Added original 16k speccy (even though it sucks)

BizHawk.Emulation.Cores/BizHawk.Emulation.Cores.csproj

@@ -271,6 +271,7 @@
     <Compile Include="Computers\SinclairSpectrum\Hardware\TapeBlockSetPlayer.cs" />
     <Compile Include="Computers\SinclairSpectrum\Hardware\TapeDataBlockPlayer.cs" />
     <Compile Include="Computers\SinclairSpectrum\Hardware\TapeFilePlayer.cs" />
+    <Compile Include="Computers\SinclairSpectrum\Machine\ZXSpectrum16K\ZX16.cs" />
     <Compile Include="Computers\SinclairSpectrum\SoundProviderMixer.cs" />
     <Compile Include="Computers\SinclairSpectrum\Machine\MachineType.cs" />
     <Compile Include="Computers\SinclairSpectrum\Machine\SpectrumBase.cs" />

BizHawk.Emulation.Cores/Computers/SinclairSpectrum/Machine/MachineType.cs

@@ -8,6 +8,11 @@ namespace BizHawk.Emulation.Cores.Computers.SinclairSpectrum
 {
     public enum MachineType
     {
+        /// <summary>
+        /// Original Sinclair Spectrum 16K model
+        /// </summary>
+        ZXSpectrum16,
+
         /// <summary>
         /// Sinclair Spectrum 48K model
         /// </summary>

BizHawk.Emulation.Cores/Computers/SinclairSpectrum/Machine/ZXSpectrum16K/ZX16.cs

@@ -0,0 +1,169 @@
+using BizHawk.Emulation.Cores.Components.Z80A;
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace BizHawk.Emulation.Cores.Computers.SinclairSpectrum
+{
+    public class ZX16 : ZX48
+    {
+        #region Construction
+
+        /// <summary>
+        /// Main constructor
+        /// </summary>
+        /// <param name="spectrum"></param>
+        /// <param name="cpu"></param>
+        public ZX16(ZXSpectrum spectrum, Z80A cpu, byte[] file) 
+            : base(spectrum, cpu, file)
+        {
+
+        }
+
+        #endregion
+
+
+        #region Memory
+
+        /* 48K Spectrum has NO memory paging
+         * 
+         *  
+                   | Bank 0 |
+                   |        |
+                   |        |
+                   | screen |
+            0x4000 +--------+
+                   | ROM 0  |
+                   |        |
+                   |        |
+                   |        |
+            0x0000 +--------+
+        */
+
+        /// <summary>
+        /// Simulates reading from the bus (no contention)
+        /// Paging should be handled here
+        /// </summary>
+        /// <param name="addr"></param>
+        /// <returns></returns>
+        public override byte ReadBus(ushort addr)
+        {
+            int divisor = addr / 0x4000;
+            // paging logic goes here
+
+            if (divisor > 1)
+            {
+                // memory does not exist
+                return 0xff;
+            }
+
+            var bank = Memory[divisor];
+            var index = addr % 0x4000;
+            return bank[index];
+        }
+
+        /// <summary>
+        /// Simulates writing to the bus (no contention)
+        /// Paging should be handled here
+        /// </summary>
+        /// <param name="addr"></param>
+        /// <param name="value"></param>
+        public override void WriteBus(ushort addr, byte value)
+        {
+            int divisor = addr / 0x4000;
+            // paging logic goes here
+
+            if (divisor > 1)
+            {
+                // memory does not exist
+                return;
+            }
+
+            var bank = Memory[divisor];
+            var index = addr % 0x4000;
+            bank[index] = value;
+        }
+
+        /// <summary>
+        /// Reads a byte of data from a specified memory address
+        /// (with memory contention if appropriate)
+        /// </summary>
+        /// <param name="addr"></param>
+        /// <returns></returns>
+        public override byte ReadMemory(ushort addr)
+        {
+            var data = ReadBus(addr);
+            if ((addr & 0xC000) == 0x4000)
+            {
+                // addr is in RAM not ROM - apply memory contention if neccessary
+                if (addr >= 0x8000)
+                {
+                    data = 0xFF;
+                }
+                else
+                {
+                    var delay = GetContentionValue(CurrentFrameCycle);
+                    CPU.TotalExecutedCycles += delay;
+                }                
+            }
+            return data;
+        }
+
+        /// <summary>
+        /// Writes a byte of data to a specified memory address
+        /// (with memory contention if appropriate)
+        /// </summary>
+        /// <param name="addr"></param>
+        /// <param name="value"></param>
+        public override void WriteMemory(ushort addr, byte value)
+        {
+            if (addr < 0x4000)
+            {
+                // Do nothing - we cannot write to ROM
+                return;
+            }
+            else if (addr >= 0x8000)
+            {
+                // memory does not exist
+                return;
+            }
+            else if (addr < 0x8000)
+            {
+                // possible contended RAM
+                var delay = GetContentionValue(CurrentFrameCycle);
+                CPU.TotalExecutedCycles += delay;
+            }
+
+            WriteBus(addr, value);
+        }
+
+        public override void ReInitMemory()
+        {
+            if (Memory.ContainsKey(0))
+                Memory[0] = ROM0;
+            else
+                Memory.Add(0, ROM0);
+
+            if (Memory.ContainsKey(1))
+                Memory[1] = RAM1;
+            else
+                Memory.Add(1, RAM1);            
+        }
+
+        /// <summary>
+        /// Sets up the ROM
+        /// </summary>
+        /// <param name="buffer"></param>
+        /// <param name="startAddress"></param>
+        public override void InitROM(RomData romData)
+        {
+            RomData = romData;
+            // for 16/48k machines only ROM0 is used (no paging)
+            RomData.RomBytes?.CopyTo(ROM0, 0);
+        }
+
+        #endregion
+    }
+}

BizHawk.Emulation.Cores/Computers/SinclairSpectrum/ZXSpectrum.cs

@@ -36,6 +36,10 @@ namespace BizHawk.Emulation.Cores.Computers.SinclairSpectrum
 
             switch (SyncSettings.MachineType)
             {
+                case MachineType.ZXSpectrum16:
+                    ControllerDefinition = ZXSpectrumControllerDefinition;
+                    Init(MachineType.ZXSpectrum16, SyncSettings.BorderType, SyncSettings.TapeLoadSpeed, _file);
+                    break;
                 case MachineType.ZXSpectrum48:
                     ControllerDefinition = ZXSpectrumControllerDefinition;                    
                     Init(MachineType.ZXSpectrum48, SyncSettings.BorderType, SyncSettings.TapeLoadSpeed, _file);
@@ -132,6 +136,12 @@ namespace BizHawk.Emulation.Cores.Computers.SinclairSpectrum
             // setup the emulated model based on the MachineType
             switch (machineType)
             {
+                case MachineType.ZXSpectrum16:
+                    _machine = new ZX16(this, _cpu, file);
+                    var _systemRom16 = GetFirmware(0x4000, "48ROM");
+                    var romData16 = RomData.InitROM(machineType, _systemRom16);
+                    _machine.InitROM(romData16);
+                    break;
                 case MachineType.ZXSpectrum48:
                     _machine = new ZX48(this, _cpu, file);
                     var _systemRom = GetFirmware(0x4000, "48ROM");