Fixed Plus 3 Snapshot saving and loading

Core/Memory/MemoryBus.cs

@@ -18,6 +18,8 @@ namespace Core.Memory
         private byte _port7FFD = 0;
         private byte _port1FFD = 0;
         private bool _pagingDisabled = false;
+        public byte Port7FFD => _port7FFD;
+        public int CurrentRamBankSlot3 => _currentRamBankSlot3;
 
         public MemoryBus()
         {
@@ -94,6 +96,11 @@ namespace Core.Memory
                 default: return -1; // -1 means it is pointing to a ROM chip!
             }
         }
+        public byte[] GetRamBank(int index)
+        {
+            return _ramBanks[index];
+        }
+
         public byte Read(ushort address)
         {
             int slot = address >> 14; // Find the 16KB Slot (0, 1, 2, or 3)

Core/SpectrumMachine.cs

@@ -289,61 +289,17 @@ namespace Core
         // SNAPSHOT MANAGEMENT (.SNA)
         // ====================================================================
 
-        public void LoadSnapshot(byte[] snaData)
+        // ====================================================================
-        {
+        // SNAPSHOT MANAGEMENT (.SNA)
-            if (snaData.Length != 49179)
+        // ====================================================================
-                throw new Exception("Invalid 48K SNA File Size!");
-
-            // 1. Load CPU Registers
-            Cpu.I = snaData[0];
-            Cpu.HL_Prime.Word = (ushort)(snaData[1] | (snaData[2] << 8));
-            Cpu.DE_Prime.Word = (ushort)(snaData[3] | (snaData[4] << 8));
-            Cpu.BC_Prime.Word = (ushort)(snaData[5] | (snaData[6] << 8));
-            Cpu.AF_Prime.Word = (ushort)(snaData[7] | (snaData[8] << 8));
-
-            Cpu.HL.Word = (ushort)(snaData[9] | (snaData[10] << 8));
-            Cpu.DE.Word = (ushort)(snaData[11] | (snaData[12] << 8));
-            Cpu.BC.Word = (ushort)(snaData[13] | (snaData[14] << 8));
-            Cpu.IY.Word = (ushort)(snaData[15] | (snaData[16] << 8));
-            Cpu.IX.Word = (ushort)(snaData[17] | (snaData[18] << 8));
-
-            bool iff2 = (snaData[19] & 0x04) != 0;
-            // Note: If IFF1/IFF2 have private setters in Z80.cs, you may need to 
-            // trigger an EI/DI instruction or temporarily unlock them.
-            // Assuming they are public/internal for now based on previous code:
-
-            Cpu.R = snaData[20];
-            Cpu.AF.Word = (ushort)(snaData[21] | (snaData[22] << 8));
-            Cpu.SP = (ushort)(snaData[23] | (snaData[24] << 8));
-
-            // Set Interrupt Mode (Assuming you add a setter to Z80.InterruptMode if it's private)
-            // Cpu.InterruptMode = snaData[25]; 
-
-            // THE BUG FIX: Restore the ULA Border Color!
-            IoBus.BorderColourIndex = snaData[26];
-
-            // 2. Load the 48K RAM Dump
-            for (int i = 0; i < 49152; i++)
-            {
-                Memory.Write((ushort)(0x4000 + i), snaData[27 + i]);
-            }
-
-            // 3. Pop the Program Counter off the stack to resume
-            byte pcLow = Memory.Read(Cpu.SP);
-            Cpu.SP++;
-            byte pcHigh = Memory.Read(Cpu.SP);
-            Cpu.SP++;
-            Cpu.PC = (ushort)((pcHigh << 8) | pcLow);
-        }
 
         public void SaveSnapshot(string filepath)
         {
-            // Back up the live state BEFORE modifying the stack
             ushort originalSP = Cpu.SP;
             byte originalMemLow = Memory.Read((ushort)(Cpu.SP - 2));
             byte originalMemHigh = Memory.Read((ushort)(Cpu.SP - 1));
 
-            // Push the PC onto the stack
+            // Push PC for 48K compatibility
             Cpu.SP -= 2;
             Memory.Write(Cpu.SP, (byte)(Cpu.PC & 0xFF));
             Memory.Write((ushort)(Cpu.SP + 1), (byte)(Cpu.PC >> 8));
@@ -351,6 +307,7 @@ namespace Core
             using (System.IO.FileStream fs = new System.IO.FileStream(filepath, System.IO.FileMode.Create))
             using (System.IO.BinaryWriter bw = new System.IO.BinaryWriter(fs))
             {
+                // --- 27 BYTE HEADER ---
                 bw.Write(Cpu.I);
                 bw.Write(Cpu.HL_Prime.Low); bw.Write(Cpu.HL_Prime.High);
                 bw.Write(Cpu.DE_Prime.Low); bw.Write(Cpu.DE_Prime.High);
@@ -370,9 +327,34 @@ namespace Core
                 bw.Write((byte)Cpu.InterruptMode);
                 bw.Write(IoBus.BorderColourIndex);
 
