diff --git a/clean.sh b/clean.sh
index e25b8031..ae12a585 100755
--- a/clean.sh
+++ b/clean.sh
@@ -1 +1,9 @@
 rm *.zip
+rm -rf src/Zen.Common/bin
+rm -rf src/Zen.System/bin
+rm -rf src/Zen.Z80/bin
+rm -rf src/Zen.Z80.Tests/bin
+rm -rf src/Zen.Desktop.Host/bin
+rm -rf src/Zen.Utilities/bin
+rm -rf src/Zen.Z80.Test.JSMoo/bin
+rm -rf src/Zen.Z80.Tests.Fuse/bin
diff --git a/src/Zen.Desktop.Host/Infrastructure/Host.cs b/src/Zen.Desktop.Host/Infrastructure/Host.cs
index b2616199..e9325d21 100644
--- a/src/Zen.Desktop.Host/Infrastructure/Host.cs
+++ b/src/Zen.Desktop.Host/Infrastructure/Host.cs
@@ -22,8 +22,6 @@ namespace Zen.Desktop.Host.Infrastructure;
 
 public class Host : Game
 {
-    private const int StartPause = 30;
-
     // ReSharper disable once PrivateFieldCanBeConvertedToLocalVariable
     private readonly GraphicsDeviceManager _graphicsDeviceManager;
 
@@ -41,8 +39,6 @@ public class Host : Game
 
     private MenuSystem _menuSystem;
 
-    private int? _pause = StartPause;
-
     private bool _soundState;
 
     private WaveVisualiser _waveVisualiser;
@@ -122,6 +118,14 @@ private void SetMotherboard(Model model)
         _motherboard.Fast = AppSettings.Instance.Speed == Speed.Fast;
         _motherboard.Slow = AppSettings.Instance.Speed == Speed.Slow;
 
+        if (AppSettings.Instance.Speed == Speed.Locked)
+        {
+            _motherboard.Worker.Locked = true;
+            _motherboard.AyAudio.Locked = true;
+            
+            TargetElapsedTime = TimeSpan.FromMilliseconds(20);
+        }
+
         _imageName = $"Standard {model} ROM";
 
         AppSettings.Instance.SystemModel = model;
@@ -152,8 +156,6 @@ protected override void OnActivated(object sender, EventArgs args)
         {
             _motherboard.Start();
 
-            _motherboard.Pause();
-
             _hostStarted = true;
 
             _motherboard.Fast = AppSettings.Instance.Speed == Speed.Fast;
@@ -216,16 +218,9 @@ private void ScanComplete()
 
     protected override void Update(GameTime gameTime)
     {
-        if (_pause != null)
+        if (AppSettings.Instance.Speed == Speed.Locked)
         {
-            _pause--;
-        }
-
-        if (_pause == 0)
-        {
-            _pause = null;
-
-            _motherboard.Resume();
+            _motherboard.Worker.RunFrame();
         }
 
         if (Keyboard.GetState().IsKeyDown(Keys.Tab) && _menuSystem == null)
@@ -261,7 +256,6 @@ private void MenuFinished(MenuResult result, object arguments)
                 SetMotherboard((Model) arguments);
                 _motherboard.Fast = false;
                 _motherboard.Slow = false;
-                _motherboard.AyAudio.BufferSize = System.Modules.Audio.Constants.DefaultBufferSize;
                 AppSettings.Instance.Speed = Speed.Normal;
 
                 _motherboard.Start();
@@ -278,35 +272,40 @@ private void MenuFinished(MenuResult result, object arguments)
             case MenuResult.SpeedNormal:
                 _motherboard.Fast = false;
                 _motherboard.Slow = false;
-                _motherboard.AyAudio.BufferSize = System.Modules.Audio.Constants.DefaultBufferSize;
+                _motherboard.Worker.Locked = false;
+                _motherboard.AyAudio.Locked = false;
+
+                TargetElapsedTime = TimeSpan.FromTicks(166667L);
+
+                break;
+
+            case MenuResult.SpeedLocked:
+                _motherboard.Fast = false;
+                _motherboard.Slow = false;
+                _motherboard.Worker.Locked = true;
+                _motherboard.AyAudio.Locked = true;
+                
+                TargetElapsedTime = TimeSpan.FromMilliseconds(20);
 
