diff --git a/src/Chip8.Core/FontSet.cs b/src/Chip8.Core/FontSet.cs
new file mode 100644
index 0000000..4a108be
--- /dev/null
+++ b/src/Chip8.Core/FontSet.cs
@@ -0,0 +1,48 @@
+namespace Chip8.Core;
+
+internal static class FontSet
+{
+    public const int glyphBytes = 5;
+
+    public const int bigGlyphBytes = 10;
+
+    public static readonly byte[] glyphs =
+    {
+        0xF0, 0x90, 0x90, 0x90, 0xF0, // 0
+        0x20, 0x60, 0x20, 0x20, 0x70, // 1
+        0xF0, 0x10, 0xF0, 0x80, 0xF0, // 2
+        0xF0, 0x10, 0xF0, 0x10, 0xF0, // 3
+        0x90, 0x90, 0xF0, 0x10, 0x10, // 4
+        0xF0, 0x80, 0xF0, 0x10, 0xF0, // 5
+        0xF0, 0x80, 0xF0, 0x90, 0xF0, // 6
+        0xF0, 0x10, 0x20, 0x40, 0x40, // 7
+        0xF0, 0x90, 0xF0, 0x90, 0xF0, // 8
+        0xF0, 0x90, 0xF0, 0x10, 0xF0, // 9
+        0xF0, 0x90, 0xF0, 0x90, 0x90, // A
+        0xE0, 0x90, 0xE0, 0x90, 0xE0, // B
+        0xF0, 0x80, 0x80, 0x80, 0xF0, // C
+        0xE0, 0x90, 0x90, 0x90, 0xE0, // D
+        0xF0, 0x80, 0xF0, 0x80, 0xF0, // E
+        0xF0, 0x80, 0xF0, 0x80, 0x80, // F
+    };
+
+    public static readonly byte[] bigGlyphs =
+    {
+        0x3C, 0x7E, 0xE7, 0xC3, 0xC3, 0xC3, 0xC3, 0xE7, 0x7E, 0x3C, // 0
+        0x18, 0x38, 0x58, 0x18, 0x18, 0x18, 0x18, 0x18, 0x18, 0x3C, // 1
+        0x3E, 0x7F, 0xC3, 0x06, 0x0C, 0x18, 0x30, 0x60, 0xFF, 0xFF, // 2
+        0x3C, 0x7E, 0xC3, 0x03, 0x0E, 0x0E, 0x03, 0xC3, 0x7E, 0x3C, // 3
+        0x06, 0x0E, 0x1E, 0x36, 0x66, 0xC6, 0xFF, 0xFF, 0x06, 0x06, // 4
+        0xFF, 0xFF, 0xC0, 0xC0, 0xFC, 0xFE, 0x03, 0xC3, 0x7E, 0x3C, // 5
+        0x3E, 0x7C, 0xE0, 0xC0, 0xFC, 0xFE, 0xC3, 0xC3, 0x7E, 0x3C, // 6
+        0xFF, 0xFF, 0x03, 0x06, 0x0C, 0x18, 0x30, 0x60, 0x60, 0x60, // 7
+        0x3C, 0x7E, 0xC3, 0xC3, 0x7E, 0x7E, 0xC3, 0xC3, 0x7E, 0x3C, // 8
+        0x3C, 0x7E, 0xC3, 0xC3, 0x7F, 0x3F, 0x03, 0x07, 0x7E, 0x7C, // 9
+        0x18, 0x3C, 0x66, 0xC3, 0xC3, 0xFF, 0xFF, 0xC3, 0xC3, 0xC3, // A
+        0xFC, 0xFE, 0xC3, 0xC3, 0xFE, 0xFE, 0xC3, 0xC3, 0xFE, 0xFC, // B
+        0x3C, 0x7E, 0xC3, 0xC0, 0xC0, 0xC0, 0xC0, 0xC3, 0x7E, 0x3C, // C
+        0xFC, 0xFE, 0xC3, 0xC3, 0xC3, 0xC3, 0xC3, 0xC3, 0xFE, 0xFC, // D
+        0xFF, 0xFF, 0xC0, 0xC0, 0xFC, 0xFC, 0xC0, 0xC0, 0xFF, 0xFF, // E
+        0xFF, 0xFF, 0xC0, 0xC0, 0xFC, 0xFC, 0xC0, 0xC0, 0xC0, 0xC0, // F
+    };
+}
diff --git a/src/Chip8.Core/MachineSnapshot.cs b/src/Chip8.Core/MachineSnapshot.cs
new file mode 100644
index 0000000..7ce649e
--- /dev/null
+++ b/src/Chip8.Core/MachineSnapshot.cs
@@ -0,0 +1,71 @@
+using System;
+using System.Globalization;
+using System.Text;
+
+namespace Chip8.Core;
+
+public sealed class MachineSnapshot
+{
+    public ushort pc { get; init; }
+    public ushort i { get; init; }
+    public byte sp { get; init; }
+    public byte delayTimer { get; init; }
+    public byte soundTimer { get; init; }
+    public int planeMask { get; init; }
+    public bool hires { get; init; }
+    public bool exited { get; init; }
+    public byte[] v { get; init; } = Array.Empty<byte>();
+    public ushort[] stack { get; init; } = Array.Empty<ushort>();
+
+    public static MachineSnapshot capture(Machine machine)
+    {
+        var stackFrames = new ushort[machine.sp];
+        Array.Copy(machine.stack, stackFrames, machine.sp);
