diff --git a/SabreTools.DatFiles/Formats/OpenMSX.Reader.cs b/SabreTools.DatFiles/Formats/OpenMSX.Reader.cs
index df9b7dcc..86d217e4 100644
--- a/SabreTools.DatFiles/Formats/OpenMSX.Reader.cs
+++ b/SabreTools.DatFiles/Formats/OpenMSX.Reader.cs
@@ -1,6 +1,7 @@
 using System;
 using System.Linq;
 using SabreTools.Core;
+using SabreTools.Core.Tools;
 using SabreTools.DatItems;
 using SabreTools.DatItems.Formats;
 
@@ -159,7 +160,7 @@ namespace SabreTools.DatFiles.Formats
                 {
                     item.Original = new Original
                     {
-                        Value = dump.Original.Value,
+                        Value = dump.Original.Value.AsYesNo(),
                         Content = dump.Original.Content,
                     };
                 }
diff --git a/SabreTools.DatFiles/Formats/OpenMSX.Writer.cs b/SabreTools.DatFiles/Formats/OpenMSX.Writer.cs
index f5d5a6d9..c36217c8 100644
--- a/SabreTools.DatFiles/Formats/OpenMSX.Writer.cs
+++ b/SabreTools.DatFiles/Formats/OpenMSX.Writer.cs
@@ -1,13 +1,9 @@
 using System;
 using System.Collections.Generic;
-using System.IO;
-using System.Text;
-using System.Xml;
+using System.Linq;
 using SabreTools.Core;
-using SabreTools.Core.Tools;
 using SabreTools.DatItems;
 using SabreTools.DatItems.Formats;
-using SabreTools.IO;
 
 namespace SabreTools.DatFiles.Formats
 {
@@ -28,8 +24,20 @@ namespace SabreTools.DatFiles.Formats
         /// <inheritdoc/>
         protected override List<DatItemField> GetMissingRequiredFields(DatItem datItem)
         {
-            // TODO: Check required fields
-            return null;
+            var missingFields = new List<DatItemField>();
+
+            if (string.IsNullOrWhiteSpace(datItem.GetName()))
+                missingFields.Add(DatItemField.Name);
+
+            switch (datItem)
+            {
+                case Rom rom:
+                    if (string.IsNullOrWhiteSpace(rom.SHA1))
+                        missingFields.Add(DatItemField.SHA1);
+                    break;
+            }
+
+            return missingFields;
         }
 
         /// <inheritdoc/>
@@ -38,70 +46,14 @@ namespace SabreTools.DatFiles.Formats
             try
             {
                 logger.User($"Writing to '{outfile}'...");
-                FileStream fs = System.IO.File.Create(outfile);
 
-                // If we get back null for some reason, just log and return
-                if (fs == null)
+                // TODO: Write out comment prefix somehow
+                var softwaredb = CreateSoftwareDb(ignoreblanks);
+                if (!Serialization.OpenMSX.SerializeToFileWithDocType(softwaredb, outfile))
                 {
-                    logger.Warning($"File '{outfile}' could not be created for writing! Please check to see if the file is writable");
+                    logger.Warning($"File '{outfile}' could not be written! See the log for more details.");
                     return false;
                 }
-
-                XmlTextWriter xtw = new(fs, new UTF8Encoding(false))
-                {
-                    Formatting = Formatting.Indented,
-                    IndentChar = '\t',
-                    Indentation = 1
-                };
-
-                // Write out the header
-                WriteHeader(xtw);
-
-                // Write out each of the machines and roms
-                string lastgame = null;
-
-                // Use a sorted list of games to output
-                foreach (string key in Items.SortedKeys)
-                {
-                    ConcurrentList<DatItem> datItems = Items.FilteredItems(key);
-
-                    // If this machine doesn't contain any writable items, skip
-                    if (!ContainsWritable(datItems))
-                        continue;
-
-                    // Resolve the names in the block
-                    datItems = DatItem.ResolveNames(datItems);
-
-                    for (int index = 0; index < datItems.Count; index++)
-                    {
-                        DatItem datItem = datItems[index];
-
-                        // If we have a different game and we're not at the start of the list, output the end of last item
-                        if (lastgame != null && lastgame.ToLowerInvariant() != datItem.Machine.Name.ToLowerInvariant())
-                            WriteEndGame(xtw);
-
-                        // If we have a new game, output the beginning of the new item
-                        if (lastgame == null || lastgame.ToLowerInvariant() != datItem.Machine.Name.ToLowerInvariant())
-                            WriteStartGame(xtw, datItem);
-
-                        // Check for a "null" item
-                        datItem = ProcessNullifiedItem(datItem);
-
-                        // Write out the item if we're not ignoring
-                        if (!ShouldIgnore(datItem, ignoreblanks))
-                            WriteDatItem(xtw, datItem);
-
-                        // Set the new data to compare against
-                        lastgame = datItem.Machine.Name;
-                    }
-                }
-
-                // Write the file footer out
-                WriteFooter(xtw);
-
-                logger.User($"'{outfile}' written!{Environment.NewLine}");
-                xtw.Dispose();
-                fs.Dispose();
             }
             catch (Exception ex) when (!throwOnError)
             {
@@ -109,149 +61,124 @@ namespace SabreTools.DatFiles.Formats
                 return false;
             }
 
