFFF) throw new ArgumentOutOfRangeException(paramName: nameof(addr), a, message: "address out of range");
+							Core.gpgx_write_m68k_bus(a, val);
+						}, 2);
 
+					mm.Add(systemBus);
 
-					mm.Add(s68Bus);
+					if (IsMegaCD)
+					{
+						var s68Bus = new MemoryDomainDelegate("S68K BUS", 0x1000000, MemoryDomain.Endian.Big,
+							addr =>
+							{
+								var a = (uint)addr;
+								if (a > 0xFFFFFF) throw new ArgumentOutOfRangeException(paramName: nameof(addr), a, message: "address out of range");
+								return Core.gpgx_peek_s68k_bus(a);
+							},
+							(addr, val) =>
+							{
+								var a = (uint)addr;
+								if (a > 0xFFFFFF) throw new ArgumentOutOfRangeException(paramName: nameof(addr), a, message: "address out of range");
+								Core.gpgx_write_s68k_bus(a, val);
+							}, 2);
+
+						mm.Add(s68Bus);
+					}
+				}
+				else
+				{
+					systemBus = new MemoryDomainDelegate("Z80 BUS", 0x10000, MemoryDomain.Endian.Little,
+						addr =>
+						{
+							var a = (uint)addr;
+							if (a > 0xFFFF) throw new ArgumentOutOfRangeException(paramName: nameof(addr), a, message: "address out of range");
+							return Core.gpgx_peek_z80_bus(a);
+						},
+						(addr, val) =>
+						{
+							var a = (uint)addr;
+							if (a > 0xFFFF) throw new ArgumentOutOfRangeException(paramName: nameof(addr), a, message: "address out of range");
+							Core.gpgx_write_z80_bus(a, val);
+						}, 1);
 				}
-				mm.Add(_elf.GetPagesDomain());
 
-				_memoryDomains = new MemoryDomainList(mm) { SystemBus = m68Bus };
+				mm.Add(_elf.GetPagesDomain());
+				_memoryDomains = new MemoryDomainList(mm) { SystemBus = systemBus };
 				((BasicServiceProvider) ServiceProvider).Register(_memoryDomains);
 			}
 		}
diff --git a/src/BizHawk.Emulation.Cores/Consoles/Sega/gpgx64/GPGX.ISettable.cs b/src/BizHawk.Emulation.Cores/Consoles/Sega/gpgx64/GPGX.ISettable.cs
index 9616c11485..540eeb3849 100644
--- a/src/BizHawk.Emulation.Cores/Consoles/Sega/gpgx64/GPGX.ISettable.cs
+++ b/src/BizHawk.Emulation.Cores/Consoles/Sega/gpgx64/GPGX.ISettable.cs
@@ -263,7 +263,7 @@ namespace BizHawk.Emulation.Cores.Consoles.Sega.gpgx
 			[DefaultValue(LibGPGX.Region.Autodetect)]
 			public LibGPGX.Region Region { get; set; }
 
-			[DisplayName("[SMS/GG] Load BIOS")]
+			[DisplayName("Load BIOS")]
 			[Description("Indicates whether to load the system BIOS rom.")]
 			[DefaultValue(false)]
 			public bool LoadBIOS { get; set; }
diff --git a/src/BizHawk.Emulation.Cores/Consoles/Sega/gpgx64/GPGX.cs b/src/BizHawk.Emulation.Cores/Consoles/Sega/gpgx64/GPGX.cs
index 664e26637d..058aeebf04 100644
--- a/src/BizHawk.Emulation.Cores/Consoles/Sega/gpgx64/GPGX.cs
+++ b/src/BizHawk.Emulation.Cores/Consoles/Sega/gpgx64/GPGX.cs
@@ -104,6 +104,14 @@ namespace BizHawk.Emulation.Cores.Consoles.Sega.gpgx
 				var initSettings = _syncSettings.GetNativeSettings(lp.Game);
 				var initResult = Core.gpgx_init(romExtension, LoadCallback, ref initSettings);
 
+				// if a firmware request failed and we're recording a movie, fail now
+				// we should do this as to enforce the sync settings of the movie
+				// init might still work fine, so don't throw for more casual users
+				if (_firmwareRequestFailed && lp.DeterministicEmulationRequested)
+				{
+					throw new MissingFirmwareException("A GPGX firmware request failed in deterministic mode.");
+				}
+
 				if (!initResult)
 				{
 					throw new Exception($"{nameof(Core.gpgx_init)}() failed");
@@ -183,6 +191,7 @@ namespace BizHawk.Emulation.Cores.Consoles.Sega.gpgx
 		private bool _disposed = false;
 
 		private LibGPGX.load_archive_cb LoadCallback;
+		private bool _firmwareRequestFailed;
 
 		private readonly LibGPGX.InputData input = new LibGPGX.InputData();
 
@@ -252,6 +261,7 @@ namespace BizHawk.Emulation.Cores.Consoles.Sega.gpgx
 
  				FirmwareID? firmwareID = filename switch
  				{
+					"MD_BIOS" => new(system: VSystemID.Raw.GEN, firmware: "TMSS"),
  					"CD_BIOS_EU" => new(system: VSystemID.Raw.GEN, firmware: "CD_BIOS_EU"),
  					"CD_BIOS_JP" => new(system: VSystemID.Raw.GEN, firmware: "CD_BIOS_JP"),
  					"CD_BIOS_US" => new(system: VSystemID.Raw.GEN, firmware: "CD_BIOS_US"),
@@ -268,6 +278,7 @@ namespace BizHawk.Emulation.Cores.Consoles.Sega.gpgx
 					srcdata = CoreComm.CoreFileProvider.GetFirmware(firmwareID.Value, "GPGX firmwares are usually required.");
 					if (srcdata == null)
 					{
+						_firmwareRequestFailed = true;
 						Console.WriteLine($"Frontend couldn't satisfy firmware request {firmwareID}");
 						return 0;
 					}
@@ -407,7 +418,7 @@ namespace BizHawk.Emulation.Cores.Consoles.Sega.gpgx
 		{
 			private readonly IMonitor _m;
 
