First OS Agnostic Commit

Core/Audio/SmsApu.cs

@@ -33,7 +33,9 @@ namespace Core.Audio
             0.1584f, 0.1258f, 0.1000f, 0.0794f, 0.0630f, 0.0501f, 0.0398f, 0.0f
         };
 
+#pragma warning disable CS8618 // Non-nullable field must contain a non-null value when exiting constructor. Consider adding the 'required' modifier or declaring as nullable.
         public SmsApu()
+#pragma warning restore CS8618 // Non-nullable field must contain a non-null value when exiting constructor. Consider adding the 'required' modifier or declaring as nullable.
         {
             Registers[1] = 0x0F;
             Registers[3] = 0x0F;

Core/Cpu/Z80.cs

@@ -25,10 +25,13 @@ namespace Core.Cpu
 
         public int InterruptMode { get; private set; } = 0;
 
+
         // Interrupt Flip-Flops
         public bool IFF1 { get; private set; } = false;
         public bool IFF2 { get; private set; } = false;
         public bool InterruptRequested { get; private set; } = false;
+        private int _eiDelay = 0;
+        public bool IsHalted { get; private set; } = false;
 
         // Main Register Set
         public RegisterPair AF;
@@ -48,7 +51,7 @@ namespace Core.Cpu
 
         // Special Purpose Registers
         public ushort PC; // Program Counter
-        public ushort SP; // Stack Pointer
+        public ushort SP;
         public byte I;    // Interrupt Vector
         public byte R;    // Memory Refresh
 
@@ -96,6 +99,10 @@ namespace Core.Cpu
             IFF2 = false;
             InterruptMode = 0;
             TotalTStates = 0;
+
+            _eiDelay = 0;
+            IsHalted = false;
+            InterruptRequested = false;
         }
 
         public void SaveState(BinaryWriter bw)
@@ -135,6 +142,7 @@ namespace Core.Cpu
 
         public int RequestInterrupt()
         {
+            IsHalted = false;
             InterruptRequested = true;
             // 1. If the ROM has disabled interrupts (DI), ignore the request
             if (!IFF1) return 0;
@@ -143,6 +151,8 @@ namespace Core.Cpu
             IFF1 = false;
             IFF2 = false;
 
+            _eiDelay = 0;
+
             // 3. Push the current Program Counter to the stack so we can return later
             Push(PC);
 
@@ -214,14 +224,36 @@ namespace Core.Cpu
 
         public int Step()
         {
+            int tStates;
 
-            // Fetch the next opcode and increment the Program Counter
-            byte opcode = ReadMemory(PC++);
-            R = (byte)((R + 1) & 0x7F);
-            int tStates = ExecuteOpcode(opcode);
+            R = (byte)((R & 0x80) | ((R + 1) & 0x7F));
+
+            if (IsHalted)
+            {
+                // The CPU is asleep! Do not fetch instructions, just pass the time.
+                tStates = 4;
                 TotalTStates += tStates;
+            }
+            else
+            {
+                // Normal execution
+                byte opcode = ReadMemory(PC++);
+                tStates = ExecuteOpcode(opcode);
+                TotalTStates += tStates;
+            }
+
+            // The interrupt enablement perfectly mimics the physical hardware delay.
+            // This MUST tick down even if the CPU is halted!
+            if (_eiDelay > 0)
+            {
+                _eiDelay--;
+                if (_eiDelay == 0)
+                {
+                    IFF1 = true;
+                    IFF2 = true;
+                }
+            }
 
-            // Decode and execute
             return tStates;
         }
 
@@ -240,9 +272,6 @@ namespace Core.Cpu
                    $"C:{f & 1}";
         }
 
-        // =========================================================================
-        // MATH AND LOGIC HELPERS
-        // =========================================================================
 
         private void SubA(byte value, bool isCompare)
         {
@@ -925,16 +954,20 @@ namespace Core.Cpu
                 case 0x74: WriteMemory(HL.Word, HL.High); return 7;
                 case 0x75: WriteMemory(HL.Word, HL.Low); return 7;
                 case 0x76: // HALT
-                    if (!InterruptRequested)
-                    {
-                        PC--;
+                    IsHalted = true;
                     return 4;
-                    }
-                    else
-                    {
-                        InterruptRequested = false;
-                        return 4;
-                    }
+
+                //case 0x76: //HALT
+                //    if (!InterruptRequested)
+                //    {
+                //        PC--;
+                //        return 4;
+                //    }
+                //    else
+                //    {
+                //        InterruptRequested = false;
+                //        return 4;
+                //    }
                 case 0x77: WriteMemory(HL.Word, AF.High); return 7;
 
                 // --- LD A, r ---
@@ -1272,6 +1305,11 @@ namespace Core.Cpu
                 case 0xF3: // DI 
                     IFF1 = false;
                     IFF2 = false;
+                    _eiDelay = 0; // Hard cancel any pending EI delays
+                    return 4;
+
+                case 0xFB: // EI
+                    _eiDelay = 2; // Ticks down across the current and subsequent instruction
                     return 4;
                 case 0xf5: //push af
                     Push(AF.Word);
@@ -1282,10 +1320,7 @@ namespace Core.Cpu
                 case 0xF9: // LD SP, HL
                     SP = HL.Word;
                     return 6;
-                case 0xFB: // EI
-                    IFF1 = true;
-                    IFF2 = true;
-                    return 4;
+                
                 case 0xFD:
                     return ExecuteFDPrefix();
                 case 0xFE: // CP n
@@ -1303,6 +1338,35 @@ namespace Core.Cpu
 
             switch (extendedOpcode)
             {
+                case 0x40: // IN B, (C)
+                    {
+                        byte inVal40 = ReadPort(BC.Word);
+                        BC.High = inVal40;
+
+                        byte flags40 = (byte)(AF.Low & 0x01); // Preserve Carry
+                        if ((inVal40 & 0x80) != 0) flags40 |= 0x80; // S
+                        if (inVal40 == 0) flags40 |= 0x40;          // Z
+                        flags40 |= ParityTable[inVal40];            // P/V
+                        flags40 |= (byte)(inVal40 & 0x28);          // Undocumented bits 3 and 5
+
+                        AF.Low = flags40;
+                        return 12;
+                    }
+
+                case 0x50: // IN D, (C)
+                    {
+                        byte inVal50 = ReadPort(BC.Word);
+                        DE.High = inVal50;
+
+                        byte flags50 = (byte)(AF.Low & 0x01); // Preserve Carry
+                        if ((inVal50 & 0x80) != 0) flags50 |= 0x80; // S
+                        if (inVal50 == 0) flags50 |= 0x40;          // Z
+                        flags50 |= ParityTable[inVal50];            // P/V
+                        flags50 |= (byte)(inVal50 & 0x28);          // Undocumented bits 3 and 5
+
+                        AF.Low = flags50;
+                        return 12;
+                    }
                 case 0x41: // OUT (C), B
                     _simpleIoBus.WritePort(BC.Word, BC.High);
                     return 12;
@@ -1798,7 +1862,8 @@ namespace Core.Cpu
                         return 16;
                     }
                 default:
-                    throw new NotImplementedException($"Extended ED Opcode 0x{extendedOpcode:X2} at PC 0x{(PC - 1):X4} is not implemented.");
+                    return 8;
+                    //throw new NotImplementedException($"Extended ED Opcode 0x{extendedOpcode:X2} at PC 0x{(PC - 1):X4} is not implemented.");
             }
         }
 

Core/Io/SmsIoBus.cs

@@ -6,8 +6,12 @@ namespace Core.Io
 {
     public class SmsIoBus : IIoBus
     {
+#pragma warning disable CS8618 // Non-nullable field must contain a non-null value when exiting constructor. Consider adding the 'required' modifier or declaring as nullable.
         public SmsVdp VideoProcessor { get; set; }
+#pragma warning restore CS8618 // Non-nullable field must contain a non-null value when exiting constructor. Consider adding the 'required' modifier or declaring as nullable.
+#pragma warning disable CS8618 // Non-nullable field must contain a non-null value when exiting constructor. Consider adding the 'required' modifier or declaring as nullable.
         public SmsApu AudioProcessor { get; set; }
+#pragma warning restore CS8618 // Non-nullable field must contain a non-null value when exiting constructor. Consider adding the 'required' modifier or declaring as nullable.
 
         // Joypad State (0xFF means no buttons pressed - the SMS uses Active-Low logic!)
         public byte Joypad1Keyboard = 0xFF;
@@ -25,7 +29,11 @@ namespace Core.Io
                 // VDP V-Counter (Vertical Scanline Position)
                 return VideoProcessor.ReadVCounter();
             }
-
+            if (lowerPort == 0x7F)
+            {
+                // THE FIX: VDP H-Counter (Horizontal Pixel Position)
+                return VideoProcessor.ReadHCounter();
+            }
             if (lowerPort >= 0x80 && lowerPort <= 0xBF)
             {
                 // Even ports (like 0xBE) are Data. Odd ports (like 0xBF) are Control.

Core/Memory/SmsMemoryBus.cs

@@ -6,6 +6,7 @@ namespace Core.Memory
 {
     public class SmsMemoryBus : IMemory
     {
+        private bool _isCodemastersMapper = false; //Codemasters used their own memory mapper
         // SMS has 8KB of internal Work RAM
         private readonly byte[] _workRam = new byte[0x2000];
 
@@ -42,41 +43,101 @@ namespace Core.Memory
 
         public byte Read(ushort address)
         {
-            if (address < 0x4000) // ROM Slot 0 (0x0000 - 0x3FFF)
+            if (address < 0xC000 && !_isCartridgeLoaded)
             {
-                // SMS Hardware Quirk: The first 1KB (0x0000 - 0x03FF) is NEVER paged. 
-                if (address < 0x0400) return ReadFromCartridge(0, address);
+                return 0xFF;
+            }
 
-                return ReadFromCartridge(_romBank0, address);
-            }
-            if (address < 0x8000) // ROM Slot 1 (0x4000 - 0x7FFF)
+            if (address < 0x4000)
             {
-                return ReadFromCartridge(_romBank1, address & 0x3FFF);
-            }
-            if (address < 0xC000) // ROM Slot 2 (0x8000 - 0xBFFF)
+                if (!_isCodemastersMapper && address < 0x0400)
                 {
-                // --- THE MISSING LINK: Read from Save RAM if enabled! ---
+                    return _cartridgeRom[address];
+                }
+                if (address < 0x0400)
+                {
+                    return _cartridgeRom[address];
+                }
+                // Slot 0
+                return _cartridgeRom[(_romBank0 * 0x4000) + address];
+            }
+            if (address < 0x8000)
+            {
+                // Slot 1
+                return _cartridgeRom[(_romBank1 * 0x4000) + (address - 0x4000)];
+            }
+            if (address < 0xC000)
+            {
+                // Slot 2 (Or SRAM)
                 if ((_mapperControl & 0x08) != 0)
-                {
-                    int ramBank = (_mapperControl & 0x04) != 0 ? 1 : 0;
-                    int ramOffset = (ramBank * 0x4000) + (address & 0x1FFF);
-                    return _cartridgeRam[ramOffset];
+                    return _cartridgeRam[address - 0x8000];
+                else
+                    return _cartridgeRom[(_romBank2 * 0x4000) + (address - 0x8000)];
             }
 
-                // Otherwise, read from the ROM as usual
-                return ReadFromCartridge(_romBank2, address & 0x3FFF);
-            }
-
-            // System RAM (0xC000 - 0xFFFF)
+            // Bitwise AND perfectly forces 0xE000-0xFFFF to mirror down to 0xC000!
             return _workRam[address & 0x1FFF];
         }
 
+        public void Write(ushort address, byte value)
+        {
+            // Codemasters games bank-switch by writing directly to ROM!
+            if (address == 0x0000 || address == 0x4000 || address == 0x8000)
+            {
+                _isCodemastersMapper = true;
+                int cTotalBanks = _cartridgeRom.Length / 0x4000;
+                if (cTotalBanks == 0) cTotalBanks = 1;
+
+                if (address == 0x0000) _romBank0 = value % cTotalBanks;
+                else if (address == 0x4000) _romBank1 = value % cTotalBanks;
+                else if (address == 0x8000) _romBank2 = value % cTotalBanks;
+                return;
+            }
+            if (address < 0x8000) return; // Cannot write to physical ROM
+
+            if (address < 0xC000)
+            {
+                if ((_mapperControl & 0x08) != 0)
+                    _cartridgeRam[address - 0x8000] = value;
+                return;
+            }
+
+            // THE FIX 1: Save to RAM using the mirror mask
+            _workRam[address & 0x1FFF] = value;
+
+            // THE FIX 2: Mapper Control Registers live at the very end of the mirrored RAM!
+            if (address >= 0xFFFC)
+            {
+                // Calculate the absolute maximum number of banks inside the currently loaded ROM
+                int totalBanks = _cartridgeRom.Length / 0x4000;
+
+                // Safety catch for empty slots
+                if (totalBanks == 0) totalBanks = 1;
+
+                if (address == 0xFFFC)
+                {
+                    _mapperControl = value;
+                }
+                else if (address == 0xFFFD)
+                {
+                    _romBank0 = value % totalBanks; // Force the bank to stay inside the array bounds!
+                }
+                else if (address == 0xFFFE)
+                {
+                    _romBank1 = value % totalBanks;
+                }
+                else if (address == 0xFFFF)
+                {
+                    _romBank2 = value % totalBanks;
+                }
+            }
+        }
+
         //public byte Read(ushort address)
         //{
         //    if (address < 0x4000) // ROM Slot 0 (0x0000 - 0x3FFF)
         //    {
         //        // SMS Hardware Quirk: The first 1KB (0x0000 - 0x03FF) is NEVER paged. 
-        //        // It is hardwired to Bank 0 so the interrupt handlers don't crash.
         //        if (address < 0x0400) return ReadFromCartridge(0, address);
 
