Got main system and VDP working! There is a display!

Core/Cpu/Z80.cs

@@ -1275,6 +1275,18 @@ namespace Core.Cpu
 
             switch (extendedOpcode)
             {
+                case 0x41: // OUT (C), B
+                    _simpleIoBus.WritePort(BC.Word, BC.High);
+                    return 12;
+                case 0x49: // OUT (C), C
+                    _simpleIoBus.WritePort(BC.Word, BC.Low);
+                    return 12;
+                case 0x61: // OUT (C), H
+                    _simpleIoBus.WritePort(BC.Word, HL.High);
+                    return 12;
+                case 0x69: // OUT (C), L
+                    _simpleIoBus.WritePort(BC.Word, HL.Low);
+                    return 12;
                 case 0x43: // LD (nn), BC
                     ushort dest43 = FetchWord();
                     WriteMemory(dest43, BC.Low);
@@ -1494,6 +1506,48 @@ namespace Core.Cpu
                         if ((n & 0x02) != 0) AF.Low |= 0x20; // Bit 5 from bit 1
                         return 16;
                     }
+                case 0xA3: // OUTI
+                    {
+                        // 1. Read data from memory at HL
+                        byte valA3 = ReadMemory(HL.Word);
+
+                        // 2. Decrement the B register
+                        BC.High--;
+
+                        // 3. Output the data to the port specified by C
+                        _simpleIoBus.WritePort(BC.Word, valA3);
+
+                        // 4. Increment the memory pointer
+                        HL.Word++;
+
+                        // 5. Update Flags (N is always set. Z is set if B reached 0)
+                        AF.Low |= 0x02;
+                        if (BC.High == 0) AF.Low |= 0x40;
+                        else AF.Low &= 0xBF;
+
+                        return 16;
+                    }
+                case 0xB3: // OTIR
+                    {
+                        // This does exactly the same thing as OUTI, but loops until B == 0
+                        byte valB3 = ReadMemory(HL.Word);
+                        BC.High--;
+                        _simpleIoBus.WritePort(BC.Word, valB3);
+                        HL.Word++;
+
+                        AF.Low |= 0x02;
+                        if (BC.High != 0)
+                        {
+                            AF.Low &= 0xBF; // Z is reset
+                            PC -= 2;        // Loop back and execute ED B3 again!
+                            return 21;
+                        }
+                        else
+                        {
+                            AF.Low |= 0x40; // Z is set
+                            return 16;
+                        }
+                    }
                 case 0xB0: // LDIR
                     {
                         byte val00 = ReadMemory(HL.Word);

Core/Io/SmsIoBus.cs

@@ -1,11 +1,11 @@
 using Core.Interfaces;
+using Core.Video;
 
 namespace Core.Io
 {
     public class SmsIoBus : IIoBus
     {
-        // We will wire these up in the next phases!
+        public SmsVdp VideoProcessor { get; set; }
-        // public Vdp VideoProcessor { get; set; }
         // public Psg AudioProcessor { get; set; }
 
         // Joypad State (0xFF means no buttons pressed - the SMS uses Active-Low logic!)
@@ -18,11 +18,17 @@ namespace Core.Io
             // hardware only physically wires up the bottom 8 bits.
             byte lowerPort = (byte)(port & 0xFF);
 
+            if (lowerPort == 0x7E)
+            {
+                // VDP V-Counter (Vertical Scanline Position)
+                return VideoProcessor.ReadVCounter();
+            }
+
             if (lowerPort >= 0x80 && lowerPort <= 0xBF)
             {
-                // VDP Read (Usually 0xBE for VRAM Data, 0xBF for Status Flags)
+                // Even ports (like 0xBE) are Data. Odd ports (like 0xBF) are Control.
-                // return VideoProcessor.ReadPort(lowerPort);
+                if ((lowerPort & 0x01) == 0) return VideoProcessor.ReadDataPort();
-                return 0x00;
+                else return VideoProcessor.ReadControlPort();
             }
             if (lowerPort == 0xDC)
             {
@@ -49,8 +55,8 @@ namespace Core.Io
             }
             else if (lowerPort >= 0x80 && lowerPort <= 0xBF)
             {
-                // VDP Write (Usually 0xBE for VRAM Data, 0xBF for Control Registers)
+                if ((lowerPort & 0x01) == 0) VideoProcessor.WriteDataPort(value);
-                // VideoProcessor.WritePort(lowerPort, value);
+                else VideoProcessor.WriteControlPort(value);
             }
             else if (lowerPort <= 0x3F)
             {

