diff --git a/M6502/M6502.HarteTest/SingleStepTests.cs b/M6502/M6502.HarteTest/SingleStepTests.cs
index fb3a13f..a91e3fc 100644
--- a/M6502/M6502.HarteTest/SingleStepTests.cs
+++ b/M6502/M6502.HarteTest/SingleStepTests.cs
@@ -91,4 +91,20 @@ namespace M6502.HarteTest
         public async Task OpcodeSingleStep(string filePath)
             => await HarteTestHelper.RunOpcodeAsync(filePath, new TestRunner(r => new WDC65C02(r))).ConfigureAwait(false);
     }
+
+    [TestClass]
+    [System.Diagnostics.CodeAnalysis.SuppressMessage("Maintainability", "CA1515:Consider making public types internal", Justification = "Test class needs to be externally visible")]
+    public class Ricoh2A03SingleStepTests
+    {
+        private const string TestDataDirectory = @"C:\github\spectrum\libraries\EightBit\modules\65x02\nes6502\v1";
+
+        public static IEnumerable<object[]> OpcodeFiles => HarteTestHelper.GetOpcodeFiles(TestDataDirectory);
+
+        public static string GetDisplayName(MethodInfo m, object[] data) => HarteTestHelper.GetDisplayName(m, data);
+
+        [TestMethod]
+        [DynamicData(nameof(OpcodeFiles), DynamicDataSourceType.Property, DynamicDataDisplayName = nameof(GetDisplayName))]
+        public async Task OpcodeSingleStep(string filePath)
+            => await HarteTestHelper.RunOpcodeAsync(filePath, new TestRunner(r => new Ricoh2A03(r))).ConfigureAwait(false);
+    }
 }
diff --git a/M6502/Ricoh2A03.cs b/M6502/Ricoh2A03.cs
new file mode 100644
index 0000000..5c691df
--- /dev/null
+++ b/M6502/Ricoh2A03.cs
@@ -0,0 +1,21 @@
+// <copyright file="Ricoh2A03.cs" company="Adrian Conlon">
+// Copyright (c) Adrian Conlon. All rights reserved.
+// </copyright>
+
+namespace M6502
+{
+    using EightBit;
+
+    public class Ricoh2A03(Bus bus) : MOS6502(bus)
+    {
+        protected override byte DecimalSUB(byte operand, int borrow)
+        {
+            return base.BinarySUB(operand, borrow);
+        }
+
+        protected override byte DecimalADC(byte data)
+        {
+            return base.BinaryADC(data);
+        }
+    }
+}