diff --git a/SabreTools.Serialization/Extensions/NESCart.cs b/SabreTools.Serialization/Extensions/NESCart.cs
index 3be12544..b53e1e85 100644
--- a/SabreTools.Serialization/Extensions/NESCart.cs
+++ b/SabreTools.Serialization/Extensions/NESCart.cs
@@ -165,6 +165,34 @@ namespace SabreTools.Data.Extensions
             };
         }
 
+        /// <summary>
+        /// Convert a <see cref="TVSystem"/> value to string
+        /// </summary>
+        public static string FromTVSystem(this TVSystem system)
+        {
+            return system switch
+            {
+                TVSystem.NTSC => "NTSC",
+                TVSystem.PAL => "PAL",
+                _ => $"Unknown {(byte)system}",
+            };
+        }
+
+         /// <summary>
+        /// Convert a <see cref="TVSystemExtended"/> value to string
+        /// </summary>
+        public static string FromTVSystemExtended(this TVSystemExtended system)
+        {
+            return system switch
+            {
+                TVSystemExtended.NTSC => "NTSC",
+                TVSystemExtended.DualCompatible1 => "Dual-compatible (0x01)",
+                TVSystemExtended.PAL => "PAL",
+                TVSystemExtended.DualCompatible3 => "Dual-compatible (0x03)",
+                _ => $"Unknown {(byte)system}",
+            };
+        }
+
         /// <summary>
         /// Convert a <see cref="VsHardwareType"/> value to string
         /// </summary>
diff --git a/SabreTools.Serialization/Models/NES/Enums.cs b/SabreTools.Serialization/Models/NES/Enums.cs
index aa97467a..f3b568cc 100644
--- a/SabreTools.Serialization/Models/NES/Enums.cs
+++ b/SabreTools.Serialization/Models/NES/Enums.cs
@@ -1,51 +1,5 @@
-using System;
-
 namespace SabreTools.Data.Models.NES
 {
-    /// <summary>
-    /// TV system, PRG-RAM presence (unofficial, rarely used extension)
-    /// </summary>
-    [Flags]
-    public enum Flag10 : byte
-    {
-        #region Bits 0-1
-
-        NTSC = 0b000000,
-        DualCompatible1 = 0b000001,
-        PAL = 0b000010,
-        DualCompatible2 = 0b000011,
-
-        #endregion
-
-        #region Bit 4
-
-        /// <summary>
-        /// PRG RAM ($6000-$7FFF) present
-        /// </summary>
-        PRGRAMPresent = 0b000000,
-
-        /// <summary>
-        /// PRG RAM ($6000-$7FFF) not present
-        /// </summary>
-        PRGRAMNotPresent = 0b010000,
-
-        #endregion
-
-        #region Bit 5
-
-        /// <summary>
-        /// Board has no bus conflicts
-        /// </summary>
-        BoardHasNoBusConflicts = 0b000000,
-
-        /// <summary>
-        /// Board has bus conflicts
-        /// </summary>
-        BoardHasBusConflicts = 0b100000,
-
-        #endregion
-    }
-
     /// <summary>
     /// Console Type
     /// </summary>
@@ -625,12 +579,25 @@ namespace SabreTools.Data.Models.NES
     /// <summary>
     /// TV system (rarely used extension)
     /// </summary>
+    /// <remarks>Byte 9</remarks>
     public enum TVSystem : byte
     {
         NTSC = 0x00,
         PAL = 0x01,
     }
 
+    /// <summary>
+    /// TV system with extended values
+    /// </summary>
+    /// <remarks>Actually only 2 bits (bits 0-1 of flag 10)</remarks>
+    public enum TVSystemExtended : byte
+    {
+        NTSC = 0x00,
+        DualCompatible1 = 0x01,
+        PAL = 0x02,
+        DualCompatible3 = 0x03,
+    }
+
     /// <summary>
     /// Vs. Hardware Type
     /// </summary>
diff --git a/SabreTools.Serialization/Models/NES/Header1.cs b/SabreTools.Serialization/Models/NES/Header1.cs
index a2db94a4..72a78e26 100644
--- a/SabreTools.Serialization/Models/NES/Header1.cs
+++ b/SabreTools.Serialization/Models/NES/Header1.cs
@@ -36,14 +36,64 @@ namespace SabreTools.Data.Models.NES
         /// </remarks>
         public TVSystem TVSystem { get; set; }
 