Core/SmsMachine.cs

@@ -1,6 +1,9 @@
 using Core.Cpu;
 using Core.Io;
 using Core.Memory;
+using System;
+using System.IO;
+using System.Collections.Generic;
 
 namespace Core
 {
@@ -9,18 +12,17 @@ namespace Core
         public Z80 Cpu { get; private set; }
         public SmsMemoryBus MemoryBus { get; private set; }
         public SmsIoBus IoBus { get; private set; }
+        public Core.Video.SmsVdp VideoProcessor { get; private set; }
         public ushort? Breakpoint { get; set; } = null;
 
         // NTSC SMS T-States per frame
         public const int TStatesPerFrame = 59736;
-        public long TotalFrameCount { get; private set; } = 0;
-        public double FramesPerSecond { get; private set; } = 0;
-        public double FrameTime { get; private set; } = 0;
 
         public SmsMachine()
         {
             MemoryBus = new SmsMemoryBus();
-            IoBus = new SmsIoBus();
+            VideoProcessor = new Core.Video.SmsVdp();
+            IoBus = new SmsIoBus { VideoProcessor = this.VideoProcessor };
             Cpu = new Z80(MemoryBus, IoBus);
         }
 
@@ -34,8 +36,23 @@ namespace Core
         {
             MemoryBus.CleanRAMData();
             Cpu.Reset();
+        }
 
-            // We will reset the VDP and PSG here later!
+        public int StepMachine()
+        {
+            // 1. Tick the CPU
+            int tStates = Cpu.Step();
+
+            // 2. Tell the VDP how much time just passed
+            VideoProcessor.Update(tStates);
+
+            // 3. Trigger interrupts if the VDP hit scanline 192
+            if (VideoProcessor.InterruptPending)
+            {
+                tStates += Cpu.RequestInterrupt();
+            }
+
+            return tStates;
         }
 
         public void RunFrame()
@@ -44,18 +61,51 @@ namespace Core
 
             while (currentFrameTStates < TStatesPerFrame)
             {
-                int tStates = Cpu.Step();
+                currentFrameTStates += StepMachine();
-                currentFrameTStates += tStates;
+                string filePath = "captured_data.txt";
 
-                // --- FUTURE EXPANSION ---
+                // Mock data to loop through
-                // VideoProcessor.Update(tStates);
+                //List<ushort> sensorReadings = new List<ushort> { Cpu.PC, Cpu.AF.Word, Cpu.BC.Word, Cpu.DE.Word, Cpu.HL.Word, Cpu.SP};
-                // AudioProcessor.Update(tStates);
+                //List<string> type = new List<string> {"PC: 0x", "AF: 0x", "BC: 0x", "DE: 0x", "HL: 0x", "SP: 0x" };
 
-                // if (VideoProcessor.IsVBlanking && VideoProcessor.InterruptsEnabled)
+                //try
-                // {
+                //{
-                //     Cpu.RequestInterrupt();
+                //    // 2. Initialize StreamWriter within a 'using' block
-                // }
+                //    // The 'true' parameter means "append" to the file. Use 'false' to overwrite.
+                //    using (StreamWriter writer = new StreamWriter(filePath, append: true))
+                //    {
+                //        foreach (int reading in sensorReadings)
+                //        {
+                //            string timestamp = DateTime.Now.ToString("yyyy-MM-dd HH:mm:ss");
+
+                //            // 3. Construct your string and write it
+                //            foreach (string _type in type)
+                //            {
+                //                string line = $"{timestamp} | {_type} {reading}";
+                //                writer.WriteLine(line);
+                //            }
+                            
+
+                //            // Optional: Console feedback
+                //            //Console.WriteLine($"Logged: {line}");
+                //        }
+                //    }
+                //    // File is automatically closed and saved here
+
+                //    //Console.WriteLine("Data capture complete.");
+                //}
+                //catch (IOException e)
+                //{
+                //    Console.WriteLine($"An error occurred: {e.Message}");
+                //}
+
+                // THE TRIPWIRE: Check the breakpoint after EVERY single instruction!
+                if (Breakpoint.HasValue && Cpu.PC == Breakpoint.Value)
+                {
+                    break; // Abort the frame loop immediately!
+                }
             }
+
         }
     }
 }

