diff --git a/BizHawk.Emulation.Cores/Consoles/Sega/SMS/SMS.ICodeDataLogger.cs b/BizHawk.Emulation.Cores/Consoles/Sega/SMS/SMS.ICodeDataLogger.cs
index 199cfef58c..08d49d04ad 100644
--- a/BizHawk.Emulation.Cores/Consoles/Sega/SMS/SMS.ICodeDataLogger.cs
+++ b/BizHawk.Emulation.Cores/Consoles/Sega/SMS/SMS.ICodeDataLogger.cs
@@ -4,7 +4,7 @@ using BizHawk.Emulation.Common;
 
 namespace BizHawk.Emulation.Cores.Sega.MasterSystem
 {
-	public sealed partial class SMS : ICodeDataLogger
+	public partial class SMS : ICodeDataLogger
 	{
 		public void SetCDL(ICodeDataLog cdl)
 		{
diff --git a/BizHawk.Emulation.Cores/Consoles/Sega/SMS/SMS.IDebuggable.cs b/BizHawk.Emulation.Cores/Consoles/Sega/SMS/SMS.IDebuggable.cs
index 2f142e92da..c0043478f0 100644
--- a/BizHawk.Emulation.Cores/Consoles/Sega/SMS/SMS.IDebuggable.cs
+++ b/BizHawk.Emulation.Cores/Consoles/Sega/SMS/SMS.IDebuggable.cs
@@ -6,7 +6,7 @@ using BizHawk.Emulation.Common;
 
 namespace BizHawk.Emulation.Cores.Sega.MasterSystem
 {
-	public sealed partial class SMS : IDebuggable
+	public partial class SMS : IDebuggable
 	{
 		public IDictionary<string, RegisterValue> GetCpuFlagsAndRegisters()
 		{
diff --git a/BizHawk.Emulation.Cores/Consoles/Sega/SMS/SMS.IEmulator.cs b/BizHawk.Emulation.Cores/Consoles/Sega/SMS/SMS.IEmulator.cs
index f674f21797..568c55fea7 100644
--- a/BizHawk.Emulation.Cores/Consoles/Sega/SMS/SMS.IEmulator.cs
+++ b/BizHawk.Emulation.Cores/Consoles/Sega/SMS/SMS.IEmulator.cs
@@ -2,7 +2,7 @@
 
 namespace BizHawk.Emulation.Cores.Sega.MasterSystem
 {
-	public sealed partial class SMS : IEmulator
+	public partial class SMS : IEmulator
 	{
 		public IEmulatorServiceProvider ServiceProvider { get; }
 
@@ -97,15 +97,6 @@ namespace BizHawk.Emulation.Cores.Sega.MasterSystem
 			_frame++;
 			PSG.BeginFrame(Cpu.TotalExecutedCycles);
 
-			if (Tracer.Enabled)
-			{
-				Cpu.TraceCallback = s => Tracer.Put(s);
-			}
-			else
-			{
-				Cpu.TraceCallback = null;
-			}
-
 			if (!IsGameGear && IsGameGear_C)
 			{
 				Cpu.NonMaskableInterrupt = start_pressed;
diff --git a/BizHawk.Emulation.Cores/Consoles/Sega/SMS/SMS.IInputPollable.cs b/BizHawk.Emulation.Cores/Consoles/Sega/SMS/SMS.IInputPollable.cs
index ea20c139f0..c5568fa7ea 100644
--- a/BizHawk.Emulation.Cores/Consoles/Sega/SMS/SMS.IInputPollable.cs
+++ b/BizHawk.Emulation.Cores/Consoles/Sega/SMS/SMS.IInputPollable.cs
@@ -2,7 +2,7 @@
 
 namespace BizHawk.Emulation.Cores.Sega.MasterSystem
 {
-	public sealed partial class SMS : IInputPollable
+	public partial class SMS : IInputPollable
 	{
 		public int LagCount
 		{
diff --git a/BizHawk.Emulation.Cores/Consoles/Sega/SMS/SMS.IMemoryDomains.cs b/BizHawk.Emulation.Cores/Consoles/Sega/SMS/SMS.IMemoryDomains.cs
index a19dadae35..ee52785580 100644
--- a/BizHawk.Emulation.Cores/Consoles/Sega/SMS/SMS.IMemoryDomains.cs
+++ b/BizHawk.Emulation.Cores/Consoles/Sega/SMS/SMS.IMemoryDomains.cs
@@ -6,7 +6,7 @@ using BizHawk.Emulation.Common;
 
 namespace BizHawk.Emulation.Cores.Sega.MasterSystem
 {
-	public sealed partial class SMS
+	public partial class SMS
 	{
 		private MemoryDomainList MemoryDomains;
 		private readonly Dictionary<string, MemoryDomainByteArray> _byteArrayDomains = new Dictionary<string, MemoryDomainByteArray>();
diff --git a/BizHawk.Emulation.Cores/Consoles/Sega/SMS/SMS.ISaveRam.cs b/BizHawk.Emulation.Cores/Consoles/Sega/SMS/SMS.ISaveRam.cs
index 1b48b8ec52..be49228c80 100644
--- a/BizHawk.Emulation.Cores/Consoles/Sega/SMS/SMS.ISaveRam.cs
+++ b/BizHawk.Emulation.Cores/Consoles/Sega/SMS/SMS.ISaveRam.cs
@@ -4,7 +4,7 @@ using BizHawk.Emulation.Common;
 