+        return new MachineSnapshot
+        {
+            pc = machine.pc,
+            i = machine.i,
+            sp = machine.sp,
+            delayTimer = machine.delayTimer,
+            soundTimer = machine.soundTimer,
+            planeMask = machine.planeMask,
+            hires = machine.hires,
+            exited = machine.exited,
+            v = (byte[])machine.v.Clone(),
+            stack = stackFrames,
+        };
+    }
+
+    public string format()
+    {
+        var builder = new StringBuilder();
+        builder.Append("PC=0x").Append(pc.ToString("X4", CultureInfo.InvariantCulture));
+        builder.Append(" I=0x").Append(i.ToString("X4", CultureInfo.InvariantCulture));
+        builder.Append(" SP=").Append(sp);
+        builder.Append(" DT=").Append(delayTimer);
+        builder.Append(" ST=").Append(soundTimer);
+        builder.Append(" plane=").Append(planeMask);
+        builder.Append(" hires=").Append(hires ? "1" : "0");
+        builder.Append('\n');
+
+        for (int register = 0; register < v.Length; register++)
+        {
+            builder.Append('V').Append(register.ToString("X1", CultureInfo.InvariantCulture));
+            builder.Append('=').Append(v[register].ToString("X2", CultureInfo.InvariantCulture));
+            builder.Append((register & 0x7) == 0x7 ? '\n' : ' ');
+        }
+
+        builder.Append("stack=[");
+        for (int frame = 0; frame < stack.Length; frame++)
+        {
+            if (frame > 0)
+            {
+                builder.Append(' ');
+            }
+            builder.Append("0x").Append(stack[frame].ToString("X4", CultureInfo.InvariantCulture));
+        }
+        builder.Append("]\n");
+
+        return builder.ToString();
+    }
+}
diff --git a/src/Chip8.Core/Quirks.cs b/src/Chip8.Core/Quirks.cs
new file mode 100644
index 0000000..1b3e84c
--- /dev/null
+++ b/src/Chip8.Core/Quirks.cs
@@ -0,0 +1,56 @@
+namespace Chip8.Core;
+
+public sealed class Quirks
+{
+    public bool shiftUsesVy { get; set; }
+
+    public bool jumpWithVx { get; set; }
+
+    public bool loadStoreIncrementsI { get; set; }
+
+    public bool resetVfOnLogic { get; set; }
+
+    public bool clipSprites { get; set; }
+
+    public bool addToIndexSetsCarry { get; set; }
+
+    public static Quirks cosmacVip() => new()
+    {
+        shiftUsesVy = true,
+        jumpWithVx = false,
+        loadStoreIncrementsI = true,
+        resetVfOnLogic = true,
+        clipSprites = true,
+        addToIndexSetsCarry = false,
+    };
+
+    public static Quirks modern() => new()
+    {
+        shiftUsesVy = false,
+        jumpWithVx = false,
+        loadStoreIncrementsI = false,
+        resetVfOnLogic = false,
+        clipSprites = true,
+        addToIndexSetsCarry = false,
+    };
+
+    public static Quirks superChip() => new()
+    {
+        shiftUsesVy = false,
+        jumpWithVx = true,
+        loadStoreIncrementsI = false,
+        resetVfOnLogic = false,
+        clipSprites = true,
+        addToIndexSetsCarry = false,
+    };
+
+    public static Quirks xoChip() => new()
+    {
+        shiftUsesVy = false,
+        jumpWithVx = false,
+        loadStoreIncrementsI = false,
+        resetVfOnLogic = false,
+        clipSprites = false,
+        addToIndexSetsCarry = false,
+    };
+}