+        #region Byte 10
+
         /// <summary>
-        /// TV system, PRG-RAM presence (unofficial, rarely used extension)
+        /// TV system with extended values
         /// </summary>
         /// <remarks>
+        /// Byte 10, Bits 0-1
+        ///
         /// This byte is not part of the official specification, and relatively
         /// few emulators honor it.
         /// </remarks>
-        public Flag10 Flag10 { get; set; }
+        public TVSystemExtended TVSystemExtended { get; set; }
+
+        /// <summary>
+        /// Unknown reserved bits
+        /// </summary>
+        /// <remarks>
+        /// Byte 10, Bits 2-3
+        ///
+        /// This byte is not part of the official specification, and relatively
+        /// few emulators honor it.
+        /// </remarks>
+        public byte ReservedBits23 { get; set; }
+
+        /// <summary>
+        /// PRG RAM ($6000-$7FFF) present
+        /// </summary>
+        /// <remarks>
+        /// Byte 10, Bit 4
+        ///
+        /// This byte is not part of the official specification, and relatively
+        /// few emulators honor it.
+        /// </remarks>
+        public bool PRGRAMPresent { get; set; }
+
+        /// <summary>
+        /// Board has bus conflicts
+        /// </summary>
+        /// <remarks>
+        /// Byte 10, Bit 5
+        ///
+        /// This byte is not part of the official specification, and relatively
+        /// few emulators honor it.
+        /// </remarks>
+        public bool HasBusConflicts { get; set; }
+
+        /// <summary>
+        /// Unknown reserved bits
+        /// </summary>
+        /// <remarks>
+        /// Byte 10, Bits 6-7
+        ///
+        /// This byte is not part of the official specification, and relatively
+        /// few emulators honor it.
+        /// </remarks>
+        public byte ReservedBits67 { get; set; }
+
+        #endregion
 
         /// <summary>
         /// Unused padding to align to 16 bytes
diff --git a/SabreTools.Serialization/Readers/NESCart.cs b/SabreTools.Serialization/Readers/NESCart.cs
index 4325857a..cc513d7b 100644
--- a/SabreTools.Serialization/Readers/NESCart.cs
+++ b/SabreTools.Serialization/Readers/NESCart.cs
@@ -93,17 +93,17 @@ namespace SabreTools.Serialization.Readers
             byte prgRomSize = data.ReadByteValue();
             byte chrRomSize = data.ReadByteValue();
 
-            byte flag6 = data.ReadByteValue();
-            NametableArrangement nametableArrangement = (NametableArrangement)(flag6 & 0x01);
-            bool batteryBackedPrgRam = ((flag6 >> 1) & 0x01) != 0;
-            bool trainerPresent = ((flag6 >> 2) & 0x01) != 0;
-            bool alternativeNametableLayout = ((flag6 >> 3) & 0x01) != 0;
-            byte mapperLowerNibble = (byte)(flag6 >> 4);
+            byte byte6 = data.ReadByteValue();
+            NametableArrangement nametableArrangement = (NametableArrangement)(byte6 & 0x01);
+            bool batteryBackedPrgRam = ((byte6 >> 1) & 0x01) != 0;
+            bool trainerPresent = ((byte6 >> 2) & 0x01) != 0;
+            bool alternativeNametableLayout = ((byte6 >> 3) & 0x01) != 0;
+            byte mapperLowerNibble = (byte)(byte6 >> 4);
 
-            byte flag7 = data.ReadByteValue();
-            ConsoleType consoleType = (ConsoleType)(flag7 & 0x03);
-            bool nes20 = ((flag7 >> 2) & 0x02) == 0x02;
-            byte mapperUpperNibble = (byte)(flag7 >> 4);
+            byte byte7 = data.ReadByteValue();
+            ConsoleType consoleType = (ConsoleType)(byte7 & 0x03);
+            bool nes20 = ((byte7 >> 2) & 0x02) == 0x02;
+            byte mapperUpperNibble = (byte)(byte7 >> 4);
 