Core/Video/SmsVdp.cs

@@ -0,0 +1,194 @@
+using System;
+
+namespace Core.Video
+{
+    public class SmsVdp
+    {
+        // 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[] Registers { get; private set; } = new byte[16]; // 11 Hardware Control Registers
+        public int[] FrameBuffer { get; private set; } = new int[256 * 192];
+
+        // The Control Port State Machine (Port 0xBF)
+        private bool _isSecondControlByte = false;
+        private ushort _controlWord = 0;
+        private byte _readBuffer = 0;
+
+        private int _tStateCounter = 0;
+        private int _currentScanline = 0;
+        private byte _statusRegister = 0x00;
+
+        public bool InterruptPending => (_statusRegister & 0x80) != 0 && (Registers[1] & 0x20) != 0;
+
+        public byte ReadDataPort() // Port 0xBE
+        {
+            _isSecondControlByte = false; // Reading data resets the control latch
+            byte value = _readBuffer;
+            _readBuffer = VRAM[_controlWord & 0x3FFF];
+            _controlWord++;
+            return value;
+        }
+
+        public byte ReadControlPort() // Port 0xBF
+        {
+            _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, 
+            // the interrupt line gets stuck on forever.
+            _statusRegister = 0x00;
+
+            return currentStatus;
+        }
+
+        public void WriteDataPort(byte value) // Port 0xBE
+        {
+            _isSecondControlByte = false;
+            _readBuffer = value; 
+
+            int address = _controlWord & 0x3FFF;
+            int command = (_controlWord >> 14) & 0x03;
+
+            if (command == 3) // Code 3: Write to Color Palette (CRAM)
+            {
+                CRAM[address & 0x1F] = value;
+            }
+            else // Code 0, 1, 2: Write to VRAM
+            {
+                VRAM[address] = value;
+            }
+            _controlWord++; // Auto-increment so the Z80 can blast data fast
+        }
+
+        public void WriteControlPort(byte value) // Port 0xBF
+        {
+            if (!_isSecondControlByte)
+            {
+                // First byte arrives: Store it in the lower 8 bits
+                _controlWord = (ushort)((_controlWord & 0xFF00) | value);
+                _isSecondControlByte = true;
+            }
+            else
+            {
+                // Second byte arrives: Store it in the upper 8 bits and execute!
+                _controlWord = (ushort)((_controlWord & 0x00FF) | (value << 8));
+                _isSecondControlByte = false;
+
+                int command = (_controlWord >> 14) & 0x03;
+                
+                if (command == 0) // Code 0: Prep for VRAM Read
+                {
+                    _readBuffer = VRAM[_controlWord & 0x3FFF];
+                    _controlWord++;
+                }
+                else if (command == 2) // Code 2: Write to Internal VDP Register
+                {
+                    int regIndex = value & 0x0F;
+                    byte regData = (byte)(_controlWord & 0xFF);
+                    
+                    if (regIndex < 16) Registers[regIndex] = regData;
+                }
+            }
+        }
+
+        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;
+        }
+
+        public void Update(int tStates)
+        {
+            _tStateCounter += tStates;
+
+            // 228 T-States per scanline
+            if (_tStateCounter >= 228)
+            {
+                _tStateCounter -= 228;
+                _currentScanline++;
+
+                // Line 192 is the exact moment the screen finishes drawing!
+                if (_currentScanline == 192)
+                {
+                    _statusRegister |= 0x80; // Set Bit 7 (VBlank Flag) to 1
+
+                    RenderBackground(); // <--- DRAW THE FRAME!
+                }
+
+                // End of the NTSC frame (262 lines)
+                if (_currentScanline > 261)
+                {
+                    _currentScanline = 0;
+                }
+            }
+        }
+
+        private void RenderBackground()
+        {
+            // The Name Table base address is stored in VDP Register 2.
+            // It tells us where in VRAM the 32x24 screen grid starts.
+            ushort nameTableBase = (ushort)((Registers[2] & 0x0E) << 10);
+
+            // Loop through all 24 rows and 32 columns of the screen
+            for (int row = 0; row < 24; row++)
+            {
+                for (int col = 0; col < 32; col++)
+                {
+                    // 1. Read the 16-bit Tile instruction from the Name Table
+                    ushort nameTableAddr = (ushort)(nameTableBase + (row * 64) + (col * 2));
+                    byte lowByte = VRAM[nameTableAddr];
+                    byte highByte = VRAM[nameTableAddr + 1];
+                    ushort tileData = (ushort)((highByte << 8) | lowByte);
+
+                    // 2. Extract the Tile Index and Palette Info
+                    int tileIndex = tileData & 0x01FF;
+                    bool useSpritePalette = (tileData & 0x0800) != 0;
+
+                    // 3. Find the actual pixel data for this tile in VRAM
+                    // Each 8x8 tile takes exactly 32 bytes in memory
+                    ushort tileAddress = (ushort)(tileIndex * 32);
+
+                    // 4. Draw the 8x8 block of pixels!
+                    for (int y = 0; y < 8; y++)
+                    {
+                        // The SMS uses 4 bitplanes to make a single row of pixels.
+                        byte bp0 = VRAM[tileAddress + (y * 4) + 0];
+                        byte bp1 = VRAM[tileAddress + (y * 4) + 1];
+                        byte bp2 = VRAM[tileAddress + (y * 4) + 2];
+                        byte bp3 = VRAM[tileAddress + (y * 4) + 3];
+
+                        for (int x = 0; x < 8; x++)
+                        {
+                            // Combine 1 bit from each bitplane to get a color index (0-15)
+                            int shift = 7 - x;
+                            int colorIndex = ((bp0 >> shift) & 1) |
+                                            (((bp1 >> shift) & 1) << 1) |
+                                            (((bp2 >> shift) & 1) << 2) |
+                                            (((bp3 >> shift) & 1) << 3);
+
+                            // Find the raw SMS color in CRAM
+                            int paletteOffset = useSpritePalette ? 16 : 0;
+                            byte smsColor = CRAM[paletteOffset + colorIndex];
+
+                            // Translate SMS 00BBGGRR format to Windows 32-bit ARGB
+                            int r = (smsColor & 0x03) * 85;
+                            int g = ((smsColor >> 2) & 0x03) * 85;
+                            int b = ((smsColor >> 4) & 0x03) * 85;
+
+                            // Calculate where this pixel goes on the final 256x192 screen
+                            int pixelX = (col * 8) + x;
+                            int pixelY = (row * 8) + y;
+
+                            FrameBuffer[(pixelY * 256) + pixelX] = (255 << 24) | (r << 16) | (g << 8) | b;
+                        }
+                    }
+                }
+            }
+        }
+
+    }
+}

