Fixed the noise channel. Fixed speech in IM. Added 0xED57 to play WBIII

Core/Audio/SmsApu.cs

@@ -22,7 +22,9 @@ namespace Core.Audio
         private int[] _counters = new int[4];
         private int[] _polarities = new int[4] { 1, 1, 1, 1 }; // 1 = High, -1 = Low
         private ushort _lfsr = 0x8000; // Linear Feedback Shift Register (For Noise)
-        private bool _noiseFlipFlop = false;
+        // --- FILTER VARIABLES ---
+        private float _previousSample = 0f;
+        private float _previousFiltered = 0f;
 
         // The SN76489 Volume Table reduces amplitude by exactly 2 decibels per step.
         private static readonly float[] VolumeTable = {
@@ -84,39 +86,34 @@ namespace Core.Audio
             _counters[3]--;
             if (_counters[3] <= 0)
             {
-                // Reload the counter
+                // 1. Reload the counter
                 int shiftRate = Registers[6] & 0x03;
                 if (shiftRate == 0) _counters[3] = 0x10;      // Fast
                 else if (shiftRate == 1) _counters[3] = 0x20; // Medium
                 else if (shiftRate == 2) _counters[3] = 0x40; // Slow
                 else _counters[3] = (Registers[4] == 0) ? 1024 : Registers[4]; // Linked to Tone 2
 
-                // THE FIX: Toggle the internal clock (Divide by 2!)
+                // 2. NO FLIP FLOP! Shift the LFSR immediately!
-                _noiseFlipFlop = !_noiseFlipFlop;
-
-                // Only shift the random static when the clock goes High
-                if (_noiseFlipFlop)
-                {
-                    int tappedBit = _lfsr & 1;
-                    _lfsr >>= 1;
-
-                    if (tappedBit == 1)
-                    {
                 bool isWhiteNoise = (Registers[6] & 0x04) != 0;
-                        if (isWhiteNoise) _lfsr ^= 0x0009; // SMS-specific XOR mask
                 
-                        _lfsr |= 0x8000; // Inject the high bit
+                // Read the bits BEFORE shifting
-                    }
+                int bit0 = _lfsr & 1;
+                int bit3 = (_lfsr >> 3) & 1;
                 
-                    // The noise channel output is driven directly by the tapped bit
+                // The Master System physically XORs bit 0 and bit 3 for White Noise.
-                    _polarities[3] = (tappedBit == 1) ? 1 : -1;
+                // For Periodic Noise, it just feeds bit 0 straight back in.
-                }
+                int feedback = isWhiteNoise ? (bit0 ^ bit3) : bit0;
+                
+                // Shift the register right and push the feedback into the highest bit (Bit 15)
+                _lfsr = (ushort)((_lfsr >> 1) | (feedback << 15));
+
+                // The noise speaker is driven directly by the lowest bit
+                _polarities[3] = (_lfsr & 1) == 1 ? 1 : -1;
             }
         }
 
         private void MixAndOutputSample()
         {
-            // If the UI hasn't hooked up the speakers yet, just throw the audio away!
             if (AudioDevice == null) return;
 
             float sample = 0f;
@@ -124,9 +121,16 @@ namespace Core.Audio
             // Mix Tone Channels 0, 1, 2
             for (int i = 0; i < 3; i++)
             {
-                // HARDWARE QUIRK: If the tone frequency is 1 or 0, the channel outputs a 
+                int tone = Registers[i * 2];
-                // constant DC voltage instead of vibrating, meaning it is effectively silent.
+
-                if (Registers[i * 2] > 1)
+                // THE FIX 1: Catch ALL ultrasonic frequencies (1 through 5) to stop Aliasing!
+                if (tone >= 0 && tone <= 5)
+                {
+                    // THE FIX 2: Scale it by 0.5f. A fast square wave spends 50% of its time 
+                    // high, so it naturally averages out to half volume. This prevents clipping!
+                    sample += 0.5f * VolumeTable[Registers[(i * 2) + 1]];
+                }
+                else
                 {
                     sample += _polarities[i] * VolumeTable[Registers[(i * 2) + 1]];
                 }
@@ -135,10 +139,18 @@ namespace Core.Audio
             // Mix Noise Channel 3
             sample += _polarities[3] * VolumeTable[Registers[7]];
 
-            // Divide by 4 so all 4 channels together never exceed 1.0f (which would cause horrible distortion!)
+            // Divide by 4 so all 4 channels together never exceed 1.0f
             sample /= 4.0f;
 