                 break;
 
             case MenuResult.SpeedFast:
                 _motherboard.Fast = true;
                 _motherboard.Slow = false;
-                _motherboard.AyAudio.BufferSize = System.Modules.Audio.Constants.DefaultBufferSize;
+                _motherboard.Worker.Locked = false;
+                _motherboard.AyAudio.Locked = false;
+
+                TargetElapsedTime = TimeSpan.FromTicks(166667L);
 
                 break;
             
             case MenuResult.SpeedSlow:
                 _motherboard.Fast = false;
                 _motherboard.Slow = true;
-                _motherboard.AyAudio.BufferSize = System.Modules.Audio.Constants.DefaultBufferSize;
-                
-                break;
-            
-            case MenuResult.SpeedHalf:
-                _motherboard.Fast = false;
-                _motherboard.Slow = false;
-                _motherboard.AyAudio.BufferSize = System.Modules.Audio.Constants.DefaultBufferSize * 2;
-                
-                break;
-            
-            case MenuResult.SpeedQuarter:
-                _motherboard.Fast = false;
-                _motherboard.Slow = false;
-                _motherboard.AyAudio.BufferSize = System.Modules.Audio.Constants.DefaultBufferSize * 4;
+                _motherboard.Worker.Locked = false;
+                _motherboard.AyAudio.Locked = false;
+
+                TargetElapsedTime = TimeSpan.FromTicks(166667L);
 
                 break;
 
diff --git a/src/Zen.Desktop.Host/Infrastructure/Menu/MenuResult.cs b/src/Zen.Desktop.Host/Infrastructure/Menu/MenuResult.cs
index a71e4ec5..121c2495 100644
--- a/src/Zen.Desktop.Host/Infrastructure/Menu/MenuResult.cs
+++ b/src/Zen.Desktop.Host/Infrastructure/Menu/MenuResult.cs
@@ -10,8 +10,7 @@ public enum MenuResult
     SpeedNormal,
     SpeedFast,
     SpeedSlow,
-    SpeedQuarter,
-    SpeedHalf,
+    SpeedLocked,
     SaveState,
     LoadState,
     ChangeScale,
diff --git a/src/Zen.Desktop.Host/Infrastructure/Menu/SpeedMenu.cs b/src/Zen.Desktop.Host/Infrastructure/Menu/SpeedMenu.cs
index 2dd8a581..cd6e8c9f 100644
--- a/src/Zen.Desktop.Host/Infrastructure/Menu/SpeedMenu.cs
+++ b/src/Zen.Desktop.Host/Infrastructure/Menu/SpeedMenu.cs
@@ -13,13 +13,13 @@ public override List<Label> GetMenu()
                     {
                         new(0, true, "Zen - Emulator Speed", Color.White, 0, 0, null),
                         new(1, false, $"[1] {(AppSettings.Instance.Speed == Speed.Slow ? ">" : " ")} Scanline {(AppSettings.Instance.Speed == Speed.Slow ? "<" : " ")}", Color.Yellow, 1, 3, Keys.D1, Color.LightGreen),
-                        new(2, false, $"[2] {(AppSettings.Instance.Speed == Speed.Quarter ? ">" : " ")} Quarter {(AppSettings.Instance.Speed == Speed.Quarter ? "<" : " ")}", Color.Yellow, 1, 5, Keys.D2, Color.LightGreen),
-                        new(3, false, $"[3] {(AppSettings.Instance.Speed == Speed.Half ? ">" : " ")} Half {(AppSettings.Instance.Speed == Speed.Half ? "<" : " ")}", Color.Yellow, 1, 7, Keys.D3, Color.LightGreen),
-                        new(4, false, $"[4] {(AppSettings.Instance.Speed == Speed.Normal ? ">" : " ")} Normal {(AppSettings.Instance.Speed == Speed.Normal ? "<" : " ")}", Color.Yellow, 1, 9, Keys.D4, Color.LightGreen),
-                        new(5, false, $"[5] {(AppSettings.Instance.Speed == Speed.Fast ? ">" : " ")} As Fast As Possible {(AppSettings.Instance.Speed == Speed.Fast ? "<" : " ")}", Color.Yellow, 1, 11, Keys.D5, Color.LightGreen),
+                        new(2, false, $"[2] {(AppSettings.Instance.Speed == Speed.Locked ? ">" : " ")} Locked 50Hz {(AppSettings.Instance.Speed == Speed.Locked ? "<" : " ")}", Color.Yellow, 1, 5, Keys.D2, Color.LightGreen),
+                        new(3, false, $"[3] {(AppSettings.Instance.Speed == Speed.Normal ? ">" : " ")} Normal {(AppSettings.Instance.Speed == Speed.Normal ? "<" : " ")}", Color.Yellow, 1, 7, Keys.D3, Color.LightGreen),
+                        new(4, false, $"[4] {(AppSettings.Instance.Speed == Speed.Fast ? ">" : " ")} As Fast As Possible {(AppSettings.Instance.Speed == Speed.Fast ? "<" : " ")}", Color.Yellow, 1, 9, Keys.D4, Color.LightGreen),
                         new(96, true, "This setting is not saved", Color.Wheat, 0, 15, null),
                         new(97, true, "Zen always starts", Color.Wheat, 0, 17, null),
-                        new(98, true, "at Normal speed", Color.Wheat, 0, 18, null),
+                        new(98, true, "at Normal speed or", Color.Wheat, 0, 18, null),
+                        new(98, true, "Locked 50Hz on Linux", Color.Wheat, 0, 19, null),
                         new(99, true, "[ESC] Close Menu", Color.FromNonPremultiplied(255, 64, 64, 255), 0, 21, Keys.Escape, Color.LightGreen)
                     };
 
