diff --git a/lib/register/passes/call_implementation.rb b/lib/register/passes/call_implementation.rb
new file mode 100644
index 00000000..81b37246
--- /dev/null
+++ b/lib/register/passes/call_implementation.rb
@@ -0,0 +1,27 @@
+module Register
+
+  # Defines the method call, ie 
+  # - move the new_message to message
+  # - unroll self and
+  # - register call
+
+  # all in all, quite the reverse of a return
+
+  class CallImplementation
+    def run block
+      block.codes.dup.each do |code|
+        next unless code.is_a? Virtual::MethodCall
+        new_codes = []
+        slot = Virtual::Slot
+        # move the current new_message to message
+        new_codes << RegisterTransfer.new( slot::NEW_MESSAGE_REGISTER , slot::MESSAGE_REGISTER )
+        # "roll out" self into its register
+        new_codes << GetSlot.new( slot::SELF_REGISTER ,slot::MESSAGE_REGISTER , slot::MESSAGE_SELF )
+        # do the register call
+        new_codes << FunctionCall.new( code.method )
+        block.replace(code , new_codes )
+      end
+    end
+  end
+  Virtual::BootSpace.space.add_pass "Register::CallImplementation"
+end
diff --git a/lib/register/register_machine.rb b/lib/register/register_machine.rb
index 89d25a42..d1f5e1d8 100644
--- a/lib/register/register_machine.rb
+++ b/lib/register/register_machine.rb
@@ -3,3 +3,4 @@ require_relative "register_reference"
 require_relative "assembler"
 require_relative "passes/set_implementation"
 require_relative "passes/return_implementation"
+require_relative "passes/call_implementation"