Update to clarify that INT12 only reports on the first 640k conventio…

…nal memory
JorisVanEijden · Jan 23, 2024 · ed1c233 · ed1c233
1 parent ca27cbb
commit ed1c233
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Showing 3 changed files with 6 additions and 3 deletions.
diff --git a/src/Spice86.Core/Emulator/InterruptHandlers/Bios/SystemBiosInt12Handler.cs b/src/Spice86.Core/Emulator/InterruptHandlers/Bios/SystemBiosInt12Handler.cs
@@ -26,6 +26,6 @@ public SystemBiosInt12Handler(IMemory memory, Cpu cpu, BiosDataArea biosDataArea
 
  /// <inheritdoc />
  public override void Run() {
- _state.AX = _biosDataArea.MemSizeKb;
+ _state.AX = _biosDataArea.ConventionalMemorySizeKb;
  }
 }
diff --git a/src/Spice86.Core/Emulator/Memory/BiosDataArea.cs b/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
 

diff --git a/src/Spice86.Core/Emulator/VM/Machine.cs b/src/Spice86.Core/Emulator/VM/Machine.cs
@@ -206,7 +206,7 @@ public Machine(IGui? gui, State cpuState, IOPortDispatcher ioPortDispatcher, ILo
  }
  IoPortDispatcher = ioPortDispatcher;
  BiosDataArea = new BiosDataArea(Memory) {
- MemSizeKb = (ushort)Math.Clamp(Memory.Ram.Size / 1024, 0, 1024) // max 1mb.
+ 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);