         //        return ReadFromCartridge(_romBank0, address);
@@ -87,102 +148,72 @@ namespace Core.Memory
         //    }
         //    if (address < 0xC000) // ROM Slot 2 (0x8000 - 0xBFFF)
         //    {
-        //        // Check if Cartridge RAM is enabled (Bit 3 of Mapper Control)
+        //        // --- THE MISSING LINK: Read from Save RAM if enabled! ---
         //        if ((_mapperControl & 0x08) != 0)
         //        {
-        //            // Bit 2 decides if we read the first 16KB half or the second 16KB half of the RAM chip
         //            int ramBank = (_mapperControl & 0x04) != 0 ? 1 : 0;
-        //            int ramOffset = (ramBank * 0x4000) + (address & 0x3FFF);
+        //            int ramOffset = (ramBank * 0x4000) + (address & 0x1FFF);
         //            return _cartridgeRam[ramOffset];
         //        }
 
+        //        // Otherwise, read from the ROM as usual
         //        return ReadFromCartridge(_romBank2, address & 0x3FFF);
         //    }
 
-        //    // If we are here, we are in System RAM (0xC000 - 0xFFFF)
-        //    // The & 0x1FFF handles the 8KB mirroring automatically!
+        //    // System RAM (0xC000 - 0xFFFF)
         //    return _workRam[address & 0x1FFF];
         //}
 
+
         //public void Write(ushort address, byte value)
         //{
-        //    // --- 1. CARTRIDGE RAM (Save Data) ---
         //    if (address < 0xC000)
         //    {
+        //        // Bypass the lock if they are trying to save their game!
         //        if (address >= 0x8000 && (_mapperControl & 0x08) != 0)
         //        {
+        //            SramUsed = true;
         //            int ramBank = (_mapperControl & 0x04) != 0 ? 1 : 0;
-        //            int ramOffset = (ramBank * 0x4000) + (address & 0x3FFF);
+        //            int ramOffset = (ramBank * 0x4000) + (address & 0x1FFF);
         //            _cartridgeRam[ramOffset] = value;
+        //            return;
         //        }
 
         //        // You cannot write to a ROM cartridge!
         //        return;
         //    }
 
-        //    // --- 2. SYSTEM RAM ---
+        //    // Write to System RAM
         //    _workRam[address & 0x1FFF] = value;
 
-        //    // --- 3. SEGA MAPPER (With Hardware Mirroring!) ---
-        //    // By checking the masked address (address & 0x1FFF), we perfectly
-        //    // catch writes to 0xFFFC-0xFFFF *and* their 0xDFFC-0xDFFF mirrors!
-        //    int mapperAddress = address & 0x1FFF;
-
-        //    if (mapperAddress == 0x1FFC) _mapperControl = value;
-        //    else if (mapperAddress == 0x1FFD) _romBank0 = value;
-        //    else if (mapperAddress == 0x1FFE) _romBank1 = value;
-        //    else if (mapperAddress == 0x1FFF) _romBank2 = value;
+        //    // --- THE SEGA MAPPER ---
+        //    if (address == 0xFFFC) // <-- ADD THIS
+        //    {
+        //        _mapperControl = value;
+        //    }
+        //    else if (address == 0xFFFD)
+        //    {
+        //        _romBank0 = value;
         //    }
 
-        public void Write(ushort address, byte value)
-        {
-            if (address < 0xC000)
-            {
-                // Bypass the lock if they are trying to save their game!
-                if (address >= 0x8000 && (_mapperControl & 0x08) != 0)
-                {
-                    SramUsed = true;
-                    int ramBank = (_mapperControl & 0x04) != 0 ? 1 : 0;
-                    int ramOffset = (ramBank * 0x4000) + (address & 0x1FFF);
-                    _cartridgeRam[ramOffset] = value;
-                    return;
-                }
+        //    // Write to System RAM
+        //    _workRam[address & 0x1FFF] = value;
 
-                // You cannot write to a ROM cartridge!
-                return;
-            }
-
-            // Write to System RAM
-            _workRam[address & 0x1FFF] = value;
-
-            // --- THE SEGA MAPPER ---
-            if (address == 0xFFFC) // <-- ADD THIS
-            {
-                _mapperControl = value;
-            }
-            else if (address == 0xFFFD)
-            {
-                _romBank0 = value;
-            }
-
-            // Write to System RAM
-            _workRam[address & 0x1FFF] = value;
-
-            // --- THE SEGA MAPPER ---
-            // If the CPU wrote to the very top of memory, it is commanding a bank swap!
-            if (address == 0xFFFD)
-            {
-                _romBank0 = value;
-            }
-            else if (address == 0xFFFE)
-            {
-                _romBank1 = value;
-            }
-            else if (address == 0xFFFF)
-            {
-                _romBank2 = value;
-            }
-        }
+        //    // --- THE SEGA MAPPER ---
+        //    // If the CPU wrote to the very top of memory, it is commanding a bank swap!
+        //    if (address == 0xFFFD)
+        //    {
+        //        _romBank0 = value;
+        //    }
+        //    else if (address == 0xFFFE)
+        //    {
+        //        _romBank1 = value;
+        //    }
+        //    else if (address == 0xFFFF)
+        //    {
+        //        _romBank2 = value;
+        //    }
+        //}
 
         private byte ReadFromCartridge(int bankIndex, int offset)
         {
@@ -252,6 +283,7 @@ namespace Core.Memory
         {
             Array.Clear(_workRam, 0, _workRam.Length);
             _mapperControl = 0;
+            _isCodemastersMapper = false;
         }
     }
 }

Core/SmsMachine.cs

@@ -17,6 +17,7 @@ namespace Core
         public SmsVdp VideoProcessor { get; private set; }
         public SmsApu AudioProcessor { get; private set; }
         public ushort? Breakpoint { get; set; } = null;
+        private int _tStateCarryover = 0;
 
         // NTSC SMS T-States per frame
         public const int TStatesPerFrame = 59736; //NTSC
@@ -40,13 +41,15 @@ namespace Core
         public void Reset()
         {
             MemoryBus.CleanRAMData();
+            VideoProcessor.Reset();
             Cpu.Reset();
+            _tStateCarryover = 0;
         }
 
 
         public void RunFrame()
         {
-            int tStatesThisFrame = 0;
+            int tStatesThisFrame = _tStateCarryover;
             while (tStatesThisFrame < TStatesPerFrame) // Standard NTSC frame time
             {
                 // 1. Run one CPU instruction
@@ -58,13 +61,17 @@ namespace Core
                 AudioProcessor.Update(cycles);
 
                 // 3. Check if the VDP is begging for attention!
-                if (VideoProcessor.InterruptPending && Cpu.IFF1)
+                //if (VideoProcessor.InterruptPending && Cpu.IFF1)
+                if (VideoProcessor.InterruptPending)
                 {
                     int intCycles = Cpu.RequestInterrupt();
+                    if (intCycles > 0)
+                    {
                         tStatesThisFrame += intCycles;
                         VideoProcessor.Update(intCycles);
                         AudioProcessor.Update(intCycles);
                     }
+                }
 
                 // 4. THE RESTORED BREAKPOINT TRAP
                 if (Breakpoint.HasValue && Cpu.PC == Breakpoint.Value)

Core/Video/SmsVdp.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Diagnostics;
 using System.IO;
 
 namespace Core.Video
@@ -7,7 +8,8 @@ namespace Core.Video
     {
         // The VDP's private memory! The CPU cannot touch these arrays directly.
         public byte[] VRAM { get; private set; } = new byte[0x4000]; // 16KB Video RAM
-        public byte[] CRAM { get; private set; } = new byte[0x20];   // 32 Bytes Color Palette
+        public byte[] smsCRAM { get; private set; } = new byte[0x20];   // Master System - 32 Bytes colour Palette
+        public byte[] ggCRAM { get; private set; } = new byte[0x40]; // GameGear - 64 Bytes colour palette
         public byte[] Registers { get; private set; } = new byte[16]; // 11 Hardware Control Registers
         public int[] FrameBuffer { get; private set; } = new int[256 * 192];
         private bool[] _priorityBuffer = new bool[256 * 192]; // Tracks priority pixels!
@@ -25,17 +27,20 @@ namespace Core.Video
         private int _currentScanline = 0;
         private int _lineCounter = 0;
         private byte _statusRegister = 0x00;
+        public bool IsGameGear { get; set; } = false;
 
         public bool InterruptPending =>
             ((_statusRegister & 0x80) != 0 && (Registers[1] & 0x20) != 0) || // VBlank
             ((_statusRegister & 0x40) != 0 && (Registers[0] & 0x10) != 0);   // Line Interrupt
 
+        
+
         public byte ReadDataPort() // Port 0xBE
         {
             _isSecondControlByte = false; // Reading data resets the control latch
             byte value = _readBuffer;
             _readBuffer = VRAM[_controlWord & 0x3FFF];
-            _controlWord++;
+            IncrementVdpAddress();
             return value;
         }
 
@@ -44,8 +49,8 @@ namespace Core.Video
             _isSecondControlByte = false;
             byte currentStatus = _statusRegister;
 
-            // CRITICAL HARDWARE QUIRK: Reading the status port physically 
-            // clears the flags inside the chip! If we don't clear this, 
+            // Reading the status port physically 
+            // clears the flags inside the chip If we don't clear this, 
             // the interrupt line gets stuck on forever.
             _statusRegister = 0x00;
 
@@ -60,15 +65,24 @@ namespace Core.Video
             int address = _controlWord & 0x3FFF;
             int command = (_controlWord >> 14) & 0x03;
 
-            if (command == 3) // Code 3: Write to Color Palette (CRAM)
+            if (command == 3) // Code 3: Write to Colour Palette (CRAM)
             {
-                CRAM[address & 0x1F] = value;
+                if (IsGameGear)
+                {
+                    ggCRAM[address & 0x3F] = value; // GG has 64 bytes of CRAM
                 }
-            else // Code 0, 1, 2: Write to VRAM
+                else
+                {
+                    smsCRAM[address & 0x1F] = value; // SMS has 32 bytes of CRAM
+                }
+            }
+            else // THE FIX: Code 0, 1, 2: Write graphics to VRAM!
             {
                 VRAM[address] = value;
             }
-            _controlWord++; // Auto-increment so the Z80 can blast data fast
+
+            // THE FIX: The pointer MUST auto-increment so the CPU can blast data fast!
+            IncrementVdpAddress();
         }
 
         public void WriteControlPort(byte value) // Port 0xBF
@@ -90,7 +104,7 @@ namespace Core.Video
                 if (command == 0) // Code 0: Prep for VRAM Read
                 {
                     _readBuffer = VRAM[_controlWord & 0x3FFF];
-                    _controlWord++;
+                    IncrementVdpAddress();
                 }
                 else if (command == 2) // Code 2: Write to Internal VDP Register
                 {
@@ -102,12 +116,42 @@ namespace Core.Video
             }
         }
 
+        private void IncrementVdpAddress()
+        {
+            // The VDP address register is only 14 bits
+            // When it increments past 0x3FFF, it rolls over to 0x0000.
+            // It can't overflow and corrupt the 2-bit command register (bits 14 and 15).
+            ushort address = (ushort)(_controlWord & 0x3FFF);
+            ushort command = (ushort)(_controlWord & 0xC000);
+
+            address = (ushort)((address + 1) & 0x3FFF);
+            _controlWord = (ushort)(command | address);
+        }
+
         public byte ReadVCounter()
         {
-            // Note: On real NTSC hardware, the V-Counter jumps slightly around 
-            // the VBlank period to keep the math 8-bit, but simply returning 
-            // the raw current scanline is perfectly fine to get us booting!
-            return (byte)_currentScanline;
+             // NTSC Math: 262 lines. Counts 0 to 218, jumps to 213 (0xD5), counts to 255.
+                if (_currentScanline <= 218) return (byte)_currentScanline;
+                else return (byte)(_currentScanline - 6);
+            
+        }
+        public byte ReadHCounter()
+        {
+            // The Master System H-Counter counts from 0x00 to 0x93, then jumps forward to 0xE9, ending at 0xFF.
+
+            // 1 T-State = 1.5 pixels. The H-Counter increments every 2 pixels.
+            // So H = T * 0.75
+            int h = (int)(_tStateCounter * 0.75);
+
+            if (h <= 0x93)
+            {
+                return (byte)h;
+            }
+            else
+            {
+                // Emulate the hardware jump!
+                return (byte)(h - 0x94 + 0xE9);
+            }
         }
 
         public void Update(int tStates)
@@ -145,7 +189,9 @@ namespace Core.Video
                 // 3. MOVE TO THE NEXT LINE
                 _currentScanline++;
 
-                if (_currentScanline > 261)
+                int maxLines = 262;
+
+                if (_currentScanline > maxLines -1)
                 {
                     _currentScanline = 0;
                 }
@@ -167,7 +213,6 @@ namespace Core.Video
                 for (int x = 0; x < 256; x++) FrameBuffer[(screenY * 256) + x] = unchecked((int)0xFF000000);
                 return;
             }
-
             // --- 1. RENDER BACKGROUND LINE ---
             ushort nameTableBase = (ushort)((Registers[2] & 0x0E) << 10);
             int scrollX = Registers[8]; 
@@ -183,16 +228,10 @@ namespace Core.Video
                 // --- LEFT COLUMN MASKING (OVERSCAN CURTAIN) ---
                 if (maskLeftCol && screenX < 8)
                 {
-                    // Draw the physical backdrop color (from Sprite Palette + Reg 7 index)
-                    byte bgSmsColor = CRAM[16 + (Registers[7] & 0x0F)];
-                    int bgR = (bgSmsColor & 0x03) * 85;
-                    int bgG = ((bgSmsColor >> 2) & 0x03) * 85;
-                    int bgB = ((bgSmsColor >> 4) & 0x03) * 85;
-
+                    // REPLACE THE R/G/B MATH WITH THIS SINGLE LINE:
                     int bgAddress = (screenY * 256) + screenX;
-                    FrameBuffer[bgAddress] = (255 << 24) | (bgR << 16) | (bgG << 8) | bgB;
+                    FrameBuffer[bgAddress] = GetRgbColour(16, Registers[7] & 0x0F);
 
