diff --git a/src/BizHawk.Emulation.Cores/Arcades/MAME/LibMAME.cs b/src/BizHawk.Emulation.Cores/Arcades/MAME/LibMAME.cs
index 3321bc885a..bb624ff84f 100644
--- a/src/BizHawk.Emulation.Cores/Arcades/MAME/LibMAME.cs
+++ b/src/BizHawk.Emulation.Cores/Arcades/MAME/LibMAME.cs
@@ -8,6 +8,7 @@ namespace BizHawk.Emulation.Cores.Arcades.MAME
 		internal const string dll = "libmamearcade.dll"; // libmamearcade.dll libpacshd.dll
 		private const CallingConvention cc = CallingConvention.Cdecl;
 
+		// enums
 		public enum OutputChannel
 		{
 			ERROR, WARNING, INFO, DEBUG, VERBOSE, LOG, COUNT
@@ -18,11 +19,13 @@ namespace BizHawk.Emulation.Cores.Arcades.MAME
 			NONE, NOT_FOUND, ILLEGAL_REGISTRATIONS, INVALID_HEADER, READ_ERROR, WRITE_ERROR, DISABLED
 		}
 
+		// constants
 		public const int ROMENTRYTYPE_SYSTEM_BIOS = 9;
 		public const int ROMENTRYTYPE_DEFAULT_BIOS = 10;
 		public const int ROMENTRY_TYPEMASK = 15;
 		public const int BIOS_INDEX = 24;
 		public const int BIOS_FIRST = 1;
+		public const string BIOS_LUA_CODE = "bios";
 
 		// main launcher
 		[DllImport(dll, CallingConvention = cc)]
diff --git a/src/BizHawk.Emulation.Cores/Arcades/MAME/MAME.ISettable.cs b/src/BizHawk.Emulation.Cores/Arcades/MAME/MAME.ISettable.cs
index 0e8cdd46dc..1634c5ea7b 100644
--- a/src/BizHawk.Emulation.Cores/Arcades/MAME/MAME.ISettable.cs
+++ b/src/BizHawk.Emulation.Cores/Arcades/MAME/MAME.ISettable.cs
@@ -86,13 +86,73 @@ namespace BizHawk.Emulation.Cores.Arcades.MAME
 			{
 				DriverSetting s = CurrentDriverSettings.SingleOrDefault(s => s.LookupKey == setting.Key);
 
-				if (s != null)
+				if (s != null && s.Type == SettingType.DIPSWITCH)
 				{
 					LibMAME.mame_lua_execute($"{ s.LuaCode }.user_value = { setting.Value }");
 				}
 			}
 		}
 
+		private void GetROMsInfo()
+		{
+			string ROMsInfo = MameGetString(MAMELuaCommand.GetROMsInfo);
+			string[] ROMs = ROMsInfo.Split(new char[] { ';' }, StringSplitOptions.RemoveEmptyEntries);
+			string tempDefault = "";
+
+			DriverSetting setting = new DriverSetting()
+			{
+				Name = "BIOS",
+				GameName = _gameShortName,
+				LuaCode = LibMAME.BIOS_LUA_CODE,
+				Type = SettingType.BIOS
+			};
+
+			foreach (string ROM in ROMs)
+			{
+				if (ROM != string.Empty)
+				{
+					string[] substrings = ROM.Split('~');
+					string name = substrings[0];
+					string hashdata = substrings[1];
+					long flags = long.Parse(substrings[2]);
+
+					if ((flags & LibMAME.ROMENTRY_TYPEMASK) == LibMAME.ROMENTRYTYPE_SYSTEM_BIOS
+						|| (flags & LibMAME.ROMENTRY_TYPEMASK) == LibMAME.ROMENTRYTYPE_DEFAULT_BIOS)
+					{
+						setting.Options.Add(name, hashdata);
+
+						// if no bios is explicitly marked as default
+						// mame uses the first one in the list
+						// and its index is reflected in the flags (ROM_BIOSFLAGSMASK)
+						if ((flags >> LibMAME.BIOS_INDEX) == LibMAME.BIOS_FIRST)
+						{
+							tempDefault = name;
+						}
+
+						if ((flags & LibMAME.ROMENTRY_TYPEMASK) == LibMAME.ROMENTRYTYPE_DEFAULT_BIOS)
+						{
+							setting.DefaultValue = name;
+						}
+					}
+					else
+					{
+						hashdata = hashdata.Replace("R", " CRC:").Replace("S", " SHA:");
+						_romHashes.Add(name, hashdata);
+					}
+				}
+			}
+
+			if (setting.Options.Count > 0)
+			{
+				if (setting.DefaultValue == null)
+				{
+					setting.DefaultValue = tempDefault;
+				}
+
+				CurrentDriverSettings.Add(setting);
+			}
+		}
+
 		public class DriverSetting
 		{
 			public string Name { get; set; }
@@ -101,7 +161,7 @@ namespace BizHawk.Emulation.Cores.Arcades.MAME
 			public string DefaultValue { get; set; }
 			public SettingType Type { get; set; }
 			public SortedDictionary<string, string> Options { get; set; }
-			public string LookupKey => $"[{ GameName }] { LuaCode }";
+			public string LookupKey => MAMELuaCommand.MakeLookupKey(GameName, LuaCode);
 