             // NES 2.0
             if (nes20)
@@ -147,21 +147,29 @@ namespace SabreTools.Serialization.Readers
                 obj.PRGROMSize = prgRomSize;
                 obj.CHRROMSize = chrRomSize;
 
-                // Flag 6
+                // Byte 6
                 obj.NametableArrangement = nametableArrangement;
                 obj.BatteryBackedPRGRAM = batteryBackedPrgRam;
                 obj.TrainerPresent = trainerPresent;
                 obj.AlternativeNametableLayout = alternativeNametableLayout;
                 obj.MapperLowerNibble = mapperLowerNibble;
 
-                // Flag 7
+                // Byte 7
                 obj.ConsoleType = consoleType;
                 obj.NES20 = nes20;
                 obj.MapperUpperNibble = mapperUpperNibble;
 
                 obj.PRGRAMSize = data.ReadByteValue();
                 obj.TVSystem = (TVSystem)data.ReadByteValue();
-                obj.Flag10 = (Flag10)data.ReadByteValue();
+
+                // Byte 10
+                byte byte10 = data.ReadByteValue();
+                obj.TVSystemExtended = (TVSystemExtended)(byte10 & 0x03);
+                obj.ReservedBits23 = (byte)((byte10 >> 2) & 0x03);
+                obj.PRGRAMPresent = ((byte10 >> 4) & 0x01) == 0x01;
+                obj.HasBusConflicts = ((byte10 >> 5) & 0x01) == 0x01;
+                obj.ReservedBits67 = (byte)((byte10 >> 6) & 0x03);
+
                 obj.Padding = data.ReadBytes(5);
 
                 return obj;
diff --git a/SabreTools.Serialization/Wrappers/NESCart.Printing.cs b/SabreTools.Serialization/Wrappers/NESCart.Printing.cs
index d3418cc0..40a6eeed 100644
--- a/SabreTools.Serialization/Wrappers/NESCart.Printing.cs
+++ b/SabreTools.Serialization/Wrappers/NESCart.Printing.cs
@@ -91,7 +91,8 @@ namespace SabreTools.Serialization.Wrappers
                 builder.AppendLine(header1.PRGRAMSize, prefixString: "  PRG-RAM size in 8KiB units");
 
                 // Byte 9
-                builder.AppendLine($"  TV system: {header1.TVSystem} (0x{header1.TVSystem:X})");
+                string tvSystem = header1.TVSystem.FromTVSystem();
+                builder.AppendLine(tvSystem, "  TV system");
 
                 // Byte 10
                 #region Flag 10
@@ -99,46 +100,21 @@ namespace SabreTools.Serialization.Wrappers
                 builder.AppendLine("  Flag 10:");
 
                 // Bits 0-1
-#if NET20 || NET35
-                if ((header1.Flag10 & Flag10.DualCompatible2) != 0)
-#else
-                if (header1.Flag10.HasFlag(Flag10.DualCompatible2))
-#endif
-                    builder.AppendLine("    TV System: Dual-compatible");
-#if NET20 || NET35
-                else if ((header1.Flag10 & Flag10.PAL) != 0)
-#else
-                else if (header1.Flag10.HasFlag(Flag10.PAL))
-#endif
-                    builder.AppendLine("    TV System: PAL");
-#if NET20 || NET35
-                else if ((header1.Flag10 & Flag10.DualCompatible1) != 0)
-#else
-                else if (header1.Flag10.HasFlag(Flag10.DualCompatible1))
-#endif
-                    builder.AppendLine("    TV System: Dual-compatible");
-                else
-                    builder.AppendLine("    TV System: NTSC");
+                string tvSystemExtended = header1.TVSystemExtended.FromTVSystemExtended();
+                builder.AppendLine(tvSystemExtended, "    TV System Extended");
+
+                // Bits 2-3
+                builder.AppendLine(header1.ReservedBits23, "    Reserved bits 1-2");
 
