diff --git a/lib/risc/builtin.rb b/lib/mom/builtin.rb
similarity index 98%
rename from lib/risc/builtin.rb
rename to lib/mom/builtin.rb
index be76923d..2148cb2a 100644
--- a/lib/risc/builtin.rb
+++ b/lib/mom/builtin.rb
@@ -1,4 +1,4 @@
-  module Risc
+module Mom
   module Builtin
     module CompileHelper
 
@@ -16,7 +16,7 @@ require_relative "builtin/integer"
 require_relative "builtin/object"
 require_relative "builtin/word"
 
-module Risc
+module Mom
   module Builtin
     # classes have booted, now create a minimal set of functions
     # minimal means only that which can not be coded in ruby
diff --git a/lib/risc/builtin/README.md b/lib/mom/builtin/README.md
similarity index 100%
rename from lib/risc/builtin/README.md
rename to lib/mom/builtin/README.md
diff --git a/lib/risc/builtin/integer.rb b/lib/mom/builtin/integer.rb
similarity index 99%
rename from lib/risc/builtin/integer.rb
rename to lib/mom/builtin/integer.rb
index 46419002..23154e58 100644
--- a/lib/risc/builtin/integer.rb
+++ b/lib/mom/builtin/integer.rb
@@ -1,4 +1,4 @@
-module Risc
+module Mom
   module Builtin
     # integer related kernel functions
     # all these functions (return the function they implement) assume interger input
diff --git a/lib/risc/builtin/object.rb b/lib/mom/builtin/object.rb
similarity index 95%
rename from lib/risc/builtin/object.rb
rename to lib/mom/builtin/object.rb
index b8a91b11..d0c99224 100644
--- a/lib/risc/builtin/object.rb
+++ b/lib/mom/builtin/object.rb
@@ -1,4 +1,4 @@
-module Risc
+module Mom
   module Builtin
     class Object
       module ClassMethods
@@ -133,7 +133,7 @@ module Risc
     # there is a Syscall instruction, but the message has to be saved and restored
     def self.emit_syscall( builder , name )
       save_message( builder )
-      builder.add_code Syscall.new("emit_syscall(#{name})", name )
+      builder.add_code Risc::Syscall.new("emit_syscall(#{name})", name )
       restore_message(builder)
       return unless (@clazz and @method)
       builder.add_code Risc.label( "#{@clazz.name}.#{@message.name}" , "return_syscall" )
@@ -147,7 +147,7 @@ module Risc
       builder.build do
         message << message[:return_value]
         message.reduce_int
-        add_code Syscall.new("emit_syscall(exit)", :exit )
+        add_code Risc::Syscall.new("emit_syscall(exit)", :exit )
       end
     end
 
@@ -156,7 +156,7 @@ module Risc
     # This relies on linux to save and restore all registers
     #
     def self.save_message(builder)
-      r8 = RegisterValue.new( :r8 , :Message).set_builder(builder)
+      r8 = Risc::RegisterValue.new( :r8 , :Message).set_builder(builder)
       builder.build {r8 << message}
     end
 
@@ -166,7 +166,7 @@ module Risc
     # so that the return value already has an integer instance
     # This instance is filled with os return value
     def self.restore_message(builder)
-      r8 = RegisterValue.new( :r8 , :Message)
+      r8 = Risc::RegisterValue.new( :r8 , :Message)
       builder.build do
         integer_reg! << message
         message << r8
diff --git a/lib/risc/builtin/space.rb b/lib/mom/builtin/space.rb
similarity index 96%
rename from lib/risc/builtin/space.rb
rename to lib/mom/builtin/space.rb
index ec638d0f..61999513 100644
--- a/lib/risc/builtin/space.rb
+++ b/lib/mom/builtin/space.rb
@@ -1,4 +1,4 @@
-module Risc
+module Mom
   module Builtin
     class Space
       module ClassMethods
diff --git a/lib/risc/builtin/word.rb b/lib/mom/builtin/word.rb
similarity index 97%
rename from lib/risc/builtin/word.rb
rename to lib/mom/builtin/word.rb
index 54e4f9b0..67814f57 100644
--- a/lib/risc/builtin/word.rb
+++ b/lib/mom/builtin/word.rb
@@ -1,4 +1,4 @@
-module Risc
+module Mom
   module Builtin
     module Word
       module ClassMethods
@@ -23,7 +23,7 @@ module Risc
               word! << message[:receiver]
               integer! << word[Parfait::Word.get_length_index]
             end
-            Risc::Builtin.emit_syscall( builder , :putstring )
+            Mom::Builtin.emit_syscall( builder , :putstring )
             compiler
           end
         end
diff --git a/lib/mom/mom.rb b/lib/mom/mom.rb
index 132c2661..22e0dbfb 100644
--- a/lib/mom/mom.rb
+++ b/lib/mom/mom.rb
@@ -12,6 +12,10 @@
 # Machine capabilities (instructions) for basic operations. Use of macros for higher level.
 
 module Mom
+  # boot bubiltin function (subject to change)
+  def self.boot!
+    Builtin.boot_functions
+  end
 end
 
 require_relative "instruction.rb"
@@ -19,3 +23,4 @@ require_relative "mom_collection"
 require_relative "callable_compiler"
 require_relative "method_compiler"
 require_relative "block_compiler"
+require_relative "builtin"
diff --git a/lib/risc.rb b/lib/risc.rb
index 40fa9a4e..65ab5c54 100644
--- a/lib/risc.rb
+++ b/lib/risc.rb
@@ -12,15 +12,11 @@ class Class
   end
 end
 
-# The Risc Machine, is an abstract machine with registers. Think of it as an arm machine with
-# normal instruction names. It is not however an abstraction of existing hardware, but only
-# of that subset that we need.
 # See risc/Readme
 module Risc
   # module method to reset, and init
   def self.boot!
     Position.clear_positions
-    Builtin.boot_functions
   end
 end
 
@@ -47,5 +43,4 @@ end
 require_relative "risc/instruction"
 require_relative "risc/register_value"
 require_relative "risc/text_writer"
-require_relative "risc/builtin"
 require_relative "risc/builder"
diff --git a/lib/rubyx.rb b/lib/rubyx.rb
index 05e9450e..1e849175 100644
--- a/lib/rubyx.rb
+++ b/lib/rubyx.rb
@@ -3,8 +3,8 @@ require "rx-file"
 require "util/logging"
 require "util/list"
 require_relative "elf/object_writer"
-require_relative "mom/mom"
 require_relative "risc"
+require_relative "mom/mom"
 require_relative "arm/arm_machine"
 require_relative "arm/arm_platform"
 require_relative "vool/statement"
diff --git a/lib/rubyx/rubyx_compiler.rb b/lib/rubyx/rubyx_compiler.rb
index b0c84371..d6249c0c 100644
--- a/lib/rubyx/rubyx_compiler.rb
+++ b/lib/rubyx/rubyx_compiler.rb
@@ -21,6 +21,7 @@ module RubyX
     # initialize boots Parfait and Risc (ie load Builin)
     def initialize(options)
       Parfait.boot!(options[:parfait] || {})
+      Mom.boot!
       Risc.boot!
     end
 
diff --git a/test/mom/builtin/README.md b/test/mom/builtin/README.md
new file mode 100644
index 00000000..b632d710
--- /dev/null
+++ b/test/mom/builtin/README.md
@@ -0,0 +1,8 @@
+# Builtin Testing
+
+Mostly testing that
+- functions exist
+- they compile
+- basic length tests (no "contents")
+
+Functionality is tested by interpreter over in interpreter dir
diff --git a/test/risc/builