diff --git a/BizHawk.Emulation.DiscSystem/Blobs/Blob_ZeroPadAdapter.cs b/BizHawk.Emulation.DiscSystem/Blobs/Blob_ZeroPadAdapter.cs
index 29ed678875..f9dcaa8f8b 100644
--- a/BizHawk.Emulation.DiscSystem/Blobs/Blob_ZeroPadAdapter.cs
+++ b/BizHawk.Emulation.DiscSystem/Blobs/Blob_ZeroPadAdapter.cs
@@ -7,6 +7,21 @@ namespace BizHawk.Emulation.DiscSystem
 {
 	public partial class Disc : IDisposable
 	{
+		/// <summary>
+		/// A blob that always reads 0
+		/// </summary>
+		internal sealed class Blob_Zeros : IBlob
+		{
+			public int Read(long byte_pos, byte[] buffer, int offset, int count)
+			{
+				Array.Clear(buffer, offset, count);
+				return count;
+			}
+
+			public void Dispose()
+			{
+			}
+		}
 
 		internal sealed class Blob_ZeroPadAdapter : IBlob
 		{
diff --git a/BizHawk.Emulation.DiscSystem/CUE/CUE_Load.cs b/BizHawk.Emulation.DiscSystem/CUE/CUE_Load.cs
index fad529cdcf..1d2fa3234e 100644
--- a/BizHawk.Emulation.DiscSystem/CUE/CUE_Load.cs
+++ b/BizHawk.Emulation.DiscSystem/CUE/CUE_Load.cs
@@ -209,7 +209,7 @@ namespace BizHawk.Emulation.DiscSystem
 					{
 						//TODO - do a better job synthesizing Q
 						var se_pregap = new SectorEntry(null);
-						var ss_pregap = new SS_Pregap();
+						var ss_pregap = new SS_Gap();
 						
 						//pregaps set pause flag
 						//TODO - do a better job synthesizing P
@@ -343,7 +343,7 @@ namespace BizHawk.Emulation.DiscSystem
 					{
 						//TODO - do a better job synthesizing Q
 						var se_pregap = new SectorEntry(null);
-						var ss_pregap = new SS_Pregap();
+						var ss_pregap = new SS_Gap();
 
 						//postgaps set pause flag. is this good enough?
 						ss_pregap.Pause = true;
diff --git a/BizHawk.Emulation.DiscSystem/CUE/CUE_Synths.cs b/BizHawk.Emulation.DiscSystem/CUE/CUE_Synths.cs
index c23c071976..8d3477b08b 100644
--- a/BizHawk.Emulation.DiscSystem/CUE/CUE_Synths.cs
+++ b/BizHawk.Emulation.DiscSystem/CUE/CUE_Synths.cs
@@ -19,7 +19,7 @@ namespace BizHawk.Emulation.DiscSystem
 			{
 				if ((job.Parts & ESectorSynthPart.SubchannelP) != 0)
 				{
-					SynthUtils.P(job.DestBuffer2448, job.DestOffset + 2352, Pause);
+					SynthUtils.SubP(job.DestBuffer2448, job.DestOffset + 2352, Pause);
 				}
 
 				if ((job.Parts & ESectorSynthPart.SubchannelQ) != 0)
@@ -33,14 +33,14 @@ namespace BizHawk.Emulation.DiscSystem
 
 		static class SynthUtils
 		{
-			public static void P(byte[] buffer, int offset, bool pause)
+			public static void SubP(byte[] buffer, int offset, bool pause)
 			{
 				byte val = (byte)(pause?0xFF:0x00);
 				for (int i = 0; i < 12; i++)
 					buffer[offset + i] = val;
 			}
 
-			public static void Header(byte[] buffer, int offset, int LBA, byte mode)
+			public static void SectorHeader(byte[] buffer, int offset, int LBA, byte mode)
 			{
 				buffer[offset + 0] = 0x00;
 				for (int i = 1; i < 11; i++) buffer[offset + i] = 0xFF;
@@ -51,17 +51,21 @@ namespace BizHawk.Emulation.DiscSystem
 				buffer[offset + 14] = ts.FRAC;
 				buffer[offset + 15] = mode;
 			}
-		}
 
-		/// <summary>
-		/// Represents a pregap sector
-		/// TODO - represent any zero sector
-		/// </summary>
-		class SS_Pregap : SS_Base
-		{
-			public override void Synth(SectorSynthJob job)
+			/// <summary>
+			/// Make sure everything else in the sector userdata is done before calling this
+			/// </summary>
+			public static void ECM_Mode1(byte[] buffer, int offset, int LBA)
 			{
+				//EDC
+				uint edc = ECM.EDC_Calc(buffer, offset, 2064);
+				ECM.PokeUint(buffer, 2064, edc);
+
+				//reserved, zero
+				for (int i = 0; i < 8; i++) buffer[offset + 2068 + i] = 0;
 				
