diff --git a/EightBit/InputOutput.cs b/EightBit/InputOutput.cs
index 2d774be..aafbc7f 100644
--- a/EightBit/InputOutput.cs
+++ b/EightBit/InputOutput.cs
@@ -17,31 +17,32 @@ namespace EightBit
 
         public event EventHandler<PortEventArgs>? WrittenPort;
 
-        public byte Read(ushort port) => this.ReadInputPort(port);
 
-        public byte Read(Register16 port) => this.Read(port.Word);
+        public byte Read(Register16 port) => this.ReadInputPort(port);
 
-        public void Write(ushort port, byte value) => this.WriteOutputPort(port, value);
-
-        public void Write(Register16 port, byte value) => this.Write(port.Word, value);
-
-        public byte ReadInputPort(ushort port)
+        public byte ReadInputPort(Register16 port)
         {
             ReadingPort?.Invoke(this, new PortEventArgs(port));
-            var value = this._input[port];
+            var value = this._input[port.Word];
             ReadPort?.Invoke(this, new PortEventArgs(port));
             return value;
         }
 
         public void WriteInputPort(ushort port, byte value) => this._input[port] = value;
 
-        public byte ReadOutputPort(ushort port) => this._output[port];
+        public void WriteInputPort(Register16 port, byte value) => this.WriteInputPort(port.Word, value);
 
-        public void WriteOutputPort(ushort port, byte value)
+        public void Write(Register16 port, byte value) => this.WriteOutputPort(port, value);
+
+        public void WriteOutputPort(Register16 port, byte value)
         {
             WritingPort?.Invoke(this, new PortEventArgs(port));
-            this._output[port] = value;
+            this._output[port.Word] = value;
             WrittenPort?.Invoke(this, new PortEventArgs(port));
         }
+
+        public byte ReadOutputPort(ushort port) => this._output[port];
+
+        public byte ReadOutputPort(Register16 port) => this.ReadOutputPort(port.Word);
     }
 }
diff --git a/EightBit/PortEventArgs.cs b/EightBit/PortEventArgs.cs
index a98907b..bbd7650 100644
--- a/EightBit/PortEventArgs.cs
+++ b/EightBit/PortEventArgs.cs
@@ -4,8 +4,8 @@
 
 namespace EightBit
 {
-    public sealed class PortEventArgs(ushort value) : EventArgs
+    public sealed class PortEventArgs(Register16 value) : EventArgs
     {
-        public ushort Port { get; } = value;
+        public Register16 Port { get; } = value;
     }
 }
diff --git a/Z80/Z80.HarteTest/Checker.cs b/Z80/Z80.HarteTest/Checker.cs
index 92da725..54e9339 100644
--- a/Z80/Z80.HarteTest/Checker.cs
+++ b/Z80/Z80.HarteTest/Checker.cs
@@ -407,14 +407,13 @@
 
             foreach (var port in ports)
             {
-                var value = port.Value;
                 if (port.Type == "r")
                 {
-                    cpu.Ports.WriteInputPort(port.Address, value);
+                    cpu.Ports.WriteInputPort(port.Address, port.Value);
                 }
                 else if (port.Type == "w")
                 {
-                    cpu.Ports.WriteOutputPort(port.Address, value);
+                    cpu.Ports.WriteOutputPort(new Register16(port.Address), port.Value);
                 }
                 else
                 {