@@ -36,21 +36,16 @@ public override (MenuResult Result, MenuBase NewMenu, object Arguments) ItemSele
                 return (MenuResult.SpeedSlow, null, null);
 
             case 2:
-                AppSettings.Instance.Speed = Speed.Quarter;
+                AppSettings.Instance.Speed = Speed.Locked;
 
-                return (MenuResult.SpeedQuarter, null, null);
+                return (MenuResult.SpeedLocked, null, null);
 
             case 3:
-                AppSettings.Instance.Speed = Speed.Half;
-
-                return (MenuResult.SpeedHalf, null, null);
-
-            case 4:
                 AppSettings.Instance.Speed = Speed.Normal;
 
                 return (MenuResult.SpeedNormal, null, null);
 
-            case 5:
+            case 4:
                 AppSettings.Instance.Speed = Speed.Fast;
 
                 return (MenuResult.SpeedFast, null, null);
diff --git a/src/Zen.Desktop.Host/Infrastructure/Settings/AppSettings.cs b/src/Zen.Desktop.Host/Infrastructure/Settings/AppSettings.cs
index 71cdc6f9..e88f1d0b 100644
--- a/src/Zen.Desktop.Host/Infrastructure/Settings/AppSettings.cs
+++ b/src/Zen.Desktop.Host/Infrastructure/Settings/AppSettings.cs
@@ -60,7 +60,9 @@ private static AppSettings GetAppSettings()
             Logger.LogException(nameof(AppSettings), exception);
         }
 
-        settings.Speed = Speed.Normal;
+        settings.Speed = RuntimeInformation.IsOSPlatform(OSPlatform.Linux)
+            ? Speed.Locked
+            : Speed.Normal;
 
         return settings;
     }
diff --git a/src/Zen.Desktop.Host/Infrastructure/Settings/Speed.cs b/src/Zen.Desktop.Host/Infrastructure/Settings/Speed.cs
index c7dec170..fa4f27cd 100644
--- a/src/Zen.Desktop.Host/Infrastructure/Settings/Speed.cs
+++ b/src/Zen.Desktop.Host/Infrastructure/Settings/Speed.cs
@@ -3,8 +3,7 @@ namespace Zen.Desktop.Host.Infrastructure.Settings;
 public enum Speed
 {
     Slow,
-    Quarter,
-    Half,
+    Locked,
     Normal,
     Fast
 }
\ No newline at end of file
diff --git a/src/Zen.System/Modules/AyAudio.cs b/src/Zen.System/Modules/AyAudio.cs
index 9436fb50..26efbc62 100644
--- a/src/Zen.System/Modules/AyAudio.cs
+++ b/src/Zen.System/Modules/AyAudio.cs
@@ -32,7 +32,7 @@ public class AyAudio : IDisposable
 
     private byte _registerNumber;
 