                 // Bit 4
-#if NET20 || NET35
-                if ((header1.Flag10 & Flag10.PRGRAMNotPresent) != 0)
-#else
-                if (header1.Flag10.HasFlag(Flag10.PRGRAMNotPresent))
-#endif
-                    builder.AppendLine("    PRG-RAM: Not present");
-                else
-                    builder.AppendLine("    PRG-RAM: Present");
+                string prgRamPresent = header1.PRGRAMPresent ? "Present" : "Not present";
+                builder.AppendLine(prgRamPresent, "    PRG-RAM");
 
                 // Bit 5
-#if NET20 || NET35
-                if ((header1.Flag10 & Flag10.BoardHasBusConflicts) != 0)
-#else
-                if (header1.Flag10.HasFlag(Flag10.BoardHasBusConflicts))
-#endif
-                    builder.AppendLine("    Has Bus Conflicts: True");
-                else
-                    builder.AppendLine("    Has Bus Conflicts: False");
+                builder.AppendLine(header1.HasBusConflicts, "    Has Bus Conflicts");
+
+                // Bits 6-7
+                builder.AppendLine(header1.ReservedBits67, "    Reserved bits 6-7");
 
                 #endregion
 
diff --git a/SabreTools.Serialization/Wrappers/NESCart.cs b/SabreTools.Serialization/Wrappers/NESCart.cs
index f52e1164..d7046889 100644
--- a/SabreTools.Serialization/Wrappers/NESCart.cs
+++ b/SabreTools.Serialization/Wrappers/NESCart.cs
@@ -147,9 +147,7 @@ namespace SabreTools.Serialization.Wrappers
 
         #region NES 1.0
 
-        /// <summary>
-        /// Indicates if the board has bus conflicts
-        /// </summary>
+        /// <inheritdoc cref="Header1.HasBusConflicts"/>
         /// <remarks>Defined only for NES 1.0</remarks>
         public bool HasBusConflicts
         {
@@ -159,19 +157,13 @@ namespace SabreTools.Serialization.Wrappers
                 if (Header is null || Header is not Header1 header1)
                     return false;
 
-#if NET20 || NET35
-                return (header1.Flag10 & Flag10.BoardHasBusConflicts) != 0;
-#else
-                return header1.Flag10.HasFlag(Flag10.BoardHasBusConflicts);
-#endif
+                return header1.HasBusConflicts;
             }
         }
 
-        /// <summary>
-        /// Indicates if PRG RAM at $6000-$7FFF is present
-        /// </summary>
+        /// <inheritdoc cref="Header1.PRGRAMPresent"/>
         /// <remarks>Defined only for NES 1.0</remarks>
-        public bool HasPRGRAM
+        public bool PRGRAMPresent
         {
             get
             {
@@ -179,11 +171,35 @@ namespace SabreTools.Serialization.Wrappers
                 if (Header is null || Header is not Header1 header1)
                     return false;
 
-#if NET20 || NET35
-                return (header1.Flag10 & Flag10.PRGRAMNotPresent) == 0;
-#else
-                return !header1.Flag10.HasFlag(Flag10.PRGRAMNotPresent);
-#endif
+                return header1.PRGRAMPresent;
+            }
+        }
+
+        /// <inheritdoc cref="Header1.TVSystem"/>
+        /// <remarks>Defined only for NES 1.0</remarks>
+        public TVSystem TVSystem
+        {
+            get
+            {
+                // Missing or invalid header
+                if (Header is null || Header is not Header1 header1)
+                    return TVSystem.NTSC;
+
+                return header1.TVSystem;
+            }
+        }
+
+        /// <inheritdoc cref="Header1.TVSystemExtended"/>
+        /// <remarks>Defined only for NES 1.0</remarks>
+        public TVSystemExtended TVSystemExtended
+        {
+            get
+            {
+                // Missing or invalid header
+                if (Header is null || Header is not Header1 header1)
+                    return TVSystemExtended.NTSC;
+
+                return header1.TVSystemExtended;
             }
         }