Desktop/DebuggerForm.Designer.cs

@@ -57,95 +57,95 @@
             lblFrameTime = new Label();
             richTextBox1 = new RichTextBox();
             button1 = new Button();
-            button2 = new Button();
+            CpuRun = new Button();
             SuspendLayout();
             // 
             // lblAF
             // 
             lblAF.AutoSize = true;
-            lblAF.Location = new Point(10, 7);
+            lblAF.Location = new Point(12, 9);
             lblAF.Margin = new Padding(2, 0, 2, 0);
             lblAF.Name = "lblAF";
-            lblAF.Size = new Size(26, 20);
+            lblAF.Size = new Size(33, 25);
             lblAF.TabIndex = 0;
             lblAF.Text = "AF";
             // 
             // lblBC
             // 
             lblBC.AutoSize = true;
-            lblBC.Location = new Point(9, 48);
+            lblBC.Location = new Point(11, 60);
             lblBC.Margin = new Padding(2, 0, 2, 0);
             lblBC.Name = "lblBC";
-            lblBC.Size = new Size(27, 20);
+            lblBC.Size = new Size(33, 25);
             lblBC.TabIndex = 1;
             lblBC.Text = "BC";
             // 
             // lblDE
             // 
             lblDE.AutoSize = true;
-            lblDE.Location = new Point(10, 100);
+            lblDE.Location = new Point(12, 125);
             lblDE.Margin = new Padding(2, 0, 2, 0);
             lblDE.Name = "lblDE";
-            lblDE.Size = new Size(28, 20);
+            lblDE.Size = new Size(34, 25);
             lblDE.TabIndex = 2;
             lblDE.Text = "DE";
             // 
             // lblHL
             // 
             lblHL.AutoSize = true;
-            lblHL.Location = new Point(10, 150);
+            lblHL.Location = new Point(12, 188);
             lblHL.Margin = new Padding(2, 0, 2, 0);
             lblHL.Name = "lblHL";
-            lblHL.Size = new Size(27, 20);
+            lblHL.Size = new Size(33, 25);
             lblHL.TabIndex = 3;
             lblHL.Text = "HL";
             // 
             // lblPC
             // 
             lblPC.AutoSize = true;
-            lblPC.Location = new Point(9, 200);
+            lblPC.Location = new Point(11, 250);
             lblPC.Margin = new Padding(2, 0, 2, 0);
             lblPC.Name = "lblPC";
-            lblPC.Size = new Size(26, 20);
+            lblPC.Size = new Size(33, 25);
             lblPC.TabIndex = 4;
             lblPC.Text = "PC";
             // 
             // lblSP
             // 
             lblSP.AutoSize = true;
-            lblSP.Location = new Point(9, 252);
+            lblSP.Location = new Point(11, 315);
             lblSP.Margin = new Padding(2, 0, 2, 0);
             lblSP.Name = "lblSP";
-            lblSP.Size = new Size(25, 20);
+            lblSP.Size = new Size(32, 25);
             lblSP.TabIndex = 6;
             lblSP.Text = "SP";
             // 
             // lblFlags
             // 
             lblFlags.AutoSize = true;
-            lblFlags.Location = new Point(88, 52);
+            lblFlags.Location = new Point(110, 65);
             lblFlags.Margin = new Padding(2, 0, 2, 0);
             lblFlags.Name = "lblFlags";
-            lblFlags.Size = new Size(43, 20);
+            lblFlags.Size = new Size(53, 25);
             lblFlags.TabIndex = 7;
             lblFlags.Text = "Flags";
             // 
             // lblTStates
             // 
             lblTStates.AutoSize = true;
-            lblTStates.Location = new Point(88, 7);
+            lblTStates.Location = new Point(110, 9);
             lblTStates.Margin = new Padding(2, 0, 2, 0);
             lblTStates.Name = "lblTStates";
-            lblTStates.Size = new Size(63, 20);
+            lblTStates.Size = new Size(75, 25);
             lblTStates.TabIndex = 8;
             lblTStates.Text = "T-States";
             // 
             // txtMemoryStart
             // 
-            txtMemoryStart.Location = new Point(300, 21);
+            txtMemoryStart.Location = new Point(375, 26);
             txtMemoryStart.Margin = new Padding(2);
             txtMemoryStart.Name = "txtMemoryStart";
-            txtMemoryStart.Size = new Size(121, 27);
+            txtMemoryStart.Size = new Size(150, 31);
             txtMemoryStart.TabIndex = 9;
             txtMemoryStart.Text = "Memory Start";
             txtMemoryStart.TextAlign = HorizontalAlignment.Center;
@@ -153,10 +153,10 @@
             // 
             // btnRefreshMemory
             // 
-            btnRefreshMemory.Location = new Point(425, 21);
+            btnRefreshMemory.Location = new Point(531, 26);
             btnRefreshMemory.Margin = new Padding(2);
             btnRefreshMemory.Name = "btnRefreshMemory";
-            btnRefreshMemory.Size = new Size(90, 27);
+            btnRefreshMemory.Size = new Size(112, 34);
             btnRefreshMemory.TabIndex = 14;
             btnRefreshMemory.Text = "Refresh Memory";