-    private float[] _buffer;
+    private readonly float[] _buffer;
 
     private int _readQueue;
 
@@ -42,18 +42,6 @@ public class AyAudio : IDisposable
 
     private ManualResetEvent? _workerResetEvent;
 
-    private int _bufferSize = Constants.DefaultBufferSize;
-
-    public int BufferSize
-    {
-        set
-        {
-            _bufferSize = value;
-
-            _buffer = new float[_bufferSize];
-        }
-    }
-
     public IZenAudioEngine AudioEngine
     {
         set
@@ -65,6 +53,8 @@ public IZenAudioEngine AudioEngine
         get => _engine;
     }
 
+    public bool Locked { get; set; }
+    
     public bool Silent { get; set; }
 
     public Action<float[]>? AySignalHook { get; set; }
@@ -75,7 +65,7 @@ public AyAudio(IZenAudioEngine engine)
     {
         _engine = engine;
         
-        _buffer = new float[_bufferSize];
+        _buffer = new float[Constants.DefaultBufferSize];
 
         _cancellationTokenSource = new CancellationTokenSource();
 
@@ -90,7 +80,13 @@ public AyAudio(IZenAudioEngine engine)
 
     public void Start()
     {
-        _audioThread = Task.Run(RunFrame, _cancellationToken);
+        _audioThread = Task.Run(() =>
+        {
+            if (! Locked)
+            {
+                RunFrame();
+            }
+        }, _cancellationToken);
     }
 
     public void FrameReady(ManualResetEvent resetEvent)
@@ -283,7 +279,7 @@ private void RunFrame()
     {
         var signals = new float[3];
 
-        var bufferStep = (float) Common.Constants.FrameCycles / (_bufferSize - 1);
+        var bufferStep = (float) Common.Constants.FrameCycles / (Constants.DefaultBufferSize - 1);
 
         while (! _cancellationToken.IsCancellationRequested)
         {
@@ -293,7 +289,7 @@ private void RunFrame()
 
                 _resetEvent.Reset();
 
-                for (var i = 0; i < _bufferSize; i++)
+                for (var i = 0; i < Constants.DefaultBufferSize; i++)
                 {
                     if (Silent)
                     {
diff --git a/src/Zen.System/Modules/Ram.cs b/src/Zen.System/Modules/Ram.cs
index 6d8e6164..50bf3b51 100644
--- a/src/Zen.System/Modules/Ram.cs
+++ b/src/Zen.System/Modules/Ram.cs
@@ -18,12 +18,11 @@ public class Ram
 
     private byte _screenBank = 5;
 
-    public bool ProtectRom { get; set; }
+    public bool ProtectRom { get; init; }
 
     public byte ScreenBank
     {
         set => _screenBank = (byte) (value == 1 ? 5 : 7);
-        get => _screenBank;
     }
 
     public byte[] WorkingScreenRam => _banks[_screenBank];
diff --git a/src/Zen.System/Modules/Worker.cs b/src/Zen.System/Modules/Worker.cs
index 5d5696e5..417edfb2 100644
--- a/src/Zen.System/Modules/Worker.cs
+++ b/src/Zen.System/Modules/Worker.cs
@@ -41,6 +41,8 @@ public class Worker : IDisposable
     public bool Fast { get; set; }
     
     public bool Slow { get; set; }
+    
+    public bool Locked { get; set; }
 
     public Worker(Interface @interface, VideoModulator videoModulator, AyAudio ayAudio)
     {
@@ -109,84 +111,92 @@ private void TimerWorker()
     {
         while (! _cancellationToken.IsCancellationRequested)
         {
-            try
+            if (! Locked)
             {
-                if (! _paused)
-                {
-                    _frameCycles = 0;
+                RunFrame();
+            }
+        }
+        // ReSharper disable once FunctionNeverReturns
+    }
+
+    public void RunFrame()
+    {
+        try
+        {
+            if (! _paused)
+            {
+                _frameCycles = 0;
 
-                    _videoModulator.StartFrame();
+                _videoModulator.StartFrame();
 
-                    while (_frameCycles < Constants.FrameCycles)
+                while (_frameCycles < Constants.FrameCycles)
+                {
+                    if (_frameCycles is >= Constants.InterruptStart and < Constants.InterruptEnd)
                     {
-                        if (_frameCycles is >= Constants.InterruptStart and < Constants.InterruptEnd)
-                        {
-                            _interface.INT = true;
+                        _interface.INT = true;
 
