diff --git a/tests/Chip8.Tests/XoChipTests.cs b/tests/Chip8.Tests/XoChipTests.cs
new file mode 100644
index 0000000..2cbd7d9
--- /dev/null
+++ b/tests/Chip8.Tests/XoChipTests.cs
@@ -0,0 +1,170 @@
+using System;
+using Chip8.Core;
+using Xunit;
+
+namespace Chip8.Tests;
+
+public class XoChipTests
+{
+    [Fact]
+    public void planeSelectStoresMask()
+    {
+        var machine = TestHarness.withOpcode(0xF201, Platform.XoChip);
+        machine.step();
+        Assert.Equal(2, machine.planeMask);
+    }
+
+    [Fact]
+    public void drawToSecondPlaneProducesColorTwo()
+    {
+        var machine = TestHarness.withProgram(Platform.XoChip, 0xF201, 0xD011);
+        machine.i = 0x300;
+        machine.memory[0x300] = 0x80;
+        machine.step();
+        machine.step();
+        Assert.Equal(2, machine.video.colorAt(0, 0));
+    }
+
+    [Fact]
+    public void drawToBothPlanesProducesColorThree()
+    {
+        var machine = TestHarness.withProgram(Platform.XoChip, 0xF301, 0xD011);
+        machine.i = 0x300;
+        machine.memory[0x300] = 0x80;
+        machine.memory[0x301] = 0x80;
+        machine.step();
+        machine.step();
+        Assert.Equal(3, machine.video.colorAt(0, 0));
+        Assert.Equal(0, machine.video.colorAt(1, 0));
+    }
+
+    [Fact]
+    public void clearAffectsOnlySelectedPlane()
+    {
+        var machine = TestHarness.withProgram(Platform.XoChip, 0xF301, 0xD011, 0xF101, 0x00E0);
+        machine.i = 0x300;
+        machine.memory[0x300] = 0x80;
+        machine.memory[0x301] = 0x80;
+        machine.step();
+        machine.step();
+        machine.step();
+        machine.step();
+        Assert.Equal(2, machine.video.colorAt(0, 0));
+    }
+
+    [Fact]
+    public void longLoadSetsIndexToSixteenBitAddress()
+    {
+        var machine = TestHarness.withProgram(Platform.XoChip, 0xF000, 0x1234);
+        machine.step();
+        Assert.Equal(0x1234, machine.i);
+        Assert.Equal(0x204, machine.pc);
+    }
+
+    [Fact]
+    public void takenSkipJumpsOverLongLoad()
+    {
+        var machine = TestHarness.withProgram(Platform.XoChip, 0x3000, 0xF000, 0x1234, 0x00E0);
+        machine.step();
+        Assert.Equal(0x206, machine.pc);
+    }
+
+    [Fact]
+    public void takenSkipOverNormalInstructionAdvancesTwo()
+    {
+        var machine = TestHarness.withProgram(Platform.XoChip, 0x3000, 0x6042);
+        machine.step();
+        Assert.Equal(0x204, machine.pc);
+    }
+
+    [Fact]
+    public void storeAndLoadRegisterRange()
+    {
+        var machine = TestHarness.withProgram(Platform.XoChip, 0x5132, 0x5463);
+        machine.i = 0x400;
+        machine.v[1] = 0xAA;
+        machine.v[2] = 0xBB;
+        machine.v[3] = 0xCC;
+
+        machine.step();
+        Assert.Equal(0xAA, machine.memory[0x400]);
+        Assert.Equal(0xBB, machine.memory[0x401]);
+        Assert.Equal(0xCC, machine.memory[0x402]);
+        Assert.Equal(0x400, machine.i);
+
+        machine.step();
+        Assert.Equal(0xAA, machine.v[4]);
+        Assert.Equal(0xBB, machine.v[5]);
+        Assert.Equal(0xCC, machine.v[6]);
+    }
+
+    [Fact]
+    public void storeRangeInReverseOrder()
+    {
+        var machine = TestHarness.withProgram(Platform.XoChip, 0x5312);
+        machine.i = 0x400;
+        machine.v[1] = 0x11;
+        machine.v[2] = 0x22;
+        machine.v[3] = 0x33;
+
+        machine.step();
+
+        Assert.Equal(0x33, machine.memory[0x400]);
+        Assert.Equal(0x22, machine.memory[0x401]);
+        Assert.Equal(0x11, machine.memory[0x402]);
+    }
+
+    [Fact]
+    public void audioPatternBufferLoadsFromMemory()
+    {
+        var machine = TestHarness.withProgram(Platform.XoChip, 0xF002);
+        machine.i = 0x400;
+        for (int offset = 0; offset < 16; offset++)
+        {
+            machine.memory[0x400 + offset] = (byte)offset;
+        }
+
+        machine.step();
+
+        Assert.Equal(0, machine.audioPattern[0]);
+        Assert.Equal(15, machine.audioPattern[15]);
+    }
+
+    [Fact]
+    public void pitchSetsPlaybackFrequency()
+    {
+        var machine = TestHarness.withOpcode(0xF03A, Platform.XoChip);
+        machine.v[0] = 112;
+        machine.step();
+        Assert.Equal(112, machine.audioPitch);
+        Assert.True(Math.Abs(machine.audioFrequency - 8000.0) < 0.001);
+    }
+
+    [Fact]
+    public void extendedMemoryIsSixtyFourKilobytes()
+    {
+        var machine = new Machine(null, 1, Platform.XoChip);
+        Assert.Equal(65536, machine.memory.Length);
+
+        var rom = new byte[5000];
+        rom[0] = 0xAB;
+        rom[4999] = 0xCD;
+        machine.loadRom(rom);
+        Assert.Equal(0xAB, machine.memory[0x200]);
+        Assert.Equal(0xCD, machine.memory[0x200 + 4999]);
+    }
+
+    [Fact]
+    public void scrollUpOpcodeMovesContent()
+    {
+        var machine = TestHarness.withProgram(Platform.XoChip, 0x00D4);
+        machine.memory[0x300] = 0x80;
+        machine.video.drawSprite(machine.memory, 0x300, 5, 10, 1, 1, false);
+        Assert.True(machine.video.pixel(0, 5, 10));
+
+        machine.step();
+
+        Assert.False(machine.video.pixel(0, 5, 10));
+        Assert.True(machine.video.pixel(0, 5, 6));
+    }
+}