-                    // Flag it as priority so sprites also hide behind the curtain!
                     _priorityBuffer[bgAddress] = true;
                     continue;
                 }
@@ -231,21 +270,17 @@ namespace Core.Video
                 byte bp3 = VRAM[tileAddress + (readY * 4) + 3];
 
                 int readX = flipH ? tileX : (7 - tileX);
-                int colorIndex = ((bp0 >> readX) & 1) | (((bp1 >> readX) & 1) << 1) |
+                int colourIndex = ((bp0 >> readX) & 1) | (((bp1 >> readX) & 1) << 1) |
                                  (((bp2 >> readX) & 1) << 2) | (((bp3 >> readX) & 1) << 3);
 
                 int paletteOffset = useSpritePalette ? 16 : 0;
-                byte smsColor = CRAM[paletteOffset + colorIndex];
-
-                int r = (smsColor & 0x03) * 85;
-                int g = ((smsColor >> 2) & 0x03) * 85;
-                int b = ((smsColor >> 4) & 0x03) * 85;
+                int finalColour = GetRgbColour(paletteOffset, colourIndex);
 
                 int screenAddress = (screenY * 256) + screenX;
 
                 // Draw background and reset priority mask for this exact pixel
-                FrameBuffer[screenAddress] = (255 << 24) | (r << 16) | (g << 8) | b;
-                _priorityBuffer[screenAddress] = (priority && colorIndex != 0);
+                FrameBuffer[screenAddress] = finalColour;
+                _priorityBuffer[screenAddress] = (priority && colourIndex != 0);
             }
 
             // --- 2. RENDER SPRITE LINE ---
@@ -299,24 +334,64 @@ namespace Core.Video
                     if (_priorityBuffer[(screenY * 256) + screenX]) continue;
 
                     int shift = 7 - px;
-                    int colorIndex = ((bp0 >> shift) & 1) | (((bp1 >> shift) & 1) << 1) |
+                    int colourIndex = ((bp0 >> shift) & 1) | (((bp1 >> shift) & 1) << 1) |
                                      (((bp2 >> shift) & 1) << 2) | (((bp3 >> shift) & 1) << 3);
 
-                    if (colorIndex == 0) continue;
+                    if (colourIndex == 0) continue;
 
-                    byte smsColor = CRAM[16 + colorIndex];
-                    int r = (smsColor & 0x03) * 85;
-                    int g = ((smsColor >> 2) & 0x03) * 85;
-                    int b = ((smsColor >> 4) & 0x03) * 85;
-
-                    FrameBuffer[(screenY * 256) + screenX] = (255 << 24) | (r << 16) | (g << 8) | b;
+                    // REPLACE THE R/G/B MATH WITH THIS SINGLE LINE:
+                    FrameBuffer[(screenY * 256) + screenX] = GetRgbColour(16, colourIndex);
                 }
             }
         }
+
+        public int GetRgbColour(int paletteOffset, int colourIndex)
+        {
+            //Debug.WriteLine(_isGameGear);
+            int r, g, b;
+
+            if (IsGameGear)
+            {
+                // Game Gear: 2 bytes per colour. Format: ----BBBBGGGGRRRR
+                int cramIndex = (paletteOffset + colourIndex) * 2;
+                ushort ggcolour = (ushort)(ggCRAM[cramIndex] | (ggCRAM[cramIndex + 1] << 8));
+
+                // Extract 4-bit values (0-15) and map them to standard 8-bit values (0-255). 
+                // We multiply by 17 because 255 / 15 = 17!
+                r = (ggcolour & 0x0F) * 17;
+                g = ((ggcolour >> 4) & 0x0F) * 17;
+                b = ((ggcolour >> 8) & 0x0F) * 17;
+            }
+            else
+            {
+                // Master System: 1 byte per colour. Format: --BBGGRR
+                byte smscolour = smsCRAM[paletteOffset + colourIndex];
+
+                // Extract 2-bit values (0-3) and map them to standard 8-bit values (0-255).
+                // We multiply by 85 because 255 / 3 = 85!
+                r = (smscolour & 0x03) * 85;
+                g = ((smscolour >> 2) & 0x03) * 85;
+                b = ((smscolour >> 4) & 0x03) * 85;
+            }
+
+            return (255 << 24) | (r << 16) | (g << 8) | b;
+        }
+
+        public void Reset()
+        {
+            _tStateCounter = 0;
+            _currentScanline = 0;
+            _lineCounter = 0;
+            _statusRegister = 0x00;
+            _controlWord = 0;
+            _isSecondControlByte = false;
+            _readBuffer = 0;
+        }
         public void SaveState(BinaryWriter bw)
         {
             bw.Write(VRAM);
-            bw.Write(CRAM);
+            bw.Write(smsCRAM);
+            bw.Write(ggCRAM);
             bw.Write(Registers);
             bw.Write(_isSecondControlByte);
             bw.Write(_controlWord);
@@ -329,12 +404,14 @@ namespace Core.Video
             // ADD THESE:
             bw.Write(_latchedHScroll);
             bw.Write(_latchedVScroll);
+            bw.Write(IsGameGear);
         }
 
         public void LoadState(BinaryReader br)
         {
             Array.Copy(br.ReadBytes(VRAM.Length), VRAM, VRAM.Length);
-            Array.Copy(br.ReadBytes(CRAM.Length), CRAM, CRAM.Length);
+            Array.Copy(br.ReadBytes(smsCRAM.Length), smsCRAM, smsCRAM.Length);
+            Array.Copy(br.ReadBytes(ggCRAM.Length), ggCRAM, ggCRAM.Length);
             Array.Copy(br.ReadBytes(Registers.Length), Registers, Registers.Length);
             _isSecondControlByte = br.ReadBoolean();
             _controlWord = br.ReadUInt16();
@@ -347,6 +424,7 @@ namespace Core.Video
             // ADD THESE:
             _latchedHScroll = br.ReadInt32();
             _latchedVScroll = br.ReadInt32();
+            IsGameGear = br.ReadBoolean();
         }
     }
 }

