diff --git a/source/Cosmos.Core/CPU.cs b/source/Cosmos.Core/CPU.cs
index 14af04678..b8b3389a2 100644
--- a/source/Cosmos.Core/CPU.cs
+++ b/source/Cosmos.Core/CPU.cs
@@ -2,20 +2,25 @@
 using System.Collections.Generic;
 using System.Linq;
 using System.Text;
-
+using Cosmos.IL2CPU.Plugs;
 namespace Cosmos.Core {
     // Non hardware class, only used by core and hardware drivers for ports etc.
     public class CPU {
         // Amount of RAM in MB's.
         // needs to be static, as Heap needs it before we can instantiate objects
+        [PlugMethod(PlugRequired = true)]
         public static uint GetAmountOfRAM() { return 0; } // Plugged
         // needs to be static, as Heap needs it before we can instantiate objects
+        [PlugMethod(PlugRequired = true)]
         public static uint GetEndOfKernel() { return 0; } // Plugged
+        [PlugMethod(PlugRequired = true)]
         public void UpdateIDT(bool aEnableInterruptsImmediately) { } // Plugged
+        [PlugMethod(PlugRequired = true)]
         public void InitFloat() { } // Plugged
+        [PlugMethod(PlugRequired = true)]
         public static void ZeroFill(uint aStartAddress, uint aLength) { } // Plugged
+        [PlugMethod(PlugRequired = true)]
         public void Halt() { } // Plugged
-
         public void Reboot() {
             // Disable all interrupts
             DisableInterrupts();
diff --git a/source/Cosmos.Core/IOPort.cs b/source/Cosmos.Core/IOPort.cs
index fcd67fea9..d20672026 100644
--- a/source/Cosmos.Core/IOPort.cs
+++ b/source/Cosmos.Core/IOPort.cs
@@ -1,5 +1,5 @@
 using System;
-
+using Cosmos.IL2CPU.Plugs;
 namespace Cosmos.Core
 {
     public abstract class IOPortBase
@@ -29,12 +29,17 @@ namespace Cosmos.Core
         }
 
         //TODO: Reads and writes can use this to get port instead of argument
+        [PlugMethod(PlugRequired = true)]
         static protected void Write8(UInt16 aPort, byte aData) { } // Plugged
+        [PlugMethod(PlugRequired = true)]
         static protected void Write16(UInt16 aPort, UInt16 aData) { } // Plugged
+        [PlugMethod(PlugRequired = true)]
         static protected void Write32(UInt16 aPort, UInt32 aData) { } // Plugged
-
+        [PlugMethod(PlugRequired = true)]
         static protected byte Read8(UInt16 aPort) { return 0; } // Plugged
+        [PlugMethod(PlugRequired = true)]
         static protected UInt16 Read16(UInt16 aPort) { return 0; } // Plugged
+        [PlugMethod(PlugRequired = true)]
         static protected UInt32 Read32(UInt16 aPort) { return 0; } // Plugged
 
         //TODO: Plug these Reads with asm to read directly to RAM
diff --git a/source/Cosmos.IL2CPU.Plugs/PlugMethodAttribute.cs b/source/Cosmos.IL2CPU.Plugs/PlugMethodAttribute.cs
index 4d68dcddf..a617e2484 100644
--- a/source/Cosmos.IL2CPU.Plugs/PlugMethodAttribute.cs
+++ b/source/Cosmos.IL2CPU.Plugs/PlugMethodAttribute.cs
@@ -9,7 +9,7 @@ namespace Cosmos.IL2CPU.Plugs
     public Type Assembler = null;
     public bool IsMonoOnly = false;
     public bool IsMicrosoftdotNETOnly = false;
-    
+    public bool PlugRequired = false;
     public bool IsWildcard = false;
     public bool WildcardMatchParameters = false;
   }
diff --git a/source/Cosmos.IL2CPU/Heap.cs b/source/Cosmos.IL2CPU/Heap.cs
index 522cc4d72..e9e5bc39a 100644
--- a/source/Cosmos.IL2CPU/Heap.cs
+++ b/source/Cosmos.IL2CPU/Heap.cs
@@ -2,29 +2,29 @@
 using System.Collections.Generic;
 using System.Linq;
 using System.Text;
-
+using Cosmos.IL2CPU.Plugs;
 namespace Cosmos.IL2CPU {
 	partial class RuntimeEngine {
 		public static uint HeapHandle = 0;
 		public const uint InitialHeapSize = 4096;
 		public const uint MaximumHeapSize = 10 * 1024 * InitialHeapSize; // 10 megabytes
-		public static void Heap_Initialize() {
+        public static void Heap_Initialize() {
 			//HeapHandle = PInvokes.Kernel32_HeapCreate(0, InitialHeapSize, MaximumHeapSize);
 		}
-
-		public static uint Heap_AllocNewObject(uint aSize) {
+        [PlugMethod(PlugRequired = true)]
+        public static uint Heap_AllocNewObject(uint aSize) {
 //			if (aSize == 0) {
 //				aSize = 1;
 //			}
 			//return PInvokes.Kernel32_HeapAlloc(HeapHandle, 0x00000008, aSize);
 			return 0;
 		}
-
-		public static void Heap_Free(uint aObject) {
+        [PlugMethod(PlugRequired = true)]
+        public static void Heap_Free(uint aObject) {
 			//
 		}
-
-		public static void Heap_Shutdown() {
+        [PlugMethod(PlugRequired = true)]
+        public static void Heap_Shutdown() {
 			//PInvokes.Kernel32_HeapDestroy(HeapHandle);
 			//HeapHandle = 0;
 		}
diff --git a/source/Cosmos.IL2CPU/ILScanner.cs b/source/Cosmos.IL2CPU/ILScanner.cs
index 4c9c5066f..f203ffa7b 100644
--- a/source/Cosmos.IL2CPU/ILScanner.cs
+++ b/source/Cosmos.IL2CPU/ILScanner.cs
@@ -918,6 +918,10 @@ namespace Cosmos.IL2CPU
                             {
                                 continue;
                             }
+                            else if(xAttrib.PlugRequired)
+                            {
+                                throw new Exception(string.Format("Method {0} requires a plug, but none is implemented",xMethod.Name));
+                            }
                             xPlugAssembler = xAttrib.Assembler;
                         }