-                            _scanStates = 0;
+                        _scanStates = 0;
 
-                            _lastScanComplete = 0;
-                        }
-                        else
-                        {
-                            _interface.INT = false;
-                        }
+                        _lastScanComplete = 0;
+                    }
+                    else
+                    {
+                        _interface.INT = false;
+                    }
 
-                        ClearFrameRamBuffer();
+                    ClearFrameRamBuffer();
 
-                        var cycles = OnTick(_frameCycles);
+                    var cycles = OnTick(_frameCycles);
 
-                        var instructionCycles = 0;
-                        
-                        for (var i = 0; i < 7; i++)
-                        {
-                            if (i > 0 && cycles[i] == 0)
-                            {
-                                break;
-                            }
+                    var instructionCycles = 0;
 
-                            _frameCycles += cycles[i];
-
-                            instructionCycles += cycles[i];
+                    for (var i = 0; i < 7; i++)
+                    {
+                        if (i > 0 && cycles[i] == 0)
+                        {
+                            break;
+                        }
 
-                            _frameCycles += ApplyFrameRamChanges(i, _frameCycles, cycles);
+                        _frameCycles += cycles[i];
 
-                            if (cycles[i] > 0)
-                            {
-                                _videoModulator.CycleComplete(_frameCycles);
-                            }
-                        }
+                        instructionCycles += cycles[i];
 
-                        _scanStates += instructionCycles;
+                        _frameCycles += ApplyFrameRamChanges(i, _frameCycles, cycles);
 
-                        if (Slow && _scanStates - _lastScanComplete > Constants.StatesPerScreenLine * Constants.SlowScanFactor)
+                        if (cycles[i] > 0)
                         {
-                            _scanResetEvent.WaitOne();
-
-                            _lastScanComplete = _scanStates;
+                            _videoModulator.CycleComplete(_frameCycles);
                         }
                     }
 
-                    if (! Fast)
+                    _scanStates += instructionCycles;
+
+                    if (Slow && _scanStates - _lastScanComplete > Constants.StatesPerScreenLine * Constants.SlowScanFactor)
                     {
-                        _resetEvent.WaitOne();
-                    }
+                        _scanResetEvent.WaitOne();
 
-                    Counters.Instance.IncrementCounter(Counter.SpectrumFrames);
+                        _lastScanComplete = _scanStates;
+                    }
                 }
 
-                _ayAudio.FrameReady(_resetEvent);
+                if (! Fast && ! Locked)
+                {
+                    _resetEvent.WaitOne();
+                }
 
-                _resetEvent.Reset();
+                Counters.Instance.IncrementCounter(Counter.SpectrumFrames);
             }
-            catch (Exception exception)
-            {
-                Logger.LogException(nameof(Worker), exception);
 
-                throw;
-            }
+            _ayAudio.FrameReady(_resetEvent);
+
+            _resetEvent.Reset();
+        }
+        catch (Exception exception)
+        {
+            Logger.LogException(nameof(Worker), exception);
+
+            throw;
         }
-        // ReSharper disable once FunctionNeverReturns
     }
 
     private void ClearFrameRamBuffer()
diff --git a/src/Zen.System/Motherboard.cs b/src/Zen.System/Motherboard.cs
index a8a7f396..f8cd8870 100644
--- a/src/Zen.System/Motherboard.cs
+++ b/src/Zen.System/Motherboard.cs
@@ -68,6 +68,8 @@ public bool Slow
     {
         set => _worker.Slow = value;
     }
+    
+    public Worker Worker => _worker;
 
     public bool Sound
     {
diff --git a/src/Zen.sln b/src/Zen.sln
index 0d0f3923..ec32f322 100644
--- a/src/Zen.sln
+++ b/src/Zen.sln
@@ -50,6 +50,7 @@ Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "Scripts", "Scripts", "{9302
 		..\test-fuse.sh = ..\test-fuse.sh
 		..\test-jsmoo.sh = ..\test-jsmoo.sh
 		..\publish-app.sh = ..\publish-app.sh
+		..\clean.sh = ..\clean.sh
 	EndProjectSection
 EndProject
 Global