diff --git a/Core/Core.vcxproj b/Core/Core.vcxproj
index 5c07e62d..975b59ea 100644
--- a/Core/Core.vcxproj
+++ b/Core/Core.vcxproj
@@ -444,6 +444,7 @@
     <ClInclude Include="Mapper230.h" />
     <ClInclude Include="Mapper241.h" />
     <ClInclude Include="Mapper40.h" />
+    <ClInclude Include="Mapper42.h" />
     <ClInclude Include="Mapper50.h" />
     <ClInclude Include="Mapper60.h" />
     <ClInclude Include="MMC1_155.h" />
diff --git a/Core/Core.vcxproj.filters b/Core/Core.vcxproj.filters
index 49d6ec98..60345255 100644
--- a/Core/Core.vcxproj.filters
+++ b/Core/Core.vcxproj.filters
@@ -703,6 +703,9 @@
     <ClInclude Include="Mapper50.h">
       <Filter>Nes\Mappers\Unnamed</Filter>
     </ClInclude>
+    <ClInclude Include="Mapper42.h">
+      <Filter>Nes\Mappers\Unnamed</Filter>
+    </ClInclude>
   </ItemGroup>
   <ItemGroup>
     <ClCompile Include="stdafx.cpp">
diff --git a/Core/Mapper42.h b/Core/Mapper42.h
new file mode 100644
index 00000000..2c51ca92
--- /dev/null
+++ b/Core/Mapper42.h
@@ -0,0 +1,76 @@
+#pragma once
+#include "stdafx.h"
+#include "BaseMapper.h"
+#include "CPU.h"
+
+class Mapper42 : public BaseMapper
+{
+private:
+	uint16_t _irqCounter;
+	bool _irqEnabled;
+
+protected:
+	virtual uint16_t GetPRGPageSize() { return 0x2000; }
+	virtual uint16_t GetCHRPageSize() { return 0x2000; }
+
+	void InitMapper()
+	{
+		_irqCounter = 0;
+		_irqEnabled = false;
+
+		SelectPRGPage(0, 0x0C);
+		SelectPRGPage(1, 0x0D);
+		SelectPRGPage(2, 0x0E);
+		SelectPRGPage(3, 0x0F);
+		SelectCHRPage(0, 0);
+	}
+
+	void StreamState(bool saving)
+	{
+		BaseMapper::StreamState(saving);
+		Stream(_irqCounter, _irqEnabled);
+	}
+
+	void ProcessCpuClock()
+	{
+		if(_irqEnabled) {
+			_irqCounter++;
+			if(_irqCounter >= 0x8000) {
+				_irqCounter -= 0x8000;
+			}
+			if(_irqCounter >= 0x6000) {
+				CPU::SetIRQSource(IRQSource::External);
+			} else {
+				CPU::ClearIRQSource(IRQSource::External);
+			}
+		}
+	}
+
+	void WriteRegister(uint16_t addr, uint8_t value)
+	{
+		switch(addr & 0xE003) {
+			case 0x8000:
+				if(_chrRomSize > 0) {
+					SelectCHRPage(0, value & 0x0F);
+				}
+				break;
+
+			case 0xE000:
+				SetCpuMemoryMapping(0x6000, 0x7FFF, value & 0x0F, PrgMemoryType::PrgRom);
+				break;
+
+			case 0xE001:
+				SetMirroringType(value & 0x08 ? MirroringType::Horizontal : MirroringType::Vertical);
+				break;
+
+			case 0xE002:
+				_irqEnabled = (value == 0x02);
+
+				if(!_irqEnabled) {
+					CPU::ClearIRQSource(IRQSource::External);
+					_irqCounter = 0;
+				}
+				break;
+		}
+	}
+};
diff --git a/Core/MapperFactory.cpp b/Core/MapperFactory.cpp
index d1eef048..64a6708c 100644
--- a/Core/MapperFactory.cpp
+++ b/Core/MapperFactory.cpp
@@ -28,6 +28,7 @@
 #include "JalecoSs88006.h"
 #include "Mapper15.h"
 #include "Mapper40.h"
+#include "Mapper42.h"
 #include "Mapper50.h"
 #include "Mapper57.h"
 #include "Mapper58.h"
@@ -118,7 +119,7 @@ Supported mappers:  (... denotes bad mappers)
 -----------------------------------------------------------------
 | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10| 11| 12| 13|   | 15|
 | 16| 17| 18| 19|...| 21| 22| 23| 24| 25| 26| 27|   |   |   | 31|
-| 32| 33| 34|   |   | 37| 38|   | 40|   |   |   | 44| 45|   | 47|
+| 32| 33| 34|   |   | 37| 38|   | 40|   | 42|   | 44| 45|   | 47|
 |   | 49| 50|   | 52|   |   |   |   | 57| 58|   | 60| 61| 62|   |
 | 64| 65| 66| 67| 68| 69| 70| 71| 72| 73| 74| 75| 76| 77| 78| 79|
 | 80|   | 82|   |   | 85| 86| 87| 88| 89|   | 91| 92| 93| 94| 95|
@@ -183,6 +184,7 @@ BaseMapper* MapperFactory::GetMapperFromID(RomData &romData)
 		case 37: return new MMC3_37();
 		case 38: return new UnlPci556();
 		case 40: return new Mapper40();
+		case 42: return new Mapper42();
 		case 44: return new MMC3_44();
 		case 45: return new MMC3_45();
 		case 47: return new MMC3_47();