-                for (int i = 0x4000; i <= 0xFFFF; i++)
+                if (CurrentModel == MachineModel.Spectrum48K)
                 {
-                    bw.Write(Memory.Read((ushort)i));
+                    // --- 48K FORMAT (49,179 Bytes) ---
+                    for (int i = 0x4000; i <= 0xFFFF; i++) bw.Write(Memory.Read((ushort)i));
+                }
+                else
+                {
+                    // --- 128K FORMAT (131,103 Bytes) ---
+                    int activeBank = Memory.CurrentRamBankSlot3;
+
+                    bw.Write(Memory.GetRamBank(5)); // 0x4000 - 0x7FFF
+                    bw.Write(Memory.GetRamBank(2)); // 0x8000 - 0xBFFF
+                    bw.Write(Memory.GetRamBank(activeBank)); // 0xC000 - 0xFFFF
+
+                    // 128K Extensions
+                    bw.Write((byte)(Cpu.PC & 0xFF));
+                    bw.Write((byte)(Cpu.PC >> 8));
+                    bw.Write(Memory.Port7FFD);
+                    bw.Write((byte)0); // TR-DOS ROM (0 = unused)
+
+                    // Write the remaining 5 unpaged banks
+                    for (int i = 0; i < 8; i++)
+                    {
+                        if (i != 5 && i != 2 && i != activeBank)
+                        {
+                            bw.Write(Memory.GetRamBank(i));
+                        }
+                    }
                 }
             }
 
@@ -381,5 +363,79 @@ namespace Core
             Memory.Write((ushort)(originalSP - 2), originalMemLow);
             Memory.Write((ushort)(originalSP - 1), originalMemHigh);
         }
+
+        public void LoadSnapshot(byte[] snaData)
+        {
+            bool is128K = snaData.Length == 131103;
+
+            if (snaData.Length != 49179 && !is128K)
+                throw new Exception($"Invalid SNA File Size! Got {snaData.Length} bytes.");
+
+            // Force the machine into the correct mode
+            SetMachineModel(is128K ? MachineModel.SpectrumPlus2A : MachineModel.Spectrum48K);
+
+            // 1. Load Header
+            Cpu.I = snaData[0];
+            Cpu.HL_Prime.Word = (ushort)(snaData[1] | (snaData[2] << 8));
+            Cpu.DE_Prime.Word = (ushort)(snaData[3] | (snaData[4] << 8));
+            Cpu.BC_Prime.Word = (ushort)(snaData[5] | (snaData[6] << 8));
+            Cpu.AF_Prime.Word = (ushort)(snaData[7] | (snaData[8] << 8));
+
+            Cpu.HL.Word = (ushort)(snaData[9] | (snaData[10] << 8));
+            Cpu.DE.Word = (ushort)(snaData[11] | (snaData[12] << 8));
+            Cpu.BC.Word = (ushort)(snaData[13] | (snaData[14] << 8));
+            Cpu.IY.Word = (ushort)(snaData[15] | (snaData[16] << 8));
+            Cpu.IX.Word = (ushort)(snaData[17] | (snaData[18] << 8));
+
+            if ((snaData[19] & 0x04) != 0) { Cpu.ExecuteOpcode(0xFB); /* Fake EI */ }
+            else { Cpu.ExecuteOpcode(0xF3); /* Fake DI */ }
+
+            Cpu.R = snaData[20];
+            Cpu.AF.Word = (ushort)(snaData[21] | (snaData[22] << 8));
+            Cpu.SP = (ushort)(snaData[23] | (snaData[24] << 8));
+
+            if (snaData[25] == 0) Cpu.ExecuteOpcode(0x46); // IM 0
+            else if (snaData[25] == 1) Cpu.ExecuteOpcode(0x56); // IM 1
+            else if (snaData[25] == 2) Cpu.ExecuteOpcode(0x5E); // IM 2
+
+            IoBus.BorderColourIndex = snaData[26];
+
+            // 2. Load RAM
+            if (!is128K)
+            {
+                for (int i = 0; i < 49152; i++) Memory.Write((ushort)(0x4000 + i), snaData[27 + i]);
+
+                byte pcLow = Memory.Read(Cpu.SP); Cpu.SP++;
+                byte pcHigh = Memory.Read(Cpu.SP); Cpu.SP++;
+                Cpu.PC = (ushort)((pcHigh << 8) | pcLow);
+            }
+            else
+            {
+                Cpu.PC = (ushort)(snaData[49179] | (snaData[49180] << 8));
+                byte port7FFD = snaData[49181];
+
+                // THE TOASTRACK FIX: Force Amstrad ROMs into Toastrack compatibility mode!
+                IoBus.WritePort(0x1FFD, 0x04);
+                IoBus.WritePort(0x7FFD, port7FFD);
+
+                int activeBank = port7FFD & 0x07;
+
+                // Load the 3 visible memory chunks
+                Array.Copy(snaData, 27, Memory.GetRamBank(5), 0, 16384);
+                Array.Copy(snaData, 16411, Memory.GetRamBank(2), 0, 16384);
+                Array.Copy(snaData, 32795, Memory.GetRamBank(activeBank), 0, 16384);
+
+                // Load the remaining 5 hidden memory banks
+                int offset = 49183;
+                for (int i = 0; i < 8; i++)
+                {
+                    if (i != 5 && i != 2 && i != activeBank)
+                    {
+                        Array.Copy(snaData, offset, Memory.GetRamBank(i), 0, 16384);
+                        offset += 16384;
+                    }
+                }
+            }
+        }
     }
 }