+            logger.User($"'{outfile}' written!{Environment.NewLine}");
             return true;
         }
 
-        /// <summary>
-        /// Write out DAT header using the supplied StreamWriter
-        /// </summary>
-        /// <param name="xtw">XmlTextWriter to output to</param>
-        private void WriteHeader(XmlTextWriter xtw)
-        {
-            xtw.WriteStartDocument();
-            xtw.WriteDocType("softwaredb", null, "softwaredb1.dtd", null);
-
-            xtw.WriteStartElement("softwaredb");
-            xtw.WriteRequiredAttributeString("timestamp", Header.Date);
-
-            //TODO: Figure out how to fix the issue with removed formatting after this point
-//                xtw.WriteComment("Credits");
-//                xtw.WriteCData(@"The softwaredb.xml file contains information about rom mapper types
-
-//-Copyright 2003 Nicolas Beyaert(Initial Database)
-//-Copyright 2004 - 2013 BlueMSX Team
-//-Copyright 2005 - 2020 openMSX Team
-//-Generation MSXIDs by www.generation - msx.nl
-
-//- Thanks go out to:
-//-Generation MSX / Sylvester for the incredible source of information
-//- p_gimeno and diedel for their help adding and valdiating ROM additions
-//- GDX for additional ROM info and validations and corrections");
-
-            xtw.Flush();
-        }
+        #region Converters
 
         /// <summary>
-        /// Write out Game start using the supplied StreamWriter
-        /// </summary>
-        /// <param name="xtw">XmlTextWriter to output to</param>
-        /// <param name="datItem">DatItem object to be output</param>
-        private void WriteStartGame(XmlTextWriter xtw, DatItem datItem)
-        {
-            // No game should start with a path separator
-            datItem.Machine.Name = datItem.Machine.Name.TrimStart(Path.DirectorySeparatorChar);
-
-            // Build the state
-            xtw.WriteStartElement("software");
-            xtw.WriteRequiredElementString("title", datItem.Machine.Name);
-            xtw.WriteRequiredElementString("genmsxid", datItem.Machine.GenMSXID);
-            xtw.WriteRequiredElementString("system", datItem.Machine.System);
-            xtw.WriteRequiredElementString("company", datItem.Machine.Manufacturer);
-            xtw.WriteRequiredElementString("year", datItem.Machine.Year);
-            xtw.WriteRequiredElementString("country", datItem.Machine.Country);
-
-            xtw.Flush();
-        }
-
+        /// Create a SoftwareDb from the current internal information
         /// <summary>
-        /// Write out Game start using the supplied StreamWriter
-        /// </summary>
-        /// <param name="xtw">XmlTextWriter to output to</param>
-        private void WriteEndGame(XmlTextWriter xtw)
+        /// <param name="ignoreblanks">True if blank roms should be skipped on output, false otherwise</param>
+        private Models.OpenMSX.SoftwareDb CreateSoftwareDb(bool ignoreblanks)
         {
-            // End software
-            xtw.WriteEndElement();
-
-            xtw.Flush();
-        }
-
-        /// <summary>
-        /// Write out DatItem using the supplied StreamWriter
-        /// </summary>
-        /// <param name="xtw">XmlTextWriter to output to</param>
-        /// <param name="datItem">DatItem object to be output</param>
-        private void WriteDatItem(XmlTextWriter xtw, DatItem datItem)
-        {
-            // Pre-process the item name
-            ProcessItemName(datItem, true);
-
-            // Build the state
-            switch (datItem.ItemType)
+            var softwaredb = new Models.OpenMSX.SoftwareDb
             {
-                case ItemType.Rom:
-                    var rom = datItem as Rom;
-                    xtw.WriteStartElement("dump");
+                Timestamp = Header.Date,
+                Software = CreateSoftwares(ignoreblanks)
+            };
+            return softwaredb;
+        }
 