+				//ECC
+				ECM.ECC_Populate(buffer, offset, buffer, offset, false);
 			}
 		}
 
@@ -77,12 +81,27 @@ namespace BizHawk.Emulation.DiscSystem
 					Blob.Read(BlobOffset, job.DestBuffer2448, job.DestOffset + 16, 2048);
 
 				if ((job.Parts & ESectorSynthPart.Header16) != 0)
-					SynthUtils.Header(job.DestBuffer2448, job.DestOffset + 0, job.LBA, 1);
+					SynthUtils.SectorHeader(job.DestBuffer2448, job.DestOffset + 0, job.LBA, 1);
+
+				if ((job.Parts & ESectorSynthPart.ECMAny) != 0)
+					SynthUtils.ECM_Mode1(job.DestBuffer2448, job.DestOffset + 0, job.LBA);
 
 				SynthSubcode(job);
 			}
 		}
 
+		/// <summary>
+		/// Represents a pregap or postgap sector.
+		/// The Pause flag isn't set in here because it might need special logic varying between sectors
+		/// Implemented as another sector type with a blob reading all zeros
+		/// </summary>
+		class SS_Gap : SS_Mode1_2048
+		{
+			public SS_Gap()
+			{
+				Blob = new Disc.Blob_Zeros();
+			}
+		}
 
 		/// <summary>
 		/// Represents a Mode1 or Mode2 2352-byte sector
diff --git a/BizHawk.Emulation.DiscSystem/ECM.cs b/BizHawk.Emulation.DiscSystem/ECM.cs
index 945186ae4c..744d447873 100644
--- a/BizHawk.Emulation.DiscSystem/ECM.cs
+++ b/BizHawk.Emulation.DiscSystem/ECM.cs
@@ -226,7 +226,8 @@ namespace BizHawk.Emulation.DiscSystem
 				(sector[sector_offset + 12 + 0] << 0)
 				| (sector[sector_offset + 12 + 1] << 8)
 				| (sector[sector_offset + 12 + 2] << 16)
-				| (sector[sector_offset + 12 + 3] << 24));
+			);
+				//| (sector[sector_offset + 12 + 3] << 24));
 		}
 
 		/// <summary>
@@ -237,7 +238,7 @@ namespace BizHawk.Emulation.DiscSystem
 			sector[sector_offset + 12 + 0] = (byte)((address >> 0) & 0xFF);
 			sector[sector_offset + 12 + 1] = (byte)((address >> 8) & 0xFF);
 			sector[sector_offset + 12 + 2] = (byte)((address >> 16) & 0xFF);
-			sector[sector_offset + 12 + 3] = (byte)((address >> 24) & 0xFF);
+			//sector[sector_offset + 12 + 3] = (byte)((address >> 24) & 0xFF);
 		}
 
 
diff --git a/BizHawk.Emulation.DiscSystem/Jobs/DiscMountJob.cs b/BizHawk.Emulation.DiscSystem/Jobs/DiscMountJob.cs
index 9018f268f4..adbaf394fc 100644
--- a/BizHawk.Emulation.DiscSystem/Jobs/DiscMountJob.cs
+++ b/BizHawk.Emulation.DiscSystem/Jobs/DiscMountJob.cs
@@ -9,6 +9,7 @@ namespace BizHawk.Emulation.DiscSystem
 	/// <summary>
 	/// General disc policies to be logically applied at mounting time. The choices are irreversible once a disc is loaded.
 	/// Maybe these are only for CUEs, but maybe not. Not sure yet.
+	/// Could put caching policies here too (cached ecm calculations, etc.)
 	/// </summary>
 	public class DiscMountPolicy
 	{
diff --git a/BizHawk.Emulation.DiscSystem/SectorInterfaces.cs b/BizHawk.Emulation.DiscSystem/SectorInterfaces.cs
index 876c4b030d..4d04aed806 100644
--- a/BizHawk.Emulation.DiscSystem/SectorInterfaces.cs
+++ b/BizHawk.Emulation.DiscSystem/SectorInterfaces.cs
@@ -47,10 +47,20 @@ namespace BizHawk.Emulation.DiscSystem
 		/// </summary>
 		EDC12 = 8,
 
+		/// <summary>
+		/// The entire possible 276+12=288 bytes of ECM data is required (ECC276|EDC12)
+		/// </summary>
+		ECM288Complete = (ECC276 | EDC12),
+
+		/// <summary>
+		/// An alias for ECM288Complete
+		/// </summary>
+		ECMAny = ECM288Complete,
+
 		/// <summary>
 		/// A mode2 userdata section is required: the main 2048 user bytes AND the ECC and EDC areas
 		/// </summary>
-		User2336 = (User2048|ECC276|EDC12),
+		User2336 = (User2048 | ECM288Complete),
 
 		/// <summary>
 		/// The complete sector userdata (2352 bytes) is required