Desktop/DebuggerForm.Designer.cs

@@ -56,102 +56,104 @@
             lblFPS = new Label();
             lblFrameTime = new Label();
             richTextBox1 = new RichTextBox();
-            button1 = new Button();
+            btnCpuStep = new Button();
             CpuRun = new Button();
             groupBox1 = new GroupBox();
-            lblTone0 = new Label();
-            lblNoise = new Label();
-            lblTone2 = new Label();
             lblTone1 = new Label();
+            lblTone2 = new Label();
+            lblNoise = new Label();
+            lblTone0 = new Label();
+            lblHalt = new Label();
+            lblR = new Label();
             groupBox1.SuspendLayout();
             SuspendLayout();
             // 
             // lblAF
             // 
             lblAF.AutoSize = true;
-            lblAF.Location = new Point(12, 9);
+            lblAF.Location = new Point(10, 7);
             lblAF.Margin = new Padding(2, 0, 2, 0);
             lblAF.Name = "lblAF";
-            lblAF.Size = new Size(33, 25);
+            lblAF.Size = new Size(26, 20);
             lblAF.TabIndex = 0;
             lblAF.Text = "AF";
             // 
             // lblBC
             // 
             lblBC.AutoSize = true;
-            lblBC.Location = new Point(11, 60);
+            lblBC.Location = new Point(9, 48);
             lblBC.Margin = new Padding(2, 0, 2, 0);
             lblBC.Name = "lblBC";
-            lblBC.Size = new Size(33, 25);
+            lblBC.Size = new Size(27, 20);
             lblBC.TabIndex = 1;
             lblBC.Text = "BC";
             // 
             // lblDE
             // 
             lblDE.AutoSize = true;
-            lblDE.Location = new Point(12, 125);
+            lblDE.Location = new Point(10, 100);
             lblDE.Margin = new Padding(2, 0, 2, 0);
             lblDE.Name = "lblDE";
-            lblDE.Size = new Size(34, 25);
+            lblDE.Size = new Size(28, 20);
             lblDE.TabIndex = 2;
             lblDE.Text = "DE";
             // 
             // lblHL
             // 
             lblHL.AutoSize = true;
-            lblHL.Location = new Point(12, 188);
+            lblHL.Location = new Point(10, 150);
             lblHL.Margin = new Padding(2, 0, 2, 0);
             lblHL.Name = "lblHL";
-            lblHL.Size = new Size(33, 25);
+            lblHL.Size = new Size(27, 20);
             lblHL.TabIndex = 3;
             lblHL.Text = "HL";
             // 
             // lblPC
             // 
             lblPC.AutoSize = true;
-            lblPC.Location = new Point(11, 250);
+            lblPC.Location = new Point(9, 200);
             lblPC.Margin = new Padding(2, 0, 2, 0);
             lblPC.Name = "lblPC";
-            lblPC.Size = new Size(33, 25);
+            lblPC.Size = new Size(26, 20);
             lblPC.TabIndex = 4;
             lblPC.Text = "PC";
             // 
             // lblSP
             // 
             lblSP.AutoSize = true;
-            lblSP.Location = new Point(11, 315);
+            lblSP.Location = new Point(9, 252);
             lblSP.Margin = new Padding(2, 0, 2, 0);
             lblSP.Name = "lblSP";
-            lblSP.Size = new Size(32, 25);
+            lblSP.Size = new Size(25, 20);
             lblSP.TabIndex = 6;
             lblSP.Text = "SP";
             // 
             // lblFlags
             // 
             lblFlags.AutoSize = true;
-            lblFlags.Location = new Point(110, 65);
+            lblFlags.Location = new Point(88, 52);
             lblFlags.Margin = new Padding(2, 0, 2, 0);
             lblFlags.Name = "lblFlags";
-            lblFlags.Size = new Size(53, 25);
+            lblFlags.Size = new Size(43, 20);
             lblFlags.TabIndex = 7;
             lblFlags.Text = "Flags";
             // 
             // lblTStates
             // 
             lblTStates.AutoSize = true;
-            lblTStates.Location = new Point(110, 9);
+            lblTStates.Location = new Point(88, 7);
             lblTStates.Margin = new Padding(2, 0, 2, 0);
             lblTStates.Name = "lblTStates";
-            lblTStates.Size = new Size(75, 25);
+            lblTStates.Size = new Size(63, 20);
             lblTStates.TabIndex = 8;
             lblTStates.Text = "T-States";
             // 
             // txtMemoryStart
             // 
-            txtMemoryStart.Location = new Point(375, 26);
+            txtMemoryStart.Location = new Point(300, 21);
             txtMemoryStart.Margin = new Padding(2);
             txtMemoryStart.Name = "txtMemoryStart";
-            txtMemoryStart.Size = new Size(150, 31);
+            txtMemoryStart.Size = new Size(121, 27);
             txtMemoryStart.TabIndex = 9;
             txtMemoryStart.Text = "Memory Start";
             txtMemoryStart.TextAlign = HorizontalAlignment.Center;
@@ -159,10 +161,10 @@
             // 
             // btnRefreshMemory
             // 
-            btnRefreshMemory.Location = new Point(531, 26);
+            btnRefreshMemory.Location = new Point(425, 21);
             btnRefreshMemory.Margin = new Padding(2);
             btnRefreshMemory.Name = "btnRefreshMemory";
-            btnRefreshMemory.Size = new Size(112, 34);
+            btnRefreshMemory.Size = new Size(90, 27);
             btnRefreshMemory.TabIndex = 14;
             btnRefreshMemory.Text = "Refresh Memory";
             btnRefreshMemory.UseVisualStyleBackColor = true;
@@ -170,117 +172,109 @@
             // 
             // txtMemoryView
             // 
-            txtMemoryView.Location = new Point(110, 101);
+            txtMemoryView.Location = new Point(88, 81);
             txtMemoryView.Margin = new Padding(2);
             txtMemoryView.Name = "txtMemoryView";
-            txtMemoryView.Size = new Size(553, 543);
+            txtMemoryView.Size = new Size(443, 435);
             txtMemoryView.TabIndex = 15;
             txtMemoryView.Text = "Memory View Window";
             // 
             // lstDisassembly
             // 
             lstDisassembly.FormattingEnabled = true;
-            lstDisassembly.ItemHeight = 25;
-            lstDisassembly.Location = new Point(709, 10);
+            lstDisassembly.Location = new Point(567, 8);
             lstDisassembly.Margin = new Padding(2);
             lstDisassembly.Name = "lstDisassembly";
-            lstDisassembly.Size = new Size(314, 329);
+            lstDisassembly.Size = new Size(252, 264);
             lstDisassembly.TabIndex = 16;
             // 
             // lstStack
             // 
             lstStack.FormattingEnabled = true;
-            lstStack.ItemHeight = 25;
-            lstStack.Location = new Point(1029, 10);
+            lstStack.Location = new Point(823, 8);
             lstStack.Margin = new Padding(2);
             lstStack.Name = "lstStack";
-            lstStack.Size = new Size(162, 329);
+            lstStack.Size = new Size(130, 264);
             lstStack.TabIndex = 17;
             // 
             // label1
             // 
             label1.AutoSize = true;
-            label1.Location = new Point(710, 372);
-            label1.Margin = new Padding(4, 0, 4, 0);
+            label1.Location = new Point(568, 298);
             label1.Name = "label1";
-            label1.Size = new Size(97, 25);
+            label1.Size = new Size(81, 20);
             label1.TabIndex = 19;
             label1.Text = "Breakpoint";
             // 
             // txtBreakpoint
             // 
-            txtBreakpoint.Location = new Point(819, 369);
-            txtBreakpoint.Margin = new Padding(4);
+            txtBreakpoint.Location = new Point(655, 295);
             txtBreakpoint.Name = "txtBreakpoint";
-            txtBreakpoint.Size = new Size(155, 31);
+            txtBreakpoint.Size = new Size(125, 27);
             txtBreakpoint.TabIndex = 20;
             // 
             // label2
             // 
             label2.AutoSize = true;
-            label2.Location = new Point(291, 26);
-            label2.Margin = new Padding(4, 0, 4, 0);
+            label2.Location = new Point(233, 21);
             label2.Name = "label2";
-            label2.Size = new Size(77, 25);
+            label2.Size = new Size(62, 20);
             label2.TabIndex = 21;
             label2.Text = "Address";
             // 
             // lblIX
             // 
             lblIX.AutoSize = true;
-            lblIX.Location = new Point(11, 372);
+            lblIX.Location = new Point(9, 298);
             lblIX.Margin = new Padding(2, 0, 2, 0);
             lblIX.Name = "lblIX";
-            lblIX.Size = new Size(28, 25);
+            lblIX.Size = new Size(22, 20);
             lblIX.TabIndex = 22;
             lblIX.Text = "IX";
             // 
             // lblIY
             // 
             lblIY.AutoSize = true;
-            lblIY.Location = new Point(12, 430);
+            lblIY.Location = new Point(10, 344);
             lblIY.Margin = new Padding(2, 0, 2, 0);
             lblIY.Name = "lblIY";
-            lblIY.Size = new Size(27, 25);
+            lblIY.Size = new Size(21, 20);
             lblIY.TabIndex = 23;
             lblIY.Text = "IY";
             // 
             // lblIff1
             // 
             lblIff1.AutoSize = true;
-            lblIff1.Location = new Point(11, 533);
-            lblIff1.Margin = new Padding(4, 0, 4, 0);
+            lblIff1.Location = new Point(10, 472);
             lblIff1.Name = "lblIff1";
-            lblIff1.Size = new Size(45, 25);
+            lblIff1.Size = new Size(35, 20);
             lblIff1.TabIndex = 24;
             lblIff1.Text = "IFF1";
             // 
             // lblIff2
             // 
             lblIff2.AutoSize = true;
-            lblIff2.Location = new Point(11, 586);
-            lblIff2.Margin = new Padding(4, 0, 4, 0);
+            lblIff2.Location = new Point(10, 515);
             lblIff2.Name = "lblIff2";
-            lblIff2.Size = new Size(45, 25);
+            lblIff2.Size = new Size(35, 20);
             lblIff2.TabIndex = 25;
             lblIff2.Text = "IFF2";
             // 
             // lblIE
             // 
             lblIE.AutoSize = true;
-            lblIE.Location = new Point(11, 486);
-            lblIE.Margin = new Padding(4, 0, 4, 0);
+            lblIE.Location = new Point(10, 435);
             lblIE.Name = "lblIE";
-            lblIE.Size = new Size(33, 25);
+            lblIE.Size = new Size(26, 20);
             lblIE.TabIndex = 26;
             lblIE.Text = "IM";
             // 
             // btnReset
             // 
-            btnReset.Location = new Point(814, 409);
+            btnReset.Location = new Point(651, 327);
             btnReset.Margin = new Padding(2);
             btnReset.Name = "btnReset";
-            btnReset.Size = new Size(165, 34);
+            btnReset.Size = new Size(132, 27);
             btnReset.TabIndex = 27;
             btnReset.Text = "Set Breakpoint";
             btnReset.UseVisualStyleBackColor = true;
@@ -295,61 +289,58 @@
             // lblFrames
             // 
             lblFrames.AutoSize = true;
-            lblFrames.Location = new Point(14, 660);
+            lblFrames.Location = new Point(10, 605);
             lblFrames.Margin = new Padding(2, 0, 2, 0);
             lblFrames.Name = "lblFrames";
-            lblFrames.Size = new Size(149, 25);
+            lblFrames.Size = new Size(124, 20);
             lblFrames.TabIndex = 28;
             lblFrames.Text = "Frames Rendered";
             // 
             // lblFPS
             // 
             lblFPS.AutoSize = true;
-            lblFPS.Location = new Point(129, 757);
+            lblFPS.Location = new Point(102, 683);
             lblFPS.Margin = new Padding(2, 0, 2, 0);
             lblFPS.Name = "lblFPS";
-            lblFPS.Size = new Size(41, 25);
+            lblFPS.Size = new Size(32, 20);
             lblFPS.TabIndex = 29;
             lblFPS.Text = "FPS";
             // 
             // lblFrameTime
             // 
             lblFrameTime.AutoSize = true;
-            lblFrameTime.Location = new Point(60, 706);
+            lblFrameTime.Location = new Point(47, 642);
             lblFrameTime.Margin = new Padding(2, 0, 2, 0);
             lblFrameTime.Name = "lblFrameTime";
-            lblFrameTime.Size = new Size(104, 25);
+            lblFrameTime.Size = new Size(87, 20);
             lblFrameTime.TabIndex = 30;
             lblFrameTime.Text = "Frame Time";
             // 
             // richTextBox1
             // 
             richTextBox1.Enabled = false;
-            richTextBox1.Location = new Point(682, 474);
-            richTextBox1.Margin = new Padding(4);
+            richTextBox1.Location = new Point(546, 379);
             richTextBox1.Name = "richTextBox1";
             richTextBox1.ReadOnly = true;
-            richTextBox1.Size = new Size(379, 159);
+            richTextBox1.Size = new Size(304, 128);
             richTextBox1.TabIndex = 32;
             richTextBox1.Text = "Sega Master System Memory Map:\n0x0000 - 0x3FFF: ROM Slot 0 (16KB)\n0x4000 - 0x7FFF: ROM Slot 1 (16KB)\n0x8000 - 0xBFFF: ROM Slot 2 (16KB)\n0xC000 - 0xDFFF: System RAM (8KB)\n0xE000 - 0xFFFF: RAM Mirror";
             // 
-            // button1
+            // btnCpuStep
             // 
-            button1.Location = new Point(1075, 756);
-            button1.Margin = new Padding(4);
-            button1.Name = "button1";
-            button1.Size = new Size(118, 36);
-            button1.TabIndex = 33;
-            button1.Text = "CPU Step";
-            button1.UseVisualStyleBackColor = true;
-            button1.Click += btnStep_Click;
+            btnCpuStep.Location = new Point(860, 605);
+            btnCpuStep.Name = "btnCpuStep";
+            btnCpuStep.Size = new Size(94, 29);
+            btnCpuStep.TabIndex = 33;
+            btnCpuStep.Text = "CPU Step";
+            btnCpuStep.UseVisualStyleBackColor = true;
+            btnCpuStep.Click += btnStep_Click;
             // 
             // CpuRun
             // 
-            CpuRun.Location = new Point(943, 757);
-            CpuRun.Margin = new Padding(4);
+            CpuRun.Location = new Point(754, 606);
             CpuRun.Name = "CpuRun";
-            CpuRun.Size = new Size(118, 36);
+            CpuRun.Size = new Size(94, 29);
             CpuRun.TabIndex = 34;
             CpuRun.Text = "CPU Run";
             CpuRun.UseVisualStyleBackColor = true;
@@ -361,57 +352,83 @@
             groupBox1.Controls.Add(lblTone2);
             groupBox1.Controls.Add(lblNoise);
             groupBox1.Controls.Add(lblTone0);
-            groupBox1.Location = new Point(266, 658);
+            groupBox1.Location = new Point(213, 526);
+            groupBox1.Margin = new Padding(2);
             groupBox1.Name = "groupBox1";
-            groupBox1.Size = new Size(397, 222);
+            groupBox1.Padding = new Padding(2);
+            groupBox1.Size = new Size(318, 178);
             groupBox1.TabIndex = 35;
             groupBox1.TabStop = false;
             groupBox1.Text = "Audio (SN76489)";
             // 
-            // lblTone0
+            // lblTone1
             // 
-            lblTone0.AutoSize = true;
-            lblTone0.Location = new Point(25, 48);
-            lblTone0.Name = "lblTone0";
-            lblTone0.Size = new Size(59, 25);
-            lblTone0.TabIndex = 0;
-            lblTone0.Text = "Tone0";
-            // 
-            // lblNoise
-            // 
-            lblNoise.AutoSize = true;
-            lblNoise.Location = new Point(25, 160);
-            lblNoise.Name = "lblNoise";
-            lblNoise.Size = new Size(57, 25);
-            lblNoise.TabIndex = 1;
-            lblNoise.Text = "Noise";
+            lblTone1.AutoSize = true;
+            lblTone1.Location = new Point(20, 66);
+            lblTone1.Margin = new Padding(2, 0, 2, 0);
+            lblTone1.Name = "lblTone1";
+            lblTone1.Size = new Size(49, 20);
+            lblTone1.TabIndex = 3;
+            lblTone1.Text = "Tone1";
             // 
             // lblTone2
             // 
             lblTone2.AutoSize = true;
-            lblTone2.Location = new Point(25, 122);
+            lblTone2.Location = new Point(20, 98);
+            lblTone2.Margin = new Padding(2, 0, 2, 0);
             lblTone2.Name = "lblTone2";
-            lblTone2.Size = new Size(59, 25);
+            lblTone2.Size = new Size(49, 20);
             lblTone2.TabIndex = 2;
             lblTone2.Text = "Tone2";
             // 
-            // lblTone1
+            // lblNoise
             // 
-            lblTone1.AutoSize = true;
-            lblTone1.Location = new Point(25, 83);
-            lblTone1.Name = "lblTone1";
-            lblTone1.Size = new Size(59, 25);
-            lblTone1.TabIndex = 3;
-            lblTone1.Text = "Tone1";
+            lblNoise.AutoSize = true;
+            lblNoise.Location = new Point(20, 128);
+            lblNoise.Margin = new Padding(2, 0, 2, 0);
+            lblNoise.Name = "lblNoise";
+            lblNoise.Size = new Size(47, 20);
+            lblNoise.TabIndex = 1;
+            lblNoise.Text = "Noise";
+            // 
+            // lblTone0
+            // 
+            lblTone0.AutoSize = true;
+            lblTone0.Location = new Point(20, 38);
+            lblTone0.Margin = new Padding(2, 0, 2, 0);
+            lblTone0.Name = "lblTone0";
+            lblTone0.Size = new Size(49, 20);
+            lblTone0.TabIndex = 0;
+            lblTone0.Text = "Tone0";
+            // 
+            // lblHalt
+            // 
+            lblHalt.AutoSize = true;
+            lblHalt.Location = new Point(9, 564);
+            lblHalt.Name = "lblHalt";
+            lblHalt.Size = new Size(37, 20);
+            lblHalt.TabIndex = 36;
+            lblHalt.Text = "Halt";
+            // 
+            // lblR
+            // 
+            lblR.AutoSize = true;
+            lblR.Location = new Point(9, 392);
+            lblR.Name = "lblR";
+            lblR.Size = new Size(18, 20);
+            lblR.TabIndex = 37;
+            lblR.Text = "R";
             // 
             // DebuggerForm
             // 
-            AutoScaleDimensions = new SizeF(10F, 25F);
+            AutoScaleDimensions = new SizeF(8F, 20F);
             AutoScaleMode = AutoScaleMode.Font;
-            ClientSize = new Size(1206, 892);
+            ClientSize = new Size(965, 714);
+            Controls.Add(lblR);
+            Controls.Add(lblHalt);
             Controls.Add(groupBox1);
             Controls.Add(CpuRun);
-            Controls.Add(button1);
+            Controls.Add(btnCpuStep);
             Controls.Add(richTextBox1);
             Controls.Add(lblFrameTime);
             Controls.Add(lblFPS);
@@ -475,7 +492,7 @@
         private Label lblFPS;
         private Label lblFrameTime;
         private RichTextBox richTextBox1;
-        private Button button1;
+        private Button btnCpuStep;
         private Button CpuRun;
         public System.Windows.Forms.Timer uiUpdateTimer;
         private GroupBox groupBox1;
@@ -483,6 +500,8 @@
         private Label lblTone2;
         private Label lblNoise;
         private Label lblTone0;
+        private Label lblHalt;
+        private Label lblR;
         //private TextBox textBox4;
     }
 }

Desktop/DebuggerForm.cs

@@ -27,6 +27,7 @@ namespace Desktop
             UpdateStackView();
             UpdateDisassemblyView();
             _mainForm = mainForm;
+            CpuRun.Text = _mainForm.IsRunning ? "CPU Stop" : "CPU Run";
         }
 
         private void CpuRun_Click(object sender, EventArgs e)
@@ -35,7 +36,6 @@ namespace Desktop
             {
                 // Stop the machine
                 _mainForm.StopEmulator();
-                CpuRun.Text = "CPU Run";
 
                 // Stop the live UI updates and do one final manual refresh
                 uiUpdateTimer.Stop();
@@ -45,12 +45,12 @@ namespace Desktop
             {
                 // Start the machine
                 _mainForm.StartEmulator();
-                CpuRun.Text = "CPU Stop";
 
                 // Start the timer so the debugger screen updates automatically
                 // (Make sure your uiUpdateTimer Interval in the designer is set to something like 100ms)
                 uiUpdateTimer.Start();
             }
+            CpuRun.Text = _mainForm.IsRunning ? "CPU Stop" : "CPU Run";
         }
 
         private void btnStep_Click(object sender, EventArgs e)
@@ -92,6 +92,8 @@ namespace Desktop
         // Current Emulator State
         private void UpdateDisplay()
         {
+            CpuRun.Text = _mainForm.IsRunning ? "CPU Stop" : "CPU Run";
+            btnCpuStep.Enabled = _mainForm.IsRunning ? false : true;
             lblAF.Text = $"AF: {_cpu.AF.Word:X4}";
             lblBC.Text = $"BC: {_cpu.BC.Word:X4}";
             lblDE.Text = $"DE: {_cpu.DE.Word:X4}";
@@ -108,11 +110,12 @@ namespace Desktop
             lblFrames.Text = $"Frames Rendered: {_mainForm.TotalFrameCount}";
             lblFrameTime.Text = $"Frame Time: {((float)_mainForm.FrameTime):F1}ms";
             lblFPS.Text = $"FPS: {_mainForm.FramesPerSecond:F2}";
+            lblHalt.Text = $"CPU Halted: {_cpu.IsHalted}";
+            lblR.Text = $"R: {_cpu.R:X2}";
             UpdateMemoryView();
             UpdateStackView();
             UpdateDisassemblyView();
-            // --- AUDIO REGISTERS ---
-            // Use _mainForm to access the Machine, and then grab the AudioProcessor!
+            // --- AUDIO REGISTERS ---//
             if (_mainForm._machine != null && _mainForm._machine.AudioProcessor != null)
             {
                 ushort[] apuRegs = _mainForm._machine.AudioProcessor.Registers;
@@ -666,6 +669,9 @@ namespace Desktop
                     case 0xC9:
                         mnemonic = "RET";
                         break;
+                    case 0x76:
+                        mnemonic = "HALT!";
+                        break;
                     case 0xCB:
                         cbOp = _memoryBus.Read((ushort)(currentPc + 1));
 