-                    if (rom.Original != null)
+        /// <summary>
+        /// Create an array of Software from the current internal information
+        /// <summary>
+        /// <param name="ignoreblanks">True if blank roms should be skipped on output, false otherwise</param>
+        private Models.OpenMSX.Software[]? CreateSoftwares(bool ignoreblanks)
+        {
+            // If we don't have items, we can't do anything
+            if (this.Items == null || !this.Items.Any())
+                return null;
+
+            // Create a list of hold the games
+            var softwares = new List<Models.OpenMSX.Software>();
+
+            // Loop through the sorted items and create games for them
+            foreach (string key in Items.SortedKeys)
+            {
+                var items = Items.FilteredItems(key);
+                if (items == null || !items.Any())
+                    continue;
+
+                // Get the first item for game information
+                var machine = items[0].Machine;
+                var software = new Models.OpenMSX.Software
+                {
+                    Title = machine.Name,
+                    GenMSXID = machine.GenMSXID,
+                    System = machine.System,
+                    Company = machine.Manufacturer,
+                    Year = machine.Year,
+                    Country = machine.Country,
+                };
+
+                // Create holder for dumps
+                var dumps = new List<Models.OpenMSX.Dump>();
+
+                // Loop through and convert the items to respective lists
+                for (int index = 0; index < items.Count; index++)
+                {
+                    // Get the item
+                    var item = items[index];
+
+                    // Check for a "null" item
+                    item = ProcessNullifiedItem(item);
+
+                    // Skip if we're ignoring the item
+                    if (ShouldIgnore(item, ignoreblanks))
+                        continue;
+
+                    switch (item)
                     {
-                        xtw.WriteStartElement("original");
-                        xtw.WriteAttributeString("value", rom.Original.Value == true ? "true" : "false");
-                        xtw.WriteString(rom.Original.Content);
-                        xtw.WriteEndElement();
-                    }
-
-                    switch (rom.OpenMSXSubType)
-                    {
-                        // Default to Rom for converting from other formats
-                        case OpenMSXSubType.Rom:
-                        case OpenMSXSubType.NULL:
-                            xtw.WriteStartElement(rom.OpenMSXSubType.FromOpenMSXSubType());
-                            xtw.WriteRequiredElementString("hash", rom.SHA1?.ToLowerInvariant());
-                            xtw.WriteOptionalElementString("start", rom.Offset);
-                            xtw.WriteOptionalElementString("type", rom.OpenMSXType);
-                            xtw.WriteOptionalElementString("remark", rom.Remark);
-                            xtw.WriteEndElement();
-                            break;
-
-                        case OpenMSXSubType.MegaRom:
-                            xtw.WriteStartElement(rom.OpenMSXSubType.FromOpenMSXSubType());
-                            xtw.WriteRequiredElementString("hash", rom.SHA1?.ToLowerInvariant());
-                            xtw.WriteOptionalElementString("start", rom.Offset);
-                            xtw.WriteOptionalElementString("type", rom.OpenMSXType);
-                            xtw.WriteOptionalElementString("remark", rom.Remark);
-                            xtw.WriteEndElement();
-                            break;
-
-                        case OpenMSXSubType.SCCPlusCart:
-                            xtw.WriteStartElement(rom.OpenMSXSubType.FromOpenMSXSubType());
-                            xtw.WriteOptionalElementString("boot", rom.Boot);
-                            xtw.WriteRequiredElementString("hash", rom.SHA1?.ToLowerInvariant());
-                            xtw.WriteOptionalElementString("remark", rom.Remark);
-                            xtw.WriteEndElement();
+                        case Rom rom:
+                            dumps.Add(CreateDump(rom));
                             break;
                     }
+                }
 