-			public VDPView(LibGPGX.VDPView v, IMonitor m)
+			public VDPView(in LibGPGX.VDPView v, IMonitor m)
 			{
 				_m = m;
 				VRAM = v.VRAM;
@@ -439,12 +450,11 @@ namespace BizHawk.Emulation.Cores.Consoles.Sega.gpgx
 
 		public VDPView UpdateVDPViewContext()
 		{
-			var v = new LibGPGX.VDPView();
-			Core.gpgx_get_vdp_view(v);
+			Core.gpgx_get_vdp_view(out var v);
 			Core.gpgx_flush_vram(); // fully regenerate internal caches as needed
-			return new VDPView(v, _elf);
+			return new VDPView(in v, _elf);
 		}
-		
+
 		public int AddDeepFreezeValue(int address, byte value)
 		{
 			return Core.gpgx_add_deepfreeze_list_entry(address, value);
diff --git a/src/BizHawk.Emulation.Cores/Consoles/Sega/gpgx64/LibGPGX.cs b/src/BizHawk.Emulation.Cores/Consoles/Sega/gpgx64/LibGPGX.cs
index 24216f1c2f..f6780b9b57 100644
--- a/src/BizHawk.Emulation.Cores/Consoles/Sega/gpgx64/LibGPGX.cs
+++ b/src/BizHawk.Emulation.Cores/Consoles/Sega/gpgx64/LibGPGX.cs
@@ -98,6 +98,7 @@ namespace BizHawk.Emulation.Cores.Consoles.Sega.gpgx
 
 		[BizImport(CallingConvention.Cdecl, Compatibility = true)]
 		public abstract bool gpgx_get_control([Out]InputData dest, int bytes);
+
 		[BizImport(CallingConvention.Cdecl, Compatibility = true)]
 		public abstract bool gpgx_put_control([In]InputData src, int bytes);
 
@@ -331,7 +332,7 @@ namespace BizHawk.Emulation.Cores.Consoles.Sega.gpgx
 		public abstract void gpgx_set_cdd_callback(cd_read_cb cddcb);
 
 		[BizImport(CallingConvention.Cdecl, Compatibility = true)]
-		public abstract void gpgx_swap_disc(CDData toc);
+		public abstract void gpgx_swap_disc([In] CDData toc);
 
 		[StructLayout(LayoutKind.Sequential)]
 		public struct VDPNameTable
@@ -342,7 +343,7 @@ namespace BizHawk.Emulation.Cores.Consoles.Sega.gpgx
 		}
 
 		[StructLayout(LayoutKind.Sequential)]
-		public class VDPView
+		public struct VDPView
 		{
 			public IntPtr VRAM;
 			public IntPtr PatternCache;
@@ -352,8 +353,8 @@ namespace BizHawk.Emulation.Cores.Consoles.Sega.gpgx
 			public VDPNameTable NTW;
 		}
 
-		[BizImport(CallingConvention.Cdecl, Compatibility = true)]
-		public abstract void gpgx_get_vdp_view([Out] VDPView view);
+		[BizImport(CallingConvention.Cdecl)]
+		public abstract void gpgx_get_vdp_view(out VDPView view);
 
 		[BizImport(CallingConvention.Cdecl)]
 		public abstract void gpgx_poke_cram(int addr, byte value);
@@ -383,8 +384,8 @@ namespace BizHawk.Emulation.Cores.Consoles.Sega.gpgx
 		[BizImport(CallingConvention.Cdecl)]
 		public abstract int gpgx_getmaxnumregs();
 
-		[BizImport(CallingConvention.Cdecl, Compatibility = true)]
-		public abstract int gpgx_getregs([Out] RegisterInfo[] regs);
+		[BizImport(CallingConvention.Cdecl)]
+		public abstract int gpgx_getregs(RegisterInfo[] regs);
 
 		[Flags]
 		public enum DrawMask : int
@@ -398,15 +399,25 @@ namespace BizHawk.Emulation.Cores.Consoles.Sega.gpgx
 
 		[BizImport(CallingConvention.Cdecl)]
 		public abstract void gpgx_set_draw_mask(DrawMask mask);
+
 		[BizImport(CallingConvention.Cdecl)]
 		public abstract void gpgx_set_sprite_limit_enabled(bool enabled);
 
+		[BizImport(CallingConvention.Cdecl)]
+		public abstract void gpgx_write_z80_bus(uint addr, byte data);
+
 		[BizImport(CallingConvention.Cdecl)]
 		public abstract void gpgx_write_m68k_bus(uint addr, byte data);
+
 		[BizImport(CallingConvention.Cdecl)]
 		public abstract void gpgx_write_s68k_bus(uint addr, byte data);
+
+		[BizImport(CallingConvention.Cdecl)]
+		public abstract byte gpgx_peek_z80_bus(uint addr);
+
 		[BizImport(CallingConvention.Cdecl)]
 		public abstract byte gpgx_peek_m68k_bus(uint addr);
+
 		[BizImport(CallingConvention.Cdecl)]
 		public abstract byte gpgx_peek_s68k_bus(uint addr);
 	}