             btnRefreshMemory.UseVisualStyleBackColor = true;
@@ -164,109 +164,117 @@
             // 
             // txtMemoryView
             // 
-            txtMemoryView.Location = new Point(88, 80);
+            txtMemoryView.Location = new Point(110, 100);
             txtMemoryView.Margin = new Padding(2);
             txtMemoryView.Name = "txtMemoryView";
-            txtMemoryView.Size = new Size(443, 895);
+            txtMemoryView.Size = new Size(553, 1118);
             txtMemoryView.TabIndex = 15;
             txtMemoryView.Text = "Memory View Window";
             // 
             // lstDisassembly
             // 
             lstDisassembly.FormattingEnabled = true;
-            lstDisassembly.Location = new Point(567, 8);
+            lstDisassembly.ItemHeight = 25;
+            lstDisassembly.Location = new Point(709, 10);
             lstDisassembly.Margin = new Padding(2);
             lstDisassembly.Name = "lstDisassembly";
-            lstDisassembly.Size = new Size(252, 264);
+            lstDisassembly.Size = new Size(314, 329);
             lstDisassembly.TabIndex = 16;
             // 
             // lstStack
             // 
             lstStack.FormattingEnabled = true;
-            lstStack.Location = new Point(823, 8);
+            lstStack.ItemHeight = 25;
+            lstStack.Location = new Point(1029, 10);
             lstStack.Margin = new Padding(2);
             lstStack.Name = "lstStack";
-            lstStack.Size = new Size(130, 264);
+            lstStack.Size = new Size(162, 329);
             lstStack.TabIndex = 17;
             // 
             // label1
             // 
             label1.AutoSize = true;
-            label1.Location = new Point(568, 298);
+            label1.Location = new Point(710, 372);
+            label1.Margin = new Padding(4, 0, 4, 0);
             label1.Name = "label1";
-            label1.Size = new Size(81, 20);
+            label1.Size = new Size(97, 25);
             label1.TabIndex = 19;
             label1.Text = "Breakpoint";
             // 
             // txtBreakpoint
             // 
-            txtBreakpoint.Location = new Point(655, 295);
+            txtBreakpoint.Location = new Point(819, 369);
+            txtBreakpoint.Margin = new Padding(4);
             txtBreakpoint.Name = "txtBreakpoint";
-            txtBreakpoint.Size = new Size(125, 27);
+            txtBreakpoint.Size = new Size(155, 31);
             txtBreakpoint.TabIndex = 20;
             // 
             // label2
             // 
             label2.AutoSize = true;
-            label2.Location = new Point(233, 21);
+            label2.Location = new Point(291, 26);
+            label2.Margin = new Padding(4, 0, 4, 0);
             label2.Name = "label2";
-            label2.Size = new Size(62, 20);
+            label2.Size = new Size(77, 25);
             label2.TabIndex = 21;
             label2.Text = "Address";
             // 
             // lblIX
             // 
             lblIX.AutoSize = true;
-            lblIX.Location = new Point(9, 298);
+            lblIX.Location = new Point(11, 372);
             lblIX.Margin = new Padding(2, 0, 2, 0);
             lblIX.Name = "lblIX";
-            lblIX.Size = new Size(22, 20);
+            lblIX.Size = new Size(28, 25);
             lblIX.TabIndex = 22;
             lblIX.Text = "IX";
             // 
             // lblIY
             // 
             lblIY.AutoSize = true;
-            lblIY.Location = new Point(10, 344);
+            lblIY.Location = new Point(12, 430);
             lblIY.Margin = new Padding(2, 0, 2, 0);
             lblIY.Name = "lblIY";
-            lblIY.Size = new Size(21, 20);
+            lblIY.Size = new Size(27, 25);
             lblIY.TabIndex = 23;
             lblIY.Text = "IY";
             // 
             // lblIff1
             // 
             lblIff1.AutoSize = true;
-            lblIff1.Location = new Point(567, 411);
+            lblIff1.Location = new Point(709, 514);
+            lblIff1.Margin = new Padding(4, 0, 4, 0);
             lblIff1.Name = "lblIff1";
-            lblIff1.Size = new Size(35, 20);
+            lblIff1.Size = new Size(45, 25);
             lblIff1.TabIndex = 24;
             lblIff1.Text = "IFF1";
             // 
             // lblIff2
             // 
             lblIff2.AutoSize = true;
-            lblIff2.Location = new Point(567, 458);
+            lblIff2.Location = new Point(709, 572);
+            lblIff2.Margin = new Padding(4, 0, 4, 0);
             lblIff2.Name = "lblIff2";
-            lblIff2.Size = new Size(35, 20);
+            lblIff2.Size = new Size(45, 25);
             lblIff2.TabIndex = 25;
             lblIff2.Text = "IFF2";
             // 
             // lblIE
             // 
             lblIE.AutoSize = true;
-            lblIE.Location = new Point(568, 370);
+            lblIE.Location = new Point(710, 462);
+            lblIE.Margin = new Padding(4, 0, 4, 0);