-            AudioDevice.AddSample(sample);
+            // THE FIX 3: The DC Blocker (1-Pole High-Pass Filter)
+            // PCM speech creates a massive DC offset (pushes the speaker cone forward and leaves it there).
+            // This filter smoothly pulls the speaker cone back to center at 35Hz, removing the hum and distortion!
+            float filteredSample = sample - _previousSample + 0.995f * _previousFiltered;
+
+            _previousSample = sample;
+            _previousFiltered = filteredSample;
+
+            AudioDevice.AddSample(filteredSample);
         }
         public void WritePort7F(byte value)
         {

Core/Cpu/Z80.cs

@@ -1340,6 +1340,18 @@ namespace Core.Cpu
                 case 0x56: // IM 1
                     InterruptMode = 1;
                     return 8;
+                case 0x57: // LD A, I
+                    {
+                        AF.High = I; // Copy I into A
+                        byte flags57 = (byte)(AF.Low & 0x01); // Preserve Carry
+
+                        if ((AF.High & 0x80) != 0) flags57 |= 0x80; // S flag
+                        if (AF.High == 0) flags57 |= 0x40;          // Z flag
+                        if (IFF2) flags57 |= 0x04;                  // P/V flag gets IFF2
+                        flags57 |= (byte)(AF.High & 0x28);
+                        AF.Low = flags57;
+                        return 9;
+                    }
                 case 0x58: // IN E, (C)
                     byte inVal58 = ReadPort(BC.Word);
                     DE.Low = inVal58;

Core/SmsMachine.cs

@@ -19,7 +19,8 @@ namespace Core
         public ushort? Breakpoint { get; set; } = null;
 
         // NTSC SMS T-States per frame
-        public const int TStatesPerFrame = 59736;
+        public const int TStatesPerFrame = 59736; //NTSC
+        //public const int TStatesPerFrame = 49780; //PAL
 
         public SmsMachine()
         {
@@ -46,7 +47,7 @@ namespace Core
         public void RunFrame()
         {
             int tStatesThisFrame = 0;
-            while (tStatesThisFrame < 59736) // Standard NTSC frame time
+            while (tStatesThisFrame < TStatesPerFrame) // Standard NTSC frame time
             {
                 // 1. Run one CPU instruction
                 int cycles = Cpu.Step();

Desktop/Desktop.csproj

@@ -4,8 +4,15 @@
 		<OutputType>WinExe</OutputType>
 		<TargetFramework>net8.0-windows</TargetFramework>
 		<Nullable>enable</Nullable>
-    <UseWindowsForms>true</UseWindowsForms>
 		<ImplicitUsings>enable</ImplicitUsings>
+
+		<!-- This specific line is what maps Label, Button, TextBox, and STAThread -->
+		<UseWindowsForms>true</UseWindowsForms>
+
+		<!-- Single File Settings -->
+		<PublishSingleFile>true</PublishSingleFile>
+		<IncludeNativeLibrariesForSelfExtract>true</IncludeNativeLibrariesForSelfExtract>
+		<RuntimeIdentifier>win-x64</RuntimeIdentifier>
 	</PropertyGroup>
 
 	<ItemGroup>
@@ -352,5 +359,4 @@
 	<ItemGroup>
 		<ProjectReference Include="..\Core\Core.csproj" />
 	</ItemGroup>
-
 </Project>

Desktop/Form1.cs

@@ -18,7 +18,8 @@ namespace Desktop
         private Bitmap _screenBitmap = new Bitmap(256, 192, PixelFormat.Format32bppArgb);
         private NAudioPlayer _audioPlayer;
         private Task _emulatorTask;
-        private double TargetFrameTime = 16.667f;
+        private double TargetFrameTime = 16.667f; //NTSC
+        //private double TargetFrameTime = 20; //PAL
         public int TotalFrameCount = 0;
         public double FrameTime { get; private set; } = 0;
         public double FramesPerSecond { get; private set; } = 0;
@@ -152,7 +153,6 @@ namespace Desktop
                         }
                     }
 
-                    // --- METRICS MATH ---
                     double currentTime = _stopwatch.Elapsed.TotalMilliseconds;
                     TotalFrameCount++;
                     framesThisSecond++;
@@ -165,7 +165,7 @@ namespace Desktop
 
                         BeginInvoke((System.Windows.Forms.MethodInvoker)delegate
                         {
-                            this.Text = $"Parsons Master System - {_currentRomName} [FPS/FT: {FramesPerSecond:F0}/{FrameTime:F1}]";
+                            this.Text = $"Parsons Master System 2026 - {_currentRomName} [FPS/FT: {FramesPerSecond:F0}/{FrameTime:F1}]";
                         });
                     }