 namespace BizHawk.Emulation.Cores.Sega.MasterSystem
 {
-	public sealed partial class SMS : ISaveRam
+	public partial class SMS : ISaveRam
 	{
 		public byte[] CloneSaveRam()
 		{
diff --git a/BizHawk.Emulation.Cores/Consoles/Sega/SMS/SMS.ISettable.cs b/BizHawk.Emulation.Cores/Consoles/Sega/SMS/SMS.ISettable.cs
index 4a45ac0e7a..fc24b04854 100644
--- a/BizHawk.Emulation.Cores/Consoles/Sega/SMS/SMS.ISettable.cs
+++ b/BizHawk.Emulation.Cores/Consoles/Sega/SMS/SMS.ISettable.cs
@@ -2,7 +2,7 @@
 
 namespace BizHawk.Emulation.Cores.Sega.MasterSystem
 {
-	public sealed partial class SMS : ISettable<SMS.SMSSettings, SMS.SMSSyncSettings>
+	public partial class SMS : ISettable<SMS.SMSSettings, SMS.SMSSyncSettings>
 	{
 		public SMSSettings GetSettings()
 		{
diff --git a/BizHawk.Emulation.Cores/Consoles/Sega/SMS/SMS.ISoundProvider.cs b/BizHawk.Emulation.Cores/Consoles/Sega/SMS/SMS.ISoundProvider.cs
index fd44ce7fe5..18f85bbc59 100644
--- a/BizHawk.Emulation.Cores/Consoles/Sega/SMS/SMS.ISoundProvider.cs
+++ b/BizHawk.Emulation.Cores/Consoles/Sega/SMS/SMS.ISoundProvider.cs
@@ -3,7 +3,7 @@
 namespace BizHawk.Emulation.Cores.Sega.MasterSystem
 {
 	// Sound refactor TODO: Implement ISoundProvider without the need for FakeSyncSound
-	public sealed partial class SMS
+	public partial class SMS
 	{
 		private FakeSyncSound _fakeSyncSound;
 		private IAsyncSoundProvider ActiveSoundProvider;
diff --git a/BizHawk.Emulation.Cores/Consoles/Sega/SMS/SMS.IStatable.cs b/BizHawk.Emulation.Cores/Consoles/Sega/SMS/SMS.IStatable.cs
index 556c158b14..2583bd8369 100644
--- a/BizHawk.Emulation.Cores/Consoles/Sega/SMS/SMS.IStatable.cs
+++ b/BizHawk.Emulation.Cores/Consoles/Sega/SMS/SMS.IStatable.cs
@@ -6,7 +6,7 @@ using BizHawk.Emulation.Common;
 
 namespace BizHawk.Emulation.Cores.Sega.MasterSystem
 {
-	public sealed partial class SMS : IStatable
+	public partial class SMS : IStatable
 	{
 		public bool BinarySaveStatesPreferred
 		{
diff --git a/BizHawk.Emulation.Cores/Consoles/Sega/SMS/SMS.cs b/BizHawk.Emulation.Cores/Consoles/Sega/SMS/SMS.cs
index 16fab92448..b320887d91 100644
--- a/BizHawk.Emulation.Cores/Consoles/Sega/SMS/SMS.cs
+++ b/BizHawk.Emulation.Cores/Consoles/Sega/SMS/SMS.cs
@@ -23,7 +23,7 @@ namespace BizHawk.Emulation.Cores.Sega.MasterSystem
 		isPorted: false,
 		isReleased: true)]
 	[ServiceNotApplicable(typeof(IDriveLight))]
-	public sealed partial class SMS : IEmulator, ISaveRam, IStatable, IInputPollable, IRegionable,
+	public partial class SMS : IEmulator, ISaveRam, IStatable, IInputPollable, IRegionable,
 		IDebuggable, ISettable<SMS.SMSSettings, SMS.SMSSyncSettings>, ICodeDataLogger
 	{
 		[CoreConstructor("SMS", "SG", "GG")]
@@ -262,7 +262,7 @@ namespace BizHawk.Emulation.Cores.Sega.MasterSystem
 
 		public DisplayType Region { get; set; }
 
-		private ITraceable Tracer { get; set; }
+		private readonly ITraceable Tracer;
 
 		string DetermineRegion(string gameRegion)
 		{
diff --git a/BizHawk.Emulation.Cores/Consoles/Sega/SMS/VDP.cs b/BizHawk.Emulation.Cores/Consoles/Sega/SMS/VDP.cs
index 1682034a9e..2d72e9fccf 100644
--- a/BizHawk.Emulation.Cores/Consoles/Sega/SMS/VDP.cs
+++ b/BizHawk.Emulation.Cores/Consoles/Sega/SMS/VDP.cs
@@ -12,7 +12,7 @@ namespace BizHawk.Emulation.Cores.Sega.MasterSystem
 	public enum VdpMode { SMS, GameGear }
 
 	// Emulates the Texas Instruments TMS9918 VDP.
-	public sealed partial class VDP : IVideoProvider
+	public partial class VDP : IVideoProvider
 	{
 		// VDP State
 		public byte[] VRAM = new byte[0x4000]; //16kb video RAM