             lblIE.Name = "lblIE";
-            lblIE.Size = new Size(109, 20);
+            lblIE.Size = new Size(133, 25);
             lblIE.TabIndex = 26;
             lblIE.Text = "Interrupt Mode";
             // 
             // btnReset
             // 
-            btnReset.Location = new Point(651, 327);
+            btnReset.Location = new Point(814, 409);
             btnReset.Margin = new Padding(2);
             btnReset.Name = "btnReset";
-            btnReset.Size = new Size(132, 27);
+            btnReset.Size = new Size(165, 34);
             btnReset.TabIndex = 27;
             btnReset.Text = "Set Breakpoint";
             btnReset.UseVisualStyleBackColor = true;
@@ -281,69 +289,72 @@
             // lblFrames
             // 
             lblFrames.AutoSize = true;
-            lblFrames.Location = new Point(567, 682);
+            lblFrames.Location = new Point(709, 852);
             lblFrames.Margin = new Padding(2, 0, 2, 0);
             lblFrames.Name = "lblFrames";
-            lblFrames.Size = new Size(124, 20);
+            lblFrames.Size = new Size(149, 25);
             lblFrames.TabIndex = 28;
             lblFrames.Text = "Frames Rendered";
             // 
             // lblFPS
             // 
             lblFPS.AutoSize = true;
-            lblFPS.Location = new Point(659, 759);
+            lblFPS.Location = new Point(824, 949);
             lblFPS.Margin = new Padding(2, 0, 2, 0);
             lblFPS.Name = "lblFPS";
-            lblFPS.Size = new Size(32, 20);
+            lblFPS.Size = new Size(41, 25);
             lblFPS.TabIndex = 29;
             lblFPS.Text = "FPS";
             // 
             // lblFrameTime
             // 
             lblFrameTime.AutoSize = true;
-            lblFrameTime.Location = new Point(604, 718);
+            lblFrameTime.Location = new Point(755, 898);
             lblFrameTime.Margin = new Padding(2, 0, 2, 0);
             lblFrameTime.Name = "lblFrameTime";
-            lblFrameTime.Size = new Size(87, 20);
+            lblFrameTime.Size = new Size(104, 25);
             lblFrameTime.TabIndex = 30;
             lblFrameTime.Text = "Frame Time";
             // 
             // richTextBox1
             // 
             richTextBox1.Enabled = false;
-            richTextBox1.Location = new Point(567, 509);
+            richTextBox1.Location = new Point(709, 636);
+            richTextBox1.Margin = new Padding(4);
             richTextBox1.Name = "richTextBox1";
             richTextBox1.ReadOnly = true;
-            richTextBox1.Size = new Size(304, 128);
+            richTextBox1.Size = new Size(379, 159);
             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
             // 
-            button1.Location = new Point(555, 824);
+            button1.Location = new Point(694, 1030);
+            button1.Margin = new Padding(4);
             button1.Name = "button1";
-            button1.Size = new Size(94, 29);
+            button1.Size = new Size(118, 36);
             button1.TabIndex = 33;
             button1.Text = "CPU Step";
             button1.UseVisualStyleBackColor = true;
             button1.Click += btnStep_Click;
             // 
-            // button2
+            // CpuRun
             // 
-            button2.Location = new Point(555, 883);
+            CpuRun.Location = new Point(694, 1104);
-            button2.Name = "button2";
+            CpuRun.Margin = new Padding(4);
-            button2.Size = new Size(94, 29);
+            CpuRun.Name = "CpuRun";
-            button2.TabIndex = 34;
+            CpuRun.Size = new Size(118, 36);
-            button2.Text = "CPU Run";
+            CpuRun.TabIndex = 34;
-            button2.UseVisualStyleBackColor = true;
+            CpuRun.Text = "CPU Run";
-            button2.Click += btnStep_Click;
+            CpuRun.UseVisualStyleBackColor = true;
+            CpuRun.Click += CpuRun_Click;
             // 
             // DebuggerForm
             // 
-            AutoScaleDimensions = new SizeF(8F, 20F);
+            AutoScaleDimensions = new SizeF(10F, 25F);
             AutoScaleMode = AutoScaleMode.Font;
-            ClientSize = new Size(965, 990);
+            ClientSize = new Size(1206, 1238);
-            Controls.Add(button2);
+            Controls.Add(CpuRun);
             Controls.Add(button1);
             Controls.Add(richTextBox1);
             Controls.Add(lblFrameTime);
@@ -402,13 +413,13 @@
         private Label lblIff2;
         private Label lblIE;
         private Button btnReset;
-        private System.Windows.Forms.Timer uiUpdateTimer;
         private Label lblFrames;
         private Label lblFPS;
         private Label lblFrameTime;
         private RichTextBox richTextBox1;
         private Button button1;
-        private Button button2;
+        private Button CpuRun;
+        public System.Windows.Forms.Timer uiUpdateTimer;
         //private TextBox textBox4;
     }
 }