-                    // End dump
-                    xtw.WriteEndElement();
-                    break;
+                software.Dump = dumps.ToArray();
+                softwares.Add(software);
             }
 
-            xtw.Flush();
+            return softwares.ToArray();
         }
 
         /// <summary>
-        /// Write out DAT footer using the supplied StreamWriter
-        /// </summary>
-        /// <param name="xtw">XmlTextWriter to output to</param>
-        private void WriteFooter(XmlTextWriter xtw)
+        /// Create a Dump from the current Rom DatItem
+        /// <summary>
+        private static Models.OpenMSX.Dump CreateDump(Rom item)
         {
-            // End software
-            xtw.WriteEndElement();
 
-            // End softwaredb
-            xtw.WriteEndElement();
+            Models.OpenMSX.Original original = null;
+            if (item.OriginalSpecified)
+            {
+                original = new Models.OpenMSX.Original { Content = item.Original.Content };
+                if (item.Original.Value != null)
+                    original.Value = item.Original.Value.ToString();
+            }
 
-            xtw.Flush();
+            Models.OpenMSX.RomBase rom = item.OpenMSXSubType switch
+            {
+                OpenMSXSubType.MegaRom => new Models.OpenMSX.MegaRom(),
+                OpenMSXSubType.SCCPlusCart => new Models.OpenMSX.SCCPlusCart(),
+                _ => new Models.OpenMSX.Rom(),
+            };
+
+            rom.Start = item.Offset;
+            rom.Type = item.OpenMSXType;
+            rom.Hash = item.SHA1;
+            rom.Remark = item.Remark;
+
+            var dump = new Models.OpenMSX.Dump
+            {
+                Original = original,
+                Rom = rom,
+            };
+
+            return dump;
         }
+
+        #endregion
     }
 }
diff --git a/SabreTools.DatFiles/Formats/OpenMSX.cs b/SabreTools.DatFiles/Formats/OpenMSX.cs
index 96983125..07c87a33 100644
--- a/SabreTools.DatFiles/Formats/OpenMSX.cs
+++ b/SabreTools.DatFiles/Formats/OpenMSX.cs
@@ -19,6 +19,23 @@
 <!ELEMENT dump (#PCDATA)>
 ";
 
+        private const string OpenMSXCredits = @"<!-- Credits -->
+<![CDATA[
+The softwaredb.xml file contains information about rom mapper types
+
+- Copyright 2003 Nicolas Beyaert (Initial Database)
+- Copyright 2004-2013 BlueMSX Team
+- Copyright 2005-2023 openMSX Team
+- Generation MSXIDs by www.generation-msx.nl
+
+- Thanks go out to:
+- - Generation MSX/Sylvester for the incredible source of information
+  - p_gimeno and diedel for their help adding and valdiating ROM additions
+  - GDX for additional ROM info and validations and corrections
+
+
+]]>";
+
         /// <summary>
         /// Constructor designed for casting a base DatFile
         /// </summary>
diff --git a/SabreTools.Models/OpenMSX/Original.cs b/SabreTools.Models/OpenMSX/Original.cs
index 35933355..7659b1d4 100644
--- a/SabreTools.Models/OpenMSX/Original.cs
+++ b/SabreTools.Models/OpenMSX/Original.cs
@@ -6,8 +6,9 @@ namespace SabreTools.Models.OpenMSX
     [XmlRoot("original")]
     public class Original
     {
+        /// <remarks>Boolean?</remarks>
         [XmlAttribute("value")]
-        public bool Value { get; set; }
+        public string? Value { get; set; }
 
         [XmlText]
         public string? Content { get; set; }
diff --git a/SabreTools.Test/Serialization/SerializationTests.cs b/SabreTools.Test/Serialization/SerializationTests.cs
index e31e410d..1a36f2c0 100644
--- a/SabreTools.Test/Serialization/SerializationTests.cs
+++ b/SabreTools.Test/Serialization/SerializationTests.cs
@@ -30,7 +30,7 @@ namespace SabreTools.Test.Parser
         {
             var original = new Models.OpenMSX.Original
             {
-                Value = false,
+                Value = "false",
                 Content = "Original Name",
             };