Desktop/Desktop.csproj

@@ -14,11 +14,20 @@
 		<IncludeNativeLibrariesForSelfExtract>true</IncludeNativeLibrariesForSelfExtract>
 		<RuntimeIdentifier>win-x64</RuntimeIdentifier>
 		<StartupObject>Desktop.Program</StartupObject>
-		<AssemblyName>Parsons Master System</AssemblyName>
+		<AssemblyName>Parsons Master System 2026</AssemblyName>
+		<ApplicationIcon>favicon.ico</ApplicationIcon>
+		<Title>Sega Master System EMulator 2026</Title>
+		<Version>1.0</Version>
+		<Authors>Marc Parsons</Authors>
+		<Company>Parsons Limited</Company>
+		<Description>Parsons Master System 2026</Description>
+		<Copyright>Copyright 2026 Marc Parsons</Copyright>
+		<PackageIcon>logo1.bmp</PackageIcon>
 	</PropertyGroup>
 
 	<ItemGroup>
 		<None Remove="ROMS\After Burner %28UE%29 [!].sms" />
+		<None Remove="ROMS\Aladdin %28USA, Europe, Brazil%29.gg" />
 		<None Remove="ROMS\Alex Kidd in High Tech World %28UE%29 [!].sms" />
 		<None Remove="ROMS\Alex Kidd in Miracle World %28UE%29 [!].sms" />
 		<None Remove="ROMS\Back to the Future 2 %28UE%29 [!].sms" />
@@ -26,6 +35,7 @@
 		<None Remove="ROMS\Bart vs. the Space Mutants %28UE%29 [!].sms" />
 		<None Remove="ROMS\Bart vs. the World %28UE%29 [!].sms" />
 		<None Remove="ROMS\Black Belt %28UE%29 [!].sms" />
+		<None Remove="ROMS\Bonanza Bros. %28Europe%29.sms" />
 		<None Remove="ROMS\California Games %28UE%29 [!].sms" />
 		<None Remove="ROMS\California Games 2 %28UE%29 [!].sms" />
 		<None Remove="ROMS\Casino Games %28UE%29 [!].sms" />
@@ -42,9 +52,10 @@
 		<None Remove="ROMS\Gangster Town %28UE%29 [!].sms" />
 		<None Remove="ROMS\Gauntlet %28UE%29 [!].sms" />
 		<None Remove="ROMS\Ghost House %28UE%29 [!].sms" />
-		<None Remove="ROMS\Ghouls %27n Ghosts %28UE%29 [!].sms" />
+		<None Remove="ROMS\Ghouls %27n Ghosts %28USA%29.sms" />
 		<None Remove="ROMS\Global Defense %28UE%29 [!].sms" />
 		<None Remove="ROMS\Golden Axe %28UE%29 [!].sms" />
+		<None Remove="ROMS\Golden Axe Warrior.sav" />
 		<None Remove="ROMS\Golden Axe Warrior.sms" />
 		<None Remove="ROMS\Great Baseball %28UE%29 [!].sms" />
 		<None Remove="ROMS\Great Basketball %28UE%29 [!].sms" />
@@ -59,17 +70,21 @@
 		<None Remove="ROMS\Impossible Mission %28UE%29 [!].sms" />
 		<None Remove="ROMS\Japanese SMS BIOS v2.1 %28J%29 [!].sms" />
 		<None Remove="ROMS\Jurassic Park %28UE%29 [!].sms" />
+		<None Remove="ROMS\Lucky Dime Caper Starring Donald Duck, The %28Europe, Brazil%29 %28En%29.sms" />
 		<None Remove="ROMS\Mickey Mouse - Castle of Illusion %28UE%29 [!].sms" />
 		<None Remove="ROMS\Mickey Mouse - Land of Illusion %28UE%29 [!].sms" />
 		<None Remove="ROMS\Mickey Mouse - Legend of Illusion %28UE%29 [!].sms" />
+		<None Remove="ROMS\Micro Machines %28Europe%29.sms" />
 		<None Remove="ROMS\Mortal Kombat %28UE%29 [!].sms" />
 		<None Remove="ROMS\Mortal Kombat 2 %28UE%29 [!].sms" />
 		<None Remove="ROMS\Mortal Kombat 3 %28UE%29 [!].sms" />
-		<None Remove="ROMS\OutRun %28UE%29 [!].sms" />
+		<None Remove="ROMS\Olympic Gold - Barcelona %2792 %28Europe%29.sms" />
+		<None Remove="ROMS\OutRun %28USA%29.sms" />
 		<None Remove="ROMS\Paperboy %28UE%29 [!].sms" />
 		<None Remove="ROMS\Parlour Games %28UE%29 [!].sms" />
 		<None Remove="ROMS\Phantasy Star %28UE%29 [!].sms" />
 		<None Remove="ROMS\Populous %28UE%29 [!].sms" />
+		<None Remove="ROMS\Prince of Persia %28Europe%29.sms" />
 		<None Remove="ROMS\Psychic World %28UE%29 [!].sms" />
 		<None Remove="ROMS\Psycho Fox %28UE%29 [!].sms" />
 		<None Remove="ROMS\R-Type.sms" />
@@ -77,10 +92,13 @@
 		<None Remove="ROMS\Shadow of the Beast %28UE%29 [!].sms" />
 		<None Remove="ROMS\Smash TV %28UE%29 [!].sms" />
 		<None Remove="ROMS\SMSTestSuite.sms" />
+		<None Remove="ROMS\Sonic 1 GG.gg" />
 		<None Remove="ROMS\Sonic 2.sms" />
 		<None Remove="ROMS\Sonic Chaos %28UE%29 [!].sms" />
+		<None Remove="ROMS\Sonic The Hedgehog - Triple Trouble %28USA, Europe, Brazil%29.gg" />
+		<None Remove="ROMS\Sonic The Hedgehog 2 %28World%29.gg" />
 		<None Remove="ROMS\Sonic.sms" />
-		<None Remove="ROMS\Space Harrier %28UE%29 [!].sms" />
+		<None Remove="ROMS\Space Harrier %28USA%29.sms" />
 		<None Remove="ROMS\Speedball %28UE%29 %28Virgin%29 [!].sms" />
 		<None Remove="ROMS\Star Wars %28UE%29 [!].sms" />
 		<None Remove="ROMS\Street Fighter 2 %28Brazil%29 [!].sms" />
@@ -103,10 +121,15 @@
 		<None Remove="ROMS\zexdoc.sms" />
 	</ItemGroup>
 
+	<ItemGroup>
+	  <Content Include="favicon.ico" />
+	</ItemGroup>
+
 	<ItemGroup>
 		<EmbeddedResource Include="ROMS\After Burner (UE) [!].sms">
 			<CopyToOutputDirectory>Never</CopyToOutputDirectory>
 		</EmbeddedResource>
+		<EmbeddedResource Include="ROMS\Aladdin (USA, Europe, Brazil).gg" />
 		<EmbeddedResource Include="ROMS\Alex Kidd in High Tech World (UE) [!].sms">
 			<CopyToOutputDirectory>Never</CopyToOutputDirectory>
 		</EmbeddedResource>
@@ -128,6 +151,7 @@
 		<EmbeddedResource Include="ROMS\Black Belt (UE) [!].sms">
 			<CopyToOutputDirectory>Never</CopyToOutputDirectory>
 		</EmbeddedResource>
+		<EmbeddedResource Include="ROMS\Bonanza Bros. (Europe).sms" />
 		<EmbeddedResource Include="ROMS\California Games (UE) [!].sms">
 			<CopyToOutputDirectory>Never</CopyToOutputDirectory>
 		</EmbeddedResource>
@@ -176,15 +200,14 @@
 		<EmbeddedResource Include="ROMS\Ghost House (UE) [!].sms">
 			<CopyToOutputDirectory>Never</CopyToOutputDirectory>
 		</EmbeddedResource>
-		<EmbeddedResource Include="ROMS\Ghouls 'n Ghosts (UE) [!].sms">
-			<CopyToOutputDirectory>Never</CopyToOutputDirectory>
-		</EmbeddedResource>
+		<EmbeddedResource Include="ROMS\Ghouls 'n Ghosts (USA).sms" />
 		<EmbeddedResource Include="ROMS\Global Defense (UE) [!].sms">
 			<CopyToOutputDirectory>Never</CopyToOutputDirectory>
 		</EmbeddedResource>
 		<EmbeddedResource Include="ROMS\Golden Axe (UE) [!].sms">
 			<CopyToOutputDirectory>Never</CopyToOutputDirectory>
 		</EmbeddedResource>
+		<EmbeddedResource Include="ROMS\Golden Axe Warrior.sav" />
 		<EmbeddedResource Include="ROMS\Golden Axe Warrior.sms">
 			<CopyToOutputDirectory>Never</CopyToOutputDirectory>
 		</EmbeddedResource>
@@ -227,6 +250,7 @@
 		<EmbeddedResource Include="ROMS\Jurassic Park (UE) [!].sms">
 			<CopyToOutputDirectory>Never</CopyToOutputDirectory>
 		</EmbeddedResource>
+		<EmbeddedResource Include="ROMS\Lucky Dime Caper Starring Donald Duck, The (Europe, Brazil) (En).sms" />
 		<EmbeddedResource Include="ROMS\Mickey Mouse - Castle of Illusion (UE) [!].sms">
 			<CopyToOutputDirectory>Never</CopyToOutputDirectory>
 		</EmbeddedResource>
@@ -236,6 +260,7 @@
 		<EmbeddedResource Include="ROMS\Mickey Mouse - Legend of Illusion (UE) [!].sms">
 			<CopyToOutputDirectory>Never</CopyToOutputDirectory>
 		</EmbeddedResource>
+		<EmbeddedResource Include="ROMS\Micro Machines (Europe).sms" />
 		<EmbeddedResource Include="ROMS\Mortal Kombat (UE) [!].sms">
 			<CopyToOutputDirectory>Never</CopyToOutputDirectory>
 		</EmbeddedResource>
@@ -245,9 +270,8 @@
 		<EmbeddedResource Include="ROMS\Mortal Kombat 3 (UE) [!].sms">
 			<CopyToOutputDirectory>Never</CopyToOutputDirectory>
 		</EmbeddedResource>
-		<EmbeddedResource Include="ROMS\OutRun (UE) [!].sms">
-			<CopyToOutputDirectory>Never</CopyToOutputDirectory>
-		</EmbeddedResource>
+		<EmbeddedResource Include="ROMS\Olympic Gold - Barcelona '92 (Europe).sms" />
+		<EmbeddedResource Include="ROMS\OutRun (USA).sms" />
 		<EmbeddedResource Include="ROMS\Paperboy (UE) [!].sms">
 			<CopyToOutputDirectory>Never</CopyToOutputDirectory>
 		</EmbeddedResource>
@@ -260,6 +284,7 @@
 		<EmbeddedResource Include="ROMS\Populous (UE) [!].sms">
 			<CopyToOutputDirectory>Never</CopyToOutputDirectory>
 		</EmbeddedResource>
+		<EmbeddedResource Include="ROMS\Prince of Persia (Europe).sms" />
 		<EmbeddedResource Include="ROMS\Psychic World (UE) [!].sms">
 			<CopyToOutputDirectory>Never</CopyToOutputDirectory>
 		</EmbeddedResource>
@@ -281,18 +306,19 @@
 		<EmbeddedResource Include="ROMS\SMSTestSuite.sms">
 			<CopyToOutputDirectory>Never</CopyToOutputDirectory>
 		</EmbeddedResource>
+		<EmbeddedResource Include="ROMS\Sonic 1 GG.gg" />
 		<EmbeddedResource Include="ROMS\Sonic 2.sms">
 			<CopyToOutputDirectory>Never</CopyToOutputDirectory>
 		</EmbeddedResource>
 		<EmbeddedResource Include="ROMS\Sonic Chaos (UE) [!].sms">
 			<CopyToOutputDirectory>Never</CopyToOutputDirectory>
 		</EmbeddedResource>
+		<EmbeddedResource Include="ROMS\Sonic The Hedgehog - Triple Trouble (USA, Europe, Brazil).gg" />
+		<EmbeddedResource Include="ROMS\Sonic The Hedgehog 2 (World).gg" />
 		<EmbeddedResource Include="ROMS\Sonic.sms">
 			<CopyToOutputDirectory>Never</CopyToOutputDirectory>
 		</EmbeddedResource>
-		<EmbeddedResource Include="ROMS\Space Harrier (UE) [!].sms">
-			<CopyToOutputDirectory>Never</CopyToOutputDirectory>
-		</EmbeddedResource>
+		<EmbeddedResource Include="ROMS\Space Harrier (USA).sms" />
 		<EmbeddedResource Include="ROMS\Speedball (UE) (Virgin) [!].sms">
 			<CopyToOutputDirectory>Never</CopyToOutputDirectory>
 		</EmbeddedResource>
@@ -353,6 +379,13 @@
 		</EmbeddedResource>
 	</ItemGroup>
 
+	<ItemGroup>
+	  <None Include="..\logo1.bmp">
+	    <Pack>True</Pack>
+	    <PackagePath>\</PackagePath>
+	  </None>
+	</ItemGroup>
+
 	<ItemGroup>
 		<PackageReference Include="NAudio" Version="2.3.0" />
 		<PackageReference Include="Vortice.XInput" Version="3.8.3" />