Desktop/DebuggerForm.cs

@@ -27,11 +27,36 @@ namespace Desktop
             _mainForm = mainForm;
         }
 
+        private void CpuRun_Click(object sender, EventArgs e)
+        {
+            if (_mainForm.IsRunning)
+            {
+                // Stop the machine
+                _mainForm.StopEmulator();
+                CpuRun.Text = "CPU Run";
+
+                // Stop the live UI updates and do one final manual refresh
+                uiUpdateTimer.Stop();
+                UpdateDisplay();
+            }
+            else
+            {
+                // 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();
+            }
+        }
+
         private void btnStep_Click(object sender, EventArgs e)
         {
             try
             {
-                _cpu.Step();
+                // Ask the main form to step the WHOLE machine, not just the Z80!
+                _mainForm.StepEmulator();
                 UpdateDisplay();
             }
             catch (Exception ex)
@@ -57,7 +82,7 @@ namespace Desktop
             UpdateDisplay();
         }
 
-        private void uiUpdateTimer_Tick(object sender, EventArgs e)
+        public void uiUpdateTimer_Tick(object sender, EventArgs e)
         {
             UpdateDisplay();
         }
@@ -180,6 +205,9 @@ namespace Desktop
                     case 0x02: mnemonic = "LD (BC), A"; break;
                     // --- 16-Bit Increments ---
                     case 0x03: mnemonic = "INC BC"; break;
+                    case 0x07:
+                        mnemonic = "RLCA";
+                        break;
                     case 0x08:
                         mnemonic = "EX AF, AF'";
                         break;

