Add Bios INT 12h to report installed memory size.

src/Spice86.Core/Emulator/InterruptHandlers/Bios/SystemBiosInt12Handler.cs

@@ -0,0 +1,31 @@
+namespace Spice86.Core.Emulator.InterruptHandlers.Bios;
+
+using Spice86.Core.Emulator.CPU;
+using Spice86.Core.Emulator.Memory;
+using Spice86.Shared.Interfaces;
+
+/// <summary>
+///     INT 12h handler. Reports how many kb of base memory is installed.
+/// </summary>
+public class SystemBiosInt12Handler : InterruptHandler {
+    private readonly BiosDataArea _biosDataArea;
+
+    /// <summary>
+    ///     Initializes a new instance.
+    /// </summary>
+    /// <param name="memory"></param>
+    /// <param name="cpu"></param>
+    /// <param name="biosDataArea"></param>
+    /// <param name="loggerService"></param>
+    public SystemBiosInt12Handler(IMemory memory, Cpu cpu, BiosDataArea biosDataArea, ILoggerService loggerService) : base(memory, cpu, loggerService) {
+        _biosDataArea = biosDataArea;
+    }
+
+    /// <inheritdoc />
+    public override byte VectorNumber => 0x12;
+
+    /// <inheritdoc />
+    public override void Run() {
+        _state.AX = _biosDataArea.ConventionalMemorySizeKb;
+    }
+}

src/Spice86.Core/Emulator/Memory/BiosDataArea.cs

@@ -40,7 +40,10 @@ public BiosDataArea(IByteReaderWriter byteReaderWriter) : base(byteReaderWriter,
 
     // Padding at 0x12
 
-    public ushort MemSizeKb { get => UInt16[0x13]; set => UInt16[0x13] = value; }
+    /// <summary>
+    /// Gets or sets the amount of installed conventional memory in KB.
+    /// </summary>
+    public ushort ConventionalMemorySizeKb { get => UInt16[0x13]; init => UInt16[0x13] = value; }
 
     // Padding at 0x15
 

src/Spice86.Core/Emulator/VM/Machine.cs

@@ -129,6 +129,11 @@ public sealed class Machine : IDisposable, IDebuggableComponent {
     /// </summary>
     public SoundBlaster SoundBlaster { get; }
 
+    /// <summary>
+    /// INT12H handler.
+    /// </summary>
+    public SystemBiosInt12Handler SystemBiosInt12Handler { get; }
+
     /// <summary>
     /// INT15H handler.
     /// </summary>
@@ -200,7 +205,9 @@ public Machine(IGui? gui, State cpuState, IOPortDispatcher ioPortDispatcher, ILo
             Memory.UInt16[0xF000, 0xFFF0] = 0xF4;
         }
         IoPortDispatcher = ioPortDispatcher;
-        BiosDataArea = new BiosDataArea(Memory);
+        BiosDataArea = new BiosDataArea(Memory) {
+            ConventionalMemorySizeKb = (ushort)Math.Clamp(Memory.Ram.Size / 1024, 0, 640) // max 640k conventional memory
+        };
         CpuState = cpuState;
         DualPic = new(CpuState, configuration.FailOnUnhandledPort, configuration.InitializeDOS is false, loggerService);
         // Breakpoints
@@ -265,6 +272,7 @@ public Machine(IGui? gui, State cpuState, IOPortDispatcher ioPortDispatcher, ILo
         BiosKeyboardInt9Handler = new BiosKeyboardInt9Handler(Memory, Cpu, DualPic, Keyboard, BiosDataArea, loggerService);
 
         BiosEquipmentDeterminationInt11Handler = new BiosEquipmentDeterminationInt11Handler(Memory, Cpu, loggerService);
+        SystemBiosInt12Handler = new SystemBiosInt12Handler(Memory, Cpu, BiosDataArea, loggerService);
         SystemBiosInt15Handler = new SystemBiosInt15Handler(Memory, Cpu, Memory.A20Gate, loggerService);
         KeyboardInt16Handler = new KeyboardInt16Handler(Memory, Cpu, loggerService, BiosKeyboardInt9Handler.BiosKeyboardBuffer);
 
@@ -279,6 +287,7 @@ public Machine(IGui? gui, State cpuState, IOPortDispatcher ioPortDispatcher, ILo
             RegisterInterruptHandler(TimerInt8Handler);
             RegisterInterruptHandler(BiosKeyboardInt9Handler);
             RegisterInterruptHandler(BiosEquipmentDeterminationInt11Handler);
+            RegisterInterruptHandler(SystemBiosInt12Handler);
             RegisterInterruptHandler(SystemBiosInt15Handler);
             RegisterInterruptHandler(KeyboardInt16Handler);
             RegisterInterruptHandler(SystemClockInt1AHandler);