Desktop/Form1.Designer.cs

@@ -32,6 +32,8 @@
             fileToolStripMenuItem = new ToolStripMenuItem();
             openToolStripMenuItem = new ToolStripMenuItem();
             includedToolStripMenuItem = new ToolStripMenuItem();
+            masterSystemToolStripMenuItem = new ToolStripMenuItem();
+            gameGearToolStripMenuItem = new ToolStripMenuItem();
             selectROMToolStripMenuItem1 = new ToolStripMenuItem();
             exitToolStripMenuItem = new ToolStripMenuItem();
             viewToolStripMenuItem = new ToolStripMenuItem();
@@ -39,10 +41,11 @@
             vRAMViewerToolStripMenuItem = new ToolStripMenuItem();
             machineToolStripMenuItem = new ToolStripMenuItem();
             resetToolStripMenuItem = new ToolStripMenuItem();
-            helpToolStripMenuItem = new ToolStripMenuItem();
-            aboutToolStripMenuItem = new ToolStripMenuItem();
             saveStateToolStripMenuItem = new ToolStripMenuItem();
             loadStateToolStripMenuItem = new ToolStripMenuItem();
+            turboModeToolStripMenuItem = new ToolStripMenuItem();
+            helpToolStripMenuItem = new ToolStripMenuItem();
+            aboutToolStripMenuItem = new ToolStripMenuItem();
             menuStrip1.SuspendLayout();
             SuspendLayout();
             // 
@@ -52,7 +55,8 @@
             menuStrip1.Items.AddRange(new ToolStripItem[] { fileToolStripMenuItem, viewToolStripMenuItem, machineToolStripMenuItem, helpToolStripMenuItem });
             menuStrip1.Location = new Point(0, 0);
             menuStrip1.Name = "menuStrip1";
-            menuStrip1.Size = new Size(791, 33);
+            menuStrip1.Padding = new Padding(5, 2, 0, 2);
+            menuStrip1.Size = new Size(633, 28);
             menuStrip1.TabIndex = 2;
             menuStrip1.Text = "menuStrip1";
             // 
@@ -60,34 +64,46 @@
             // 
             fileToolStripMenuItem.DropDownItems.AddRange(new ToolStripItem[] { openToolStripMenuItem, exitToolStripMenuItem });
             fileToolStripMenuItem.Name = "fileToolStripMenuItem";
-            fileToolStripMenuItem.Size = new Size(54, 29);
+            fileToolStripMenuItem.Size = new Size(46, 24);
             fileToolStripMenuItem.Text = "File";
             // 
             // openToolStripMenuItem
             // 
             openToolStripMenuItem.DropDownItems.AddRange(new ToolStripItem[] { includedToolStripMenuItem, selectROMToolStripMenuItem1 });
             openToolStripMenuItem.Name = "openToolStripMenuItem";
-            openToolStripMenuItem.Size = new Size(158, 34);
+            openToolStripMenuItem.Size = new Size(128, 26);
             openToolStripMenuItem.Text = "Open";
             // 
             // includedToolStripMenuItem
             // 
+            includedToolStripMenuItem.DropDownItems.AddRange(new ToolStripItem[] { masterSystemToolStripMenuItem, gameGearToolStripMenuItem });
             includedToolStripMenuItem.Name = "includedToolStripMenuItem";
-            includedToolStripMenuItem.Size = new Size(218, 34);
+            includedToolStripMenuItem.Size = new Size(178, 26);
             includedToolStripMenuItem.Text = "Included";
-            includedToolStripMenuItem.Click += includedToolStripMenuItem_Click;
+            // 
+            // masterSystemToolStripMenuItem
+            // 
+            masterSystemToolStripMenuItem.Name = "masterSystemToolStripMenuItem";
+            masterSystemToolStripMenuItem.Size = new Size(188, 26);
+            masterSystemToolStripMenuItem.Text = "Master System";
+            // 
+            // gameGearToolStripMenuItem
+            // 
+            gameGearToolStripMenuItem.Name = "gameGearToolStripMenuItem";
+            gameGearToolStripMenuItem.Size = new Size(188, 26);
+            gameGearToolStripMenuItem.Text = "Game Gear";
             // 
             // selectROMToolStripMenuItem1
             // 
             selectROMToolStripMenuItem1.Name = "selectROMToolStripMenuItem1";
-            selectROMToolStripMenuItem1.Size = new Size(218, 34);
+            selectROMToolStripMenuItem1.Size = new Size(178, 26);
             selectROMToolStripMenuItem1.Text = "Select ROM...";
             selectROMToolStripMenuItem1.Click += selectROMToolStripMenuItem_Click;
             // 
             // exitToolStripMenuItem
             // 
             exitToolStripMenuItem.Name = "exitToolStripMenuItem";
-            exitToolStripMenuItem.Size = new Size(158, 34);
+            exitToolStripMenuItem.Size = new Size(128, 26);
             exitToolStripMenuItem.Text = "Exit";
             exitToolStripMenuItem.Click += exitToolStripMenuItem_Click;
             // 
@@ -95,72 +111,79 @@
             // 
             viewToolStripMenuItem.DropDownItems.AddRange(new ToolStripItem[] { debuggerToolStripMenuItem, vRAMViewerToolStripMenuItem });
             viewToolStripMenuItem.Name = "viewToolStripMenuItem";
-            viewToolStripMenuItem.Size = new Size(65, 29);
+            viewToolStripMenuItem.Size = new Size(55, 24);
             viewToolStripMenuItem.Text = "View";
             // 
             // debuggerToolStripMenuItem
             // 
             debuggerToolStripMenuItem.Name = "debuggerToolStripMenuItem";
-            debuggerToolStripMenuItem.Size = new Size(221, 34);
+            debuggerToolStripMenuItem.Size = new Size(182, 26);
             debuggerToolStripMenuItem.Text = "Debugger";
             debuggerToolStripMenuItem.Click += debuggerToolStripMenuItem_Click;
             // 
             // vRAMViewerToolStripMenuItem
             // 
             vRAMViewerToolStripMenuItem.Name = "vRAMViewerToolStripMenuItem";
-            vRAMViewerToolStripMenuItem.Size = new Size(221, 34);
+            vRAMViewerToolStripMenuItem.Size = new Size(182, 26);
             vRAMViewerToolStripMenuItem.Text = "VRAM Viewer";
             vRAMViewerToolStripMenuItem.Click += vramViewerToolStripMenuItem_Click;
             // 
             // machineToolStripMenuItem
             // 
-            machineToolStripMenuItem.DropDownItems.AddRange(new ToolStripItem[] { resetToolStripMenuItem, saveStateToolStripMenuItem, loadStateToolStripMenuItem });
+            machineToolStripMenuItem.DropDownItems.AddRange(new ToolStripItem[] { resetToolStripMenuItem, saveStateToolStripMenuItem, loadStateToolStripMenuItem, turboModeToolStripMenuItem });
             machineToolStripMenuItem.Name = "machineToolStripMenuItem";
-            machineToolStripMenuItem.Size = new Size(94, 29);
+            machineToolStripMenuItem.Size = new Size(79, 24);
             machineToolStripMenuItem.Text = "Machine";
             // 
             // resetToolStripMenuItem
             // 
             resetToolStripMenuItem.Name = "resetToolStripMenuItem";
-            resetToolStripMenuItem.Size = new Size(270, 34);
+            resetToolStripMenuItem.Size = new Size(174, 26);
             resetToolStripMenuItem.Text = "Reset";
             resetToolStripMenuItem.Click += resetToolStripMenuItem_Click;
             // 
-            // helpToolStripMenuItem
-            // 
-            helpToolStripMenuItem.DropDownItems.AddRange(new ToolStripItem[] { aboutToolStripMenuItem });
-            helpToolStripMenuItem.Name = "helpToolStripMenuItem";
-            helpToolStripMenuItem.Size = new Size(65, 29);
-            helpToolStripMenuItem.Text = "Help";
-            // 
-            // aboutToolStripMenuItem
-            // 
-            aboutToolStripMenuItem.Name = "aboutToolStripMenuItem";
-            aboutToolStripMenuItem.Size = new Size(164, 34);
-            aboutToolStripMenuItem.Text = "About";
-            // 
             // saveStateToolStripMenuItem
             // 
             saveStateToolStripMenuItem.Name = "saveStateToolStripMenuItem";
-            saveStateToolStripMenuItem.Size = new Size(270, 34);
+            saveStateToolStripMenuItem.Size = new Size(174, 26);
             saveStateToolStripMenuItem.Text = "Save State";
             saveStateToolStripMenuItem.Click += saveStateToolStripMenuItem_Click;
             // 
             // loadStateToolStripMenuItem
             // 
             loadStateToolStripMenuItem.Name = "loadStateToolStripMenuItem";
-            loadStateToolStripMenuItem.Size = new Size(270, 34);
+            loadStateToolStripMenuItem.Size = new Size(174, 26);
             loadStateToolStripMenuItem.Text = "Load State";
             loadStateToolStripMenuItem.Click += loadStateToolStripMenuItem_Click;
             // 
+            // turboModeToolStripMenuItem
+            // 
+            turboModeToolStripMenuItem.Name = "turboModeToolStripMenuItem";
+            turboModeToolStripMenuItem.Size = new Size(174, 26);
+            turboModeToolStripMenuItem.Text = "Turbo Mode";
+            turboModeToolStripMenuItem.Click += turboModeToolStripMenuItem_Click;
+            // 
+            // helpToolStripMenuItem
+            // 
+            helpToolStripMenuItem.DropDownItems.AddRange(new ToolStripItem[] { aboutToolStripMenuItem });
+            helpToolStripMenuItem.Name = "helpToolStripMenuItem";
+            helpToolStripMenuItem.Size = new Size(55, 24);
+            helpToolStripMenuItem.Text = "Help";
+            // 
+            // aboutToolStripMenuItem
+            // 
+            aboutToolStripMenuItem.Name = "aboutToolStripMenuItem";
+            aboutToolStripMenuItem.Size = new Size(224, 26);
+            aboutToolStripMenuItem.Text = "About";
+            aboutToolStripMenuItem.Click += aboutToolStripMenuItem_Click;
+            // 
             // ParsonsForm1
             // 
-            AutoScaleDimensions = new SizeF(10F, 25F);
+            AutoScaleDimensions = new SizeF(8F, 20F);
             AutoScaleMode = AutoScaleMode.Font;
-            ClientSize = new Size(791, 622);
+            ClientSize = new Size(633, 498);
             Controls.Add(menuStrip1);
             MainMenuStrip = menuStrip1;
-            Margin = new Padding(4);
             Name = "ParsonsForm1";
             Text = "Form1";
             FormClosing += ParsonsForm1_FormClosing;
@@ -186,5 +209,8 @@
         private ToolStripMenuItem vRAMViewerToolStripMenuItem;
         private ToolStripMenuItem saveStateToolStripMenuItem;
         private ToolStripMenuItem loadStateToolStripMenuItem;
+        private ToolStripMenuItem turboModeToolStripMenuItem;
+        private ToolStripMenuItem masterSystemToolStripMenuItem;
+        private ToolStripMenuItem gameGearToolStripMenuItem;
     }
 }

Desktop/Form1.cs

@@ -18,14 +18,14 @@ namespace Desktop
         private Bitmap _screenBitmap = new Bitmap(256, 192, PixelFormat.Format32bppArgb);
         private NAudioPlayer _audioPlayer;
         private Task _emulatorTask;
-        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;
         private string _currentRomName = "No ROM";
         private string _currentRomPath = "";
-        private Stopwatch _stopwatch = new System.Diagnostics.Stopwatch();
+        private Stopwatch _stopwatch = new Stopwatch();
+        private string _romType = "TBC";
+        private bool isTurboMode = false;
         public bool IsRunning { get; private set; } = false;
 
         public ushort? Breakpoint
@@ -34,88 +34,127 @@ namespace Desktop
             set { if (_machine != null) _machine.Breakpoint = value; }
         }
 
+#pragma warning disable CS8618 // Non-nullable field must contain a non-null value when exiting constructor. Consider adding the 'required' modifier or declaring as nullable.
         public ParsonsForm1()
+#pragma warning restore CS8618 // Non-nullable field must contain a non-null value when exiting constructor. Consider adding the 'required' modifier or declaring as nullable.
         {
             InitializeComponent();
-
-            // These are perfectly safe for the Visual Studio Designer!
             this.KeyPreview = true;
+#pragma warning disable CS8622 // Nullability of reference types in type of parameter doesn't match the target delegate (possibly because of nullability attributes).
             this.KeyDown += Form1_KeyDown;
+#pragma warning restore CS8622 // Nullability of reference types in type of parameter doesn't match the target delegate (possibly because of nullability attributes).
+#pragma warning disable CS8622 // Nullability of reference types in type of parameter doesn't match the target delegate (possibly because of nullability attributes).
             this.KeyUp += Form1_KeyUp;
+#pragma warning restore CS8622 // Nullability of reference types in type of parameter doesn't match the target delegate (possibly because of nullability attributes).
             this.DoubleBuffered = true;
             this.ResizeRedraw = true;
         }
-
-        // The Designer ignores this completely, but the compiled game runs it instantly!
         protected override void OnLoad(EventArgs e)
         {
             base.OnLoad(e);
 
-            this.Text = $"Parsons Master System - {_currentRomName}";
+            this.Text = $"{_romType} Parsons Master System 2026 - {_currentRomName}";
 
-            // Safe to initialize hardware and files here!
+            this.BackColor = Color.Black;
             _machine = new SmsMachine();
             _audioPlayer = new NAudioPlayer();
             _machine.AudioProcessor.AudioDevice = _audioPlayer;
+            IsRunning = false;
 
             PopulateIncludedRomsMenu();
         }
 
-        private void DrawScreen()
+        private void DrawScreen(int[] safeFrame)
         {
-            // Rapidly copy our VDP FrameBuffer into the Windows Bitmap
+            // Rapidly the Frame into the Windows Bitmap
             var data = _screenBitmap.LockBits(new Rectangle(0, 0, 256, 192), ImageLockMode.WriteOnly, PixelFormat.Format32bppArgb);
-            Marshal.Copy(_machine.VideoProcessor.FrameBuffer, 0, data.Scan0, _machine.VideoProcessor.FrameBuffer.Length);
+
+            //Frame buffer draw
+            Marshal.Copy(safeFrame, 0, data.Scan0, safeFrame.Length);
+
+            //Direct VDP draw
+            //Marshal.Copy(_machine.VideoProcessor.FrameBuffer, 0, data.Scan0, _machine.VideoProcessor.FrameBuffer.Length);
+
             _screenBitmap.UnlockBits(data);
             this.Invalidate();
             TotalFrameCount++;
         }
+
         protected override void OnPaint(PaintEventArgs e)
         {
-            // Always call the base method so Windows can draw your MenuStrip!
             base.OnPaint(e);
 