 			public DriverSetting()
 			{
diff --git a/src/BizHawk.Emulation.Cores/Arcades/MAME/MAME.cs b/src/BizHawk.Emulation.Cores/Arcades/MAME/MAME.cs
index 50bc12591a..cb825cbc50 100644
--- a/src/BizHawk.Emulation.Cores/Arcades/MAME/MAME.cs
+++ b/src/BizHawk.Emulation.Cores/Arcades/MAME/MAME.cs
@@ -79,6 +79,7 @@ using System.Diagnostics;
 using System.Linq;
 using BizHawk.Common;
 using BizHawk.Emulation.Common;
+using System.Collections.Generic;
 
 namespace BizHawk.Emulation.Cores.Arcades.MAME
 {
@@ -137,7 +138,7 @@ namespace BizHawk.Emulation.Cores.Arcades.MAME
 			LibMAME.mame_set_log_callback(_logCallback);
 
 			// https://docs.mamedev.org/commandline/commandline-index.html
-			string[] args =
+			List<string> args = new List<string>
 			{
 				 "mame"                                 // dummy, internally discarded by index, so has to go first
 				, _gameFileName                         // no dash for rom names
@@ -164,7 +165,14 @@ namespace BizHawk.Emulation.Cores.Arcades.MAME
 			//	, "-debug"                              // launch mame debugger (because we can)
 			};
 
-			LibMAME.mame_launch(args.Length, args);
+			if (_syncSettings.DriverSettings.TryGetValue(
+				MAMELuaCommand.MakeLookupKey(_gameFileName.Split('.')[0], LibMAME.BIOS_LUA_CODE),
+				out string value))
+			{
+				args.AddRange(new List<string>{ "-bios", value });
+			}
+
+			LibMAME.mame_launch(args.Count, args.ToArray());
 		}
 
 		private static string MameGetString(string command)
@@ -312,66 +320,6 @@ namespace BizHawk.Emulation.Cores.Arcades.MAME
 			}
 		}
 
-		private void GetROMsInfo()
-		{
-			string ROMsInfo = MameGetString(MAMELuaCommand.GetROMsInfo);
-			string[] ROMs = ROMsInfo.Split(new char[] { ';' }, StringSplitOptions.RemoveEmptyEntries);
-			string tempDefault = "";
-
-			DriverSetting setting = new DriverSetting()
-			{
-				Name = "BIOS",
-				GameName = _gameShortName,
-				LuaCode = "bios",
-				Type = SettingType.BIOS
-			};
-
-			foreach (string ROM in ROMs)
-			{
-				if (ROM != string.Empty)
-				{
-					string[] substrings = ROM.Split('~');
-					string name = substrings[0];
-					string hashdata = substrings[1];
-					long flags = long.Parse(substrings[2]);
-
-					if ((flags & LibMAME.ROMENTRY_TYPEMASK) == LibMAME.ROMENTRYTYPE_SYSTEM_BIOS
-						|| (flags & LibMAME.ROMENTRY_TYPEMASK) == LibMAME.ROMENTRYTYPE_DEFAULT_BIOS)
-					{
-						setting.Options.Add(name, hashdata);
-
-						// if no bios is explicitly marked as default
-						// mame uses the first one in the list
-						// and its index is reflected in the flags (ROM_BIOSFLAGSMASK)
-						if ((flags >> LibMAME.BIOS_INDEX) == LibMAME.BIOS_FIRST)
-						{
-							tempDefault = name;
-						}
-
-						if ((flags & LibMAME.ROMENTRY_TYPEMASK) == LibMAME.ROMENTRYTYPE_DEFAULT_BIOS)
-						{
-							setting.DefaultValue = name;
-						}
-					}
-					else
-					{
-						hashdata = hashdata.Replace("R", " CRC:").Replace("S", " SHA:");
-						_romHashes.Add(name, hashdata);
-					}
-				}
-			}
-
-			if (setting.Options.Count > 0)
-			{
-				if (setting.DefaultValue == null)
-				{
-					setting.DefaultValue = tempDefault;
-				}
-
-				CurrentDriverSettings.Add(setting);
-			}
-		}
-
 		private class MAMELuaCommand
 		{
 			// commands
@@ -447,6 +395,8 @@ namespace BizHawk.Emulation.Cores.Arcades.MAME
 				"table.sort(final) " +
 				"return table.concat(final)";
 
+			public static string MakeLookupKey(string gameName, string luaCode) =>
+				$"[{ gameName }] { luaCode }";
 			public static string InputField(string tag, string fieldName) =>
 				$"manager.machine.ioport.ports[\"{ tag }\"].fields[\"{ fieldName }\"]";
 			public static string GetDIPSwitchFields(string tag) =>