diff --git a/M6502/M6502.Symbols/Parser.cs b/M6502/M6502.Symbols/Parser.cs
index f7ef130..1c86d2d 100644
--- a/M6502/M6502.Symbols/Parser.cs
+++ b/M6502/M6502.Symbols/Parser.cs
@@ -296,13 +296,18 @@
 
                 #region Parser driver
 
-                public void Parse(string path)
+                public void Parse(string? path)
                 {
                     if (this.Parsed)
                     {
                         throw new InvalidOperationException("A file has already been parsed.");
                     }
 
+                    if (string.IsNullOrEmpty(path))
+                    {
+                        return;
+                    }
+
                     using var reader = new StreamReader(path);
                     while (!reader.EndOfStream)
                     {
diff --git a/M6502/M6502.Test/Board.cs b/M6502/M6502.Test/Board.cs
index 1687fdb..19f11de 100644
--- a/M6502/M6502.Test/Board.cs
+++ b/M6502/M6502.Test/Board.cs
@@ -38,17 +38,6 @@ namespace M6502.Test
             this.symbols.Parse(string.IsNullOrEmpty(this.configuration.Symbols) ? string.Empty : this.configuration.RomDirectory + "/"  + this.configuration.Symbols);
 
             this.profiler = new Profiler(this.CPU, this.disassembler, this.symbols, this.configuration.Profile, this.configuration.Profile);
-            if (this.configuration.Profile)
-            {
-                this.profiler.StartingOutput += this.Profiler_StartingOutput;
-                this.profiler.FinishedOutput += this.Profiler_FinishedOutput;
-                this.profiler.StartingLineOutput += this.Profiler_StartingLineOutput;
-                this.profiler.FinishedLineOutput += this.Profiler_FinishedLineOutput;
-                this.profiler.StartingScopeOutput += this.Profiler_StartingScopeOutput;
-                this.profiler.FinishedScopeOutput += this.Profiler_FinishedScopeOutput;
-                this.profiler.EmitLine += this.Profiler_EmitLine;
-                this.profiler.EmitScope += this.Profiler_EmitScope;
-            }
         }
 
         public M6502 CPU { get; }
@@ -100,6 +89,18 @@ namespace M6502.Test
                 this.CPU.Bus.ReadByte += this.Bus_ReadByte;
             }
 
+            if (this.configuration.Profile)
+            {
+                this.profiler.StartingOutput += this.Profiler_StartingOutput;
+                this.profiler.FinishedOutput += this.Profiler_FinishedOutput;
+                this.profiler.StartingLineOutput += this.Profiler_StartingLineOutput;
+                this.profiler.FinishedLineOutput += this.Profiler_FinishedLineOutput;
+                this.profiler.StartingScopeOutput += this.Profiler_StartingScopeOutput;
+                this.profiler.FinishedScopeOutput += this.Profiler_FinishedScopeOutput;
+                this.profiler.EmitLine += this.Profiler_EmitLine;
+                this.profiler.EmitScope += this.Profiler_EmitScope;
+            }
+
             this.Poke(0x00, 0x4c);
             this.CPU.PokeWord(0x01, this.configuration.StartAddress);
         }
diff --git a/M6502/M6502.Test/Configuration.cs b/M6502/M6502.Test/Configuration.cs
index f135c77..b2a5043 100644
--- a/M6502/M6502.Test/Configuration.cs
+++ b/M6502/M6502.Test/Configuration.cs
@@ -8,26 +8,33 @@ namespace M6502.Test
 
     internal class Configuration
     {
-        public Configuration()
-        {
-        }
-
         public bool DebugMode { get; set; } = false;
 
-        public bool BreakOnRead { get; } = true;
+        public bool Profile { get; set; } = true;
 
-        public Register16 LoadAddress { get; } = new Register16(0x400);
+        public bool BreakOnKeyRead { get; } = true;
 
-        public Register16 StartAddress { get; } = new Register16(0x400);
 
+        // Sudoku
+        //public string Program { get; } = "sudoku.65b";
+        //public string Symbols { get; } = "sudoku.dbg";
+        //public Register16 InputAddress { get; } = new Register16(0xe000);
+        //public Register16 OutputAddress { get; } = new Register16(0xe001);
+        //public Register16 LoadAddress { get; } = new Register16(0xf000);
+        //public Register16 StartAddress { get; } = new Register16(0xf000);
+        //public bool AllowKeyRead { get; } = false;
+
+        // Klaus
+        public string Program { get; } = "6502_functional_test.bin";
+        public string Symbols { get; } = "";
         public Register16 InputAddress { get; } = new Register16(0xf004);
-
         public Register16 OutputAddress { get; } = new Register16(0xf001);
+        public Register16 LoadAddress { get; } = new Register16(0x400);
+        public Register16 StartAddress { get; } = new Register16(0x400);
+        public bool AllowKeyRead { get; } = true;
 
         public int PollingTickInterval { get; } = 10000000;
 
         public string RomDirectory { get; } = "roms";
-
-        public string Program { get; } = "6502_functional_test.bin";
     }
 }
\ No newline at end of file