-            // THE FIX: We MUST ensure the designer has actually built the menu strip before asking for its height!
             if (_screenBitmap != null && menuStrip1 != null)
             {
-                // 1. Set the rendering mode for perfect, chunky retro pixels!
+                // 1. Maintain perfect, chunky retro pixels
                 e.Graphics.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.NearestNeighbor;
                 e.Graphics.PixelOffsetMode = System.Drawing.Drawing2D.PixelOffsetMode.Half;
 
-                // 2. Calculate the drawing area. 
-                // We start drawing BELOW the MenuStrip so it doesn't get covered up.
                 int topOffset = menuStrip1.Height;
-                Rectangle renderArea = new Rectangle(
-                    0,
-                    topOffset,
-                    this.ClientSize.Width,
-                    this.ClientSize.Height - topOffset
-                );
+                int availableWidth = this.ClientSize.Width;
+                int availableHeight = this.ClientSize.Height - topOffset;
 
-                // 3. Blast the bitmap directly onto the graphics card buffer!
-                e.Graphics.DrawImage(_screenBitmap, renderArea);
+                // 2. THE LENS LENS: Determine what part of the VDP buffer we actually want to show!
+                // (Safely check if the machine/video processor exists yet)
+                bool isGG = _machine?.VideoProcessor?.IsGameGear ?? false;
+
+                int sourceWidth = isGG ? 160 : 256;
+                int sourceHeight = isGG ? 144 : 192;
+                int sourceX = isGG ? 48 : 0; // Skip 48 pixels in!
+                int sourceY = isGG ? 24 : 0; // Skip 24 pixels down!
+
+                // Create a rectangle defining the specific pixels to extract from the raw frame buffer
+                Rectangle sourceRect = new Rectangle(sourceX, sourceY, sourceWidth, sourceHeight);
+
+                // 3. Calculate the maximum scale factor for the cropped image
+                float scaleX = (float)availableWidth / sourceWidth;
+                float scaleY = (float)availableHeight / sourceHeight;
+
+                // Pick the smaller scale so the image never bleeds off the edge
+                float scale = Math.Min(scaleX, scaleY);
+
+                // 4. Calculate the new physical pixel dimensions
+                int newWidth = (int)(sourceWidth * scale);
+                int newHeight = (int)(sourceHeight * scale);
+
+                // 5. Center the image (Letterboxing / Pillarboxing)
+                int offsetX = (availableWidth - newWidth) / 2;
+                int offsetY = topOffset + ((availableHeight - newHeight) / 2);
+
+                // Create a rectangle defining exactly where on the Windows form to draw the extracted pixels
+                Rectangle destRect = new Rectangle(offsetX, offsetY, newWidth, newHeight);
+
+                // 6. Blast the perfectly cropped and scaled bitmap onto the screen!
+                e.Graphics.DrawImage(_screenBitmap, destRect, sourceRect, GraphicsUnit.Pixel);
             }
         }
 
+
         public void StartEmulator()
         {
             if (IsRunning) return;
             IsRunning = true;
             TotalFrameCount = 0;
-
-            double TargetFrameTime = 1000.0 / 59.92274;
-
             _emulatorTask = Task.Run(() =>
             {
+                double targetFps = 59.94;
+                double TargetFrameTime = 1000.0 / targetFps;
                 _stopwatch.Restart();
 
                 double nextFrameTargetTime = _stopwatch.Elapsed.TotalMilliseconds + TargetFrameTime;
                 double lastFpsUpdate = _stopwatch.Elapsed.TotalMilliseconds;
                 int framesThisSecond = 0;
-
+                try
+                {
                     while (IsRunning)
                     {
-                    // Mark exactly when the emulator starts thinking
+                        //targetFps = isTurboMode ? 1000 : 59.94;
+                        //TargetFrameTime = 1000.0 / targetFps;
+                        BeginInvoke((System.Windows.Forms.MethodInvoker)delegate
+                        {
+                            targetFps = isTurboMode ? 1000 : 59.94;
+                            TargetFrameTime = 1000.0 / targetFps;
+                        });
                         double frameStartTime = _stopwatch.Elapsed.TotalMilliseconds;
 
                         // --- POLL PHYSICAL CONTROLLER ---
@@ -137,14 +176,18 @@ namespace Desktop
                         // --------------------------------
                         _machine.RunFrame();
 
+                        int[] frozenFrame = (int[])_machine.VideoProcessor.FrameBuffer.Clone();
+
                         // 2. FIRE AND FORGET! Tell Windows to draw, but DO NOT WAIT for it to finish!
-                    BeginInvoke((System.Windows.Forms.MethodInvoker)delegate { DrawScreen(); });
+                        BeginInvoke((System.Windows.Forms.MethodInvoker)delegate { DrawScreen(frozenFrame); });
 
                         // 3. Safety catch
                         if (_machine.Breakpoint.HasValue && _machine.Cpu.PC == _machine.Breakpoint.Value)
                         {
                             IsRunning = false;
+#pragma warning disable CS8625 // Cannot convert null literal to non-nullable reference type.
                             BeginInvoke((System.Windows.Forms.MethodInvoker)delegate { _debugger?.uiUpdateTimer_Tick(null, EventArgs.Empty); });
+#pragma warning restore CS8625 // Cannot convert null literal to non-nullable reference type.
                             break;
                         }
 
@@ -176,7 +219,7 @@ namespace Desktop
 
                             BeginInvoke((System.Windows.Forms.MethodInvoker)delegate
                             {
-                            this.Text = $"Parsons Master System 2026 - {_currentRomName} [FPS/FT: {FramesPerSecond:F0}/{FrameTime:F1}]";
+                                this.Text = $"{_romType} Parsons Master System 2026 - {_currentRomName} [FPS: {FramesPerSecond:F0}]";
                             });
                         }
 
@@ -187,6 +230,23 @@ namespace Desktop
                             nextFrameTargetTime = currentTime + TargetFrameTime;
                         }
                     }
+                }
+                catch (Exception ex)
+                {
+                    IsRunning = false;
+
+                    this.Invoke((System.Windows.Forms.MethodInvoker)delegate
+                    {
+                        MessageBox.Show(
+                            $"The Z80 CPU Panicked!\n\n" +
+                            $"PC Address: 0x{_machine.Cpu.PC:X4}\n" +
+                            $"Error: {ex.Message}\n\n" +
+                            $"Stack Trace:\n{ex.StackTrace}",
+                            "Fatal Emulator Crash",
+                            MessageBoxButtons.OK,
+                            MessageBoxIcon.Error);
+                    });
+                }
             });
         }
 
@@ -194,7 +254,8 @@ namespace Desktop
         {
             IsRunning = false;
         }
-        private async void LoadRomAndStart(string filePath)
+
+        private async void LoadRomDataAndStart(byte[] romData, string fileName, string uniqueId)
         {
             StopEmulator();
             if (_emulatorTask != null)
@@ -202,35 +263,49 @@ namespace Desktop
                 await _emulatorTask;
             }
 
-            // 1. SAVE THE PREVIOUS GAME!
             SaveCurrentSram();
 
-            // 2. Load the file
-            byte[] rom = File.ReadAllBytes(filePath);
+            // Blast the bytes straight into the virtual cartridge slot!
+            _machine.LoadCartridge(romData);
 
-            // 3. Jam it into the Sega Mapper
-            _machine.LoadCartridge(rom);
+            // Check the hardware mode based on the file name
+            bool isGG = fileName.EndsWith(".gg", StringComparison.OrdinalIgnoreCase);
+            _machine.VideoProcessor.IsGameGear = isGG;
 
-            // 4. Update the path tracking
-            _currentRomPath = filePath;
-            _currentRomName = Path.GetFileNameWithoutExtension(filePath);
-            this.Text = $"Parsons Master System - {_currentRomName}";
+            // We use uniqueId to track the SRAM file path (works for both real paths and resource names)
+            _currentRomPath = uniqueId;
+            _currentRomName = Path.GetFileNameWithoutExtension(fileName);
+
+            // Update the window title dynamically
+            _romType = isGG ? "GG" : "MS";
+            this.Text = $"{_romType} Parsons Master System 2026 - {_currentRomName}";
 
-            // 5. LOAD THE NEW SAVE DATA FROM THE EXE FOLDER!
             string savPath = GetSaveFilePath();
             if (savPath != null)
             {
                 _machine.MemoryBus.LoadSaveData(savPath);
             }
 
-            // 6. Turn the power on!
             StartEmulator();
         }
+
+        private void LoadRomAndStart(string filePath)
+        {
+            if (!File.Exists(filePath)) return;
+
+            // Read from the hard drive, then pass to the universal loader
+            byte[] romData = File.ReadAllBytes(filePath);
+            LoadRomDataAndStart(romData, Path.GetFileName(filePath), filePath);
+        }
+
+        
         private string GetSaveFilePath()
         {
             // Don't try to save if a game hasn't been loaded yet!
             if (string.IsNullOrEmpty(_currentRomName) || _currentRomName == "No ROM")
+#pragma warning disable CS8603 // Possible null reference return.
                 return null;
+#pragma warning restore CS8603 // Possible null reference return.
 
             // Application.StartupPath is the exact folder containing your .exe
             string exeFolder = Application.StartupPath;
@@ -252,34 +327,87 @@ namespace Desktop
 
         private void PopulateIncludedRomsMenu()
         {
-            // The folder you used for Golden Axe Warrior
-            string romsDirectory = @"C:\Parsons\Local Code Projects\ParsonsMasterSystem2026\Desktop\ROMS\";
+            string romsDirectory = "Desktop.ROMS";
+            string[] files = GetFilesInResourceDirectory(romsDirectory);
 
-            if (Directory.Exists(romsDirectory))
+            foreach (string resourceName in files)
             {
-                string[] romFiles = Directory.GetFiles(romsDirectory, "*.sms");
+                // 1. Strip the "Desktop.ROMS." prefix
+                string cleanFileName = resourceName.Replace("Desktop.ROMS.", "");
 
-                foreach (string file in romFiles)
+                // 2. Strip the extension for a beautiful menu item (e.g. "Sonic")
+                string menuName = Path.GetFileNameWithoutExtension(cleanFileName);
+
+                ToolStripMenuItem romMenuItem = new ToolStripMenuItem(menuName);
+
+                // 3. Point the click event to our new extraction helper!
+                romMenuItem.Click += (sender, e) => LoadEmbeddedRom(resourceName);
+
+                // 4. Sort into the correct menu based on extension!
+                if (resourceName.EndsWith(".gg", StringComparison.OrdinalIgnoreCase))
                 {
-                    // Create a new dropdown item for each .sms file it finds
-                    string romName = Path.GetFileNameWithoutExtension(file);
-                    ToolStripMenuItem romMenuItem = new ToolStripMenuItem(romName);
-
-                    // When clicked, pass the file path to our helper method
-                    romMenuItem.Click += (sender, e) => LoadRomAndStart(file);
-
-                    // Add it to the "Included" submenu (make sure the name matches your designer element!)
-                    includedToolStripMenuItem.DropDownItems.Add(romMenuItem);
+                    gameGearToolStripMenuItem.DropDownItems.Add(romMenuItem);
+                }
+                else if (resourceName.EndsWith(".sms", StringComparison.OrdinalIgnoreCase))
+                {
+                    masterSystemToolStripMenuItem.DropDownItems.Add(romMenuItem);
                 }
             }
         }
 
+        private void LoadEmbeddedRom(string resourceName)
+        {
+            // 1. Strip off the ugly prefix to get the real file name for the UI and the .gg check
+            string cleanFileName = resourceName.Replace("Desktop.ROMS.", "");
+
+            Assembly assembly = Assembly.GetExecutingAssembly();
+
+            // 2. Open a direct pipe to the internal resource
+            using (Stream stream = assembly.GetManifestResourceStream(resourceName))
+            {
+                if (stream == null) return;
+
+                // 3. Copy the stream entirely in RAM—never touching the hard drive!
+                using (MemoryStream ms = new MemoryStream())
+                {
+                    stream.CopyTo(ms);
+                    byte[] romData = ms.ToArray();
+
+                    // 4. Pass the raw bytes to our universal loader
+                    LoadRomDataAndStart(romData, cleanFileName, resourceName);
+                }
+            }
+        }
+
+        public static string[] GetFilesInResourceDirectory(string directoryPrefix)
+        {
+            // Get the assembly containing the embedded resources. 
+            // Change this if your resources are in a different project/assembly.
+            Assembly assembly = Assembly.GetExecutingAssembly();
+
+            // Ensure the prefix ends with a dot so we don't accidentally match 
+            // similarly named folders (e.g., matching "Folder" but not "FolderTwo")
+            if (!directoryPrefix.EndsWith("."))
+            {
+                directoryPrefix += ".";
+            }
+
+            // Get all resource names and filter by our "directory" prefix
+            string[] allResources = assembly.GetManifestResourceNames();
+
+            string[] filesInDirectory = allResources
+                .Where(resource => resource.StartsWith(directoryPrefix, StringComparison.OrdinalIgnoreCase))
+                .ToArray();
+
+            return filesInDirectory;
+        }
+
         private void selectROMToolStripMenuItem_Click(object sender, EventArgs e)
         {
             using (OpenFileDialog ofd = new OpenFileDialog())
             {
                 ofd.Title = "Select Master System ROM";
-                ofd.Filter = "SMS ROMs (*.sms)|*.sms|All Files (*.*)|*.*";
+                ofd.Filter = "SMS ROMs (*.sms)|*.sms|GG ROMs (*.gg)|*.gg|All Files (*.*)|*.*";
 
                 if (ofd.ShowDialog() == DialogResult.OK)
                 {
@@ -313,10 +441,6 @@ namespace Desktop
             _vramViewer.Show();
         }
 