Desktop/Form1.Designer.cs

@@ -29,32 +29,48 @@
         private void InitializeComponent()
         {
             button1 = new Button();
+            pbScreen = new PictureBox();
+            ((System.ComponentModel.ISupportInitialize)pbScreen).BeginInit();
             SuspendLayout();
             // 
             // button1
             // 
-            button1.Location = new Point(304, 268);
+            button1.Location = new Point(1294, 13);
+            button1.Margin = new Padding(4, 4, 4, 4);
             button1.Name = "button1";
-            button1.Size = new Size(94, 29);
+            button1.Size = new Size(118, 36);
             button1.TabIndex = 0;
             button1.Text = "button1";
             button1.UseVisualStyleBackColor = true;
             button1.Click += button1_Click;
             // 
+            // pbScreen
+            // 
+            pbScreen.Location = new Point(23, 59);
+            pbScreen.Name = "pbScreen";
+            pbScreen.Size = new Size(1390, 760);
+            pbScreen.SizeMode = PictureBoxSizeMode.Zoom;
+            pbScreen.TabIndex = 1;
+            pbScreen.TabStop = false;
+            // 
             // Form1
             // 
-            AutoScaleDimensions = new SizeF(8F, 20F);
+            AutoScaleDimensions = new SizeF(10F, 25F);
             AutoScaleMode = AutoScaleMode.Font;
-            ClientSize = new Size(800, 450);
+            ClientSize = new Size(1425, 842);
+            Controls.Add(pbScreen);
             Controls.Add(button1);
+            Margin = new Padding(4, 4, 4, 4);
             Name = "Form1";
             Text = "Form1";
             Click += button1_Click;
+            ((System.ComponentModel.ISupportInitialize)pbScreen).EndInit();
             ResumeLayout(false);
         }
 
         #endregion
 
         private Button button1;
+        private PictureBox pbScreen;
     }
 }

Desktop/Form1.cs

@@ -1,12 +1,21 @@
 using System.Reflection;
 using System.Reflection.PortableExecutable;
 using Core;
+using System.Threading.Tasks;
+using System.Drawing.Imaging;
+using System.Runtime.InteropServices;
+using System.Windows.Forms;
+
 namespace Desktop
 {
     public partial class Form1 : Form
     {
         private SmsMachine _machine = null!;
         private DebuggerForm _debugger;
+        private Bitmap _screenBitmap = new Bitmap(256, 192, PixelFormat.Format32bppArgb);
+
+
+        public bool IsRunning { get; private set; } = false;
 
         public ushort? Breakpoint
         {
@@ -20,23 +29,67 @@ namespace Desktop
             _machine = new SmsMachine();
         }
 
+        private void DrawScreen()
+        {
+            // Rapidly copy our VDP FrameBuffer 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);
+            _screenBitmap.UnlockBits(data);
+
+            // Update the PictureBox
+            pbScreen.Image = _screenBitmap;
+        }
+
+        public void StartEmulator()
+        {
+            if (IsRunning) return;
+            IsRunning = true;
+
+            // Fire off a background task so we don't freeze the Windows UI!
+            Task.Run(() =>
+            {
+                while (IsRunning)
+                {
+                    _machine.RunFrame();
+
+                    Invoke((System.Windows.Forms.MethodInvoker)delegate { DrawScreen(); });
+
+                    // Safety catch: If we hit a breakpoint while running, stop the loop!
+                    if (_machine.Breakpoint.HasValue && _machine.Cpu.PC == _machine.Breakpoint.Value)
+                    {
+                        IsRunning = false;
+
+                        // Optional: Force the debugger UI to update immediately so you see it!
+                        Invoke((System.Windows.Forms.MethodInvoker)delegate { _debugger?.uiUpdateTimer_Tick(null, EventArgs.Empty); });
+                    }
+                    else
+                    {
+                        // Only throttle the speed if we are actively running
+                        Thread.Sleep(16);
+                    }
+                }
+            });
+        }
+
+        public void StopEmulator()
+        {
+            IsRunning = false;
+        }
+
+
+        public void StepEmulator()
+        {
+            _machine.StepMachine();
+        }
+
         private void button1_Click(object sender, EventArgs e)
         {
             // 1. Load a commercial Master System ROM!
             
                 byte[] rom = File.ReadAllBytes(@"C:\Parsons\Local Code Projects\ParsonsMasterSystem2026\Desktop\ROMS\Golden Axe Warrior.sms");
-            
-            
-            try
-            {
 
                 // 2. Jam it into the Sega Mapper
                 _machine.LoadCartridge(rom);
-            }
-            catch (Exception ex)
-            {
-                MessageBox.Show(ex.Message);
-            }
 
             // 3. Open the Debugger to look around
             if (_debugger == null || _debugger.IsDisposed)