-        private void includedToolStripMenuItem_Click(object sender, EventArgs e)
-        {
-
-        }
 
         private void exitToolStripMenuItem_Click(object sender, EventArgs e)
         {
@@ -400,5 +524,34 @@ namespace Desktop
             // 3. Resume
             StartEmulator();
         }
+
+        private void turboModeToolStripMenuItem_Click(object sender, EventArgs e)
+        {
+            turboModeToolStripMenuItem.Checked = !turboModeToolStripMenuItem.Checked;
+            isTurboMode = turboModeToolStripMenuItem.Checked ? true : false;
+        }
+
+        private void aboutToolStripMenuItem_Click(object sender, EventArgs e)
+        {
+            MessageBox.Show(
+                            $"First full release of Parsons Master System Emulator 2026!\r\n\r\nFeatures (v1.0):\r\n\r\n" +
+                            $"    *Full compatibility with all Master System and Game Gear ROMs\r\n" +
+                            $"    *Full window scaling with fixed aspect ratio (SMS & GG)\r\n" +
+                            $"    *Full 4 channel SN76489 implememtation using NAudio\r\n" +
+                            $"    *SRAM auto save and load (Battery Backed RAM)\r\n" +
+                            $"    *Keyboard and XInput control pad support\r\n" +
+                            $"    *Comprehensive Debugger\r\n" +
+                            $"    *VRAM Viewer\r\n" +
+                            $"    *Single point Save State\r\n" +
+                            $"    *Turbo mode\r\n" +
+                            $"    *Includes a selection of commercial ROMs\r\n\r\n" +
+                            $"Planned updates (v1.1):\r\n\r\n" +
+                            $"    *Architectural double buffering (prevent screen tear)\r\n" +
+                            $"    *Graphics shaders (scanlines etc...)\r\n" +
+                            $"    *Add multiple Save States per game\r\n\r\n\r\n" +
+                            $"(c) Marc Parsons 2026","Parsons Master System 2026 v1.0",
+                            MessageBoxButtons.OK,
+                            MessageBoxIcon.Information);
+        }
     }
 }

Desktop/VramViewerForm.cs

@@ -45,7 +45,6 @@ namespace Desktop
                 int tileX = (tile % 32) * 8;
                 int tileY = (tile / 32) * 8;
                 int tileAddress = tile * 32;
-
                 // Decode the 8x8 pixels
                 for (int y = 0; y < 8; y++)
                 {
@@ -57,19 +56,19 @@ namespace Desktop
                     for (int x = 0; x < 8; x++)
                     {
                         int shift = 7 - x;
-                        int colorIndex = ((bp0 >> shift) & 1) | (((bp1 >> shift) & 1) << 1) |
+                        int colourIndex = ((bp0 >> shift) & 1) | (((bp1 >> shift) & 1) << 1) |
                                          (((bp2 >> shift) & 1) << 2) | (((bp3 >> shift) & 1) << 3);
 
                         // Use the Sprite Palette (Offset 16) so characters and enemies are colored correctly
-                        byte smsColor = _vdp.CRAM[16 + colorIndex];
-                        int r = (smsColor & 0x03) * 85;
-                        int g = ((smsColor >> 2) & 0x03) * 85;
-                        int b = ((smsColor >> 4) & 0x03) * 85;
+                        int colour = _vdp.GetRgbColour(16, colourIndex);
+                        //int r = (smsColor & 0x03) * 85;
+                        //int g = ((smsColor >> 2) & 0x03) * 85;
+                        //int b = ((smsColor >> 4) & 0x03) * 85;
 
                         // Background color (Index 0) is technically transparent for sprites, so we render it as magenta
-                        if (colorIndex == 0) { r = 255; g = 0; b = 255; }
+                        //if (colourIndex == 0) { int r = 255; int g = 0; int b = 255; }
 
-                        _pixelData[((tileY + y) * 256) + (tileX + x)] = (255 << 24) | (r << 16) | (g << 8) | b;
+                        _pixelData[((tileY + y) * 256) + (tileX + x)] = colourIndex == 0 ? (255 << 24) | (255 << 16) | (0 << 8) | 255 : colour;
                     }
                 }
             }

Parsons.Steamdeck/Parsons.Steamdeck.csproj

@@ -0,0 +1,22 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+	<PropertyGroup>
+		<OutputType>Exe</OutputType>
+		<TargetFramework>net8.0</TargetFramework>
+		<ImplicitUsings>enable</ImplicitUsings>
+		<Nullable>enable</Nullable>
+
+		<AllowUnsafeBlocks>true</AllowUnsafeBlocks>
+		<PublishAot>true</PublishAot>
+		<OptimizationPreference>Size</OptimizationPreference>
+	</PropertyGroup>
+
+	<ItemGroup>
+	  <PackageReference Include="Raylib-cs" Version="8.0.0" />
+	</ItemGroup>
+
+	<ItemGroup>
+	  <ProjectReference Include="..\Core\Core.csproj" />
+	</ItemGroup>
+
+</Project>

Parsons.Steamdeck/Program.cs

@@ -0,0 +1,125 @@
+using System;
+using System.IO;
+using System.Numerics;
+using Core;
+using Raylib_cs;
+
+namespace Parsons.SteamDeck
+{
+    class Program
+    {
+        static void Main(string[] args)
+        {
+            // 1. Initialize Cross-Platform OpenGL Window
+            // THE FIX: Use PascalCase C# enums
+            Raylib.SetConfigFlags(ConfigFlags.ResizableWindow);
+            Raylib.InitWindow(1280, 800, "Parsons Master System"); // Native Steam Deck Resolution
+            Raylib.InitAudioDevice();
+
+            // 2. Initialize Hardware-Agnostic Audio Stream (44.1kHz, 32-bit float, Mono)
+            AudioStream audioStream = Raylib.LoadAudioStream(44100, 32, 1);
+            Raylib.PlayAudioStream(audioStream);
+
+            // 3. Boot the Core Emulator
+            SmsMachine machine = new SmsMachine();
+            RaylibAudioPlayer audioPlayer = new RaylibAudioPlayer();
+            machine.AudioProcessor.AudioDevice = audioPlayer;
+
+            // Load a ROM (Passed via command line argument, e.g. ./Parsons.SteamDeck sonic.sms)
+            if (args.Length > 0 && File.Exists(args[0]))
+            {
+                machine.LoadCartridge(File.ReadAllBytes(args[0]));
+                bool isGG = args[0].EndsWith(".gg", StringComparison.OrdinalIgnoreCase);
+                machine.VideoProcessor.IsGameGear = isGG;
+            }
+
+            // Lock the engine loop to 60 FPS natively
+            Raylib.SetTargetFPS(60);
+
+            // 4. Prepare the Video Texture Pipeline
+            // THE FIX: Use Color.Black
+            Image img = Raylib.GenImageColor(256, 192, Color.Black);
+            Texture2D vdpTexture = Raylib.LoadTextureFromImage(img);
+            byte[] pixelBuffer = new byte[256 * 192 * 4]; // Fast RGBA translation array
+
+            // --- THE MAIN GAME LOOP ---
+            while (!Raylib.WindowShouldClose())
+            {
+                // A. OS-Agnostic Input Polling (Works on Keyboard AND Steam Deck Controller)
+                // THE FIX: PascalCase KeyboardKey and GamepadButton enums
+                byte pad = 0xFF;
+                if (Raylib.IsKeyDown(KeyboardKey.Up) || Raylib.IsGamepadButtonDown(0, GamepadButton.LeftFaceUp)) pad &= 0xFE;
+                if (Raylib.IsKeyDown(KeyboardKey.Down) || Raylib.IsGamepadButtonDown(0, GamepadButton.LeftFaceDown)) pad &= 0xFD;
+                if (Raylib.IsKeyDown(KeyboardKey.Left) || Raylib.IsGamepadButtonDown(0, GamepadButton.LeftFaceLeft)) pad &= 0xFB;
+                if (Raylib.IsKeyDown(KeyboardKey.Right) || Raylib.IsGamepadButtonDown(0, GamepadButton.LeftFaceRight)) pad &= 0xF7;
+
+                // Steam Deck "A" Button is RightFaceDown. "B" Button is RightFaceRight.
+                if (Raylib.IsKeyDown(KeyboardKey.Z) || Raylib.IsGamepadButtonDown(0, GamepadButton.RightFaceDown)) pad &= 0xEF; // B1 / A Button
+                if (Raylib.IsKeyDown(KeyboardKey.X) || Raylib.IsGamepadButtonDown(0, GamepadButton.RightFaceRight)) pad &= 0xDF; // B2 / B Button
+
+                machine.IoBus.Joypad1Keyboard = pad;
+
+                // B. Execute exactly one frame of T-States
+                machine.RunFrame();
+
+                // C. Flush Audio Buffer to the Sound Card
+                if (Raylib.IsAudioStreamProcessed(audioStream))
+                {
+                    float[] samples = audioPlayer.GetQueuedSamples();
+                    if (samples.Length > 0)
+                    {
+                        unsafe
+                        {
+                            fixed (float* p = samples)
+                            {
+                                Raylib.UpdateAudioStream(audioStream, p, samples.Length);
+                            }
+                        }
+                    }
+                }
+
+                // D. Fast Pixel Translation (ARGB int -> RGBA bytes)
+                int[] frameBuffer = machine.VideoProcessor.FrameBuffer;
+                for (int i = 0; i < frameBuffer.Length; i++)
+                {
+                    int argb = frameBuffer[i];
+                    pixelBuffer[i * 4 + 0] = (byte)((argb >> 16) & 0xFF); // R
+                    pixelBuffer[i * 4 + 1] = (byte)((argb >> 8) & 0xFF);  // G
+                    pixelBuffer[i * 4 + 2] = (byte)(argb & 0xFF);         // B
+                    pixelBuffer[i * 4 + 3] = 255;                         // A
+                }
+
+                // Push bytes directly to the GPU Texture
+                unsafe
+                {
+                    fixed (byte* p = pixelBuffer)
+                    {
+                        Raylib.UpdateTexture(vdpTexture, p);
+                    }
+                }
+
+                // E. Render to Screen (Perfect Aspect Ratio Scaling)
+                Raylib.BeginDrawing();
+                Raylib.ClearBackground(Color.Black);
+
+                float scale = Math.Min((float)Raylib.GetScreenWidth() / 256, (float)Raylib.GetScreenHeight() / 192);
+                Rectangle sourceRec = new Rectangle(0, 0, 256, 192);
+                Rectangle destRec = new Rectangle(
+                    (Raylib.GetScreenWidth() - (256 * scale)) * 0.5f,
+                    (Raylib.GetScreenHeight() - (192 * scale)) * 0.5f,
+                    256 * scale, 192 * scale);
+
+                // Draw the VDP Frame
+                Raylib.DrawTexturePro(vdpTexture, sourceRec, destRec, new Vector2(0, 0), 0.0f, Color.White);
+
+                Raylib.EndDrawing();
+            }
+
+            // Clean up hardware resources on exit
+            Raylib.UnloadTexture(vdpTexture);
+            Raylib.UnloadAudioStream(audioStream);
+            Raylib.CloseAudioDevice();
+            Raylib.CloseWindow();
+        }
+    }
+}

Parsons.Steamdeck/RaylibAudioPlayer.cs

@@ -0,0 +1,28 @@
+using Core.Interfaces;
+using System.Collections.Concurrent;
+
+namespace Parsons.SteamDeck
+{
+    public class RaylibAudioPlayer : IAudioDevice
+    {
+        private ConcurrentQueue<float> _sampleQueue = new ConcurrentQueue<float>();
+
+        public void AddSample(float sample)
+        {
+            // Queue the sample from the emulator core
+            _sampleQueue.Enqueue(sample);
+        }
+
+        public float[] GetQueuedSamples()
+        {
+            // Pull all pending samples out of the queue to send to the sound card
+            int count = _sampleQueue.Count;
+            float[] buffer = new float[count];
+            for (int i = 0; i < count; i++)
+            {
+                _sampleQueue.TryDequeue(out buffer[i]);
+            }
+            return buffer;
+        }
+    }
+}

ParsonsMasterSystem2026.sln

@@ -1,12 +1,14 @@
 
 Microsoft Visual Studio Solution File, Format Version 12.00
 # Visual Studio Version 17
-VisualStudioVersion = 17.14.37216.2 d17.14
+VisualStudioVersion = 17.14.37216.2
 MinimumVisualStudioVersion = 10.0.40219.1
 Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Desktop", "Desktop\Desktop.csproj", "{E245F3A5-E541-43BB-B64E-B4B2BB3D8C51}"
 EndProject
 Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Core", "Core\Core.csproj", "{B0A741E4-CE3E-4DF0-96B2-E314973F9201}"
 EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Parsons.Steamdeck", "Parsons.Steamdeck\Parsons.Steamdeck.csproj", "{B619DF68-7EBF-4C6A-AC24-AD5250404943}"
+EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
 		Debug|Any CPU = Debug|Any CPU
@@ -21,6 +23,10 @@ Global
 		{B0A741E4-CE3E-4DF0-96B2-E314973F9201}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{B0A741E4-CE3E-4DF0-96B2-E314973F9201}.Release|Any CPU.ActiveCfg = Release|Any CPU
 		{B0A741E4-CE3E-4DF0-96B2-E314973F9201}.Release|Any CPU.Build.0 = Release|Any CPU
+		{B619DF68-7EBF-4C6A-AC24-AD5250404943}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{B619DF68-7EBF-4C6A-AC24-AD5250404943}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{B619DF68-7EBF-4C6A-AC24-AD5250404943}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{B619DF68-7EBF-4C6A-AC24-AD5250404943}.Release|Any CPU.Build.0 = Release|Any CPU
 	EndGlobalSection
 	GlobalSection(SolutionProperties) = preSolution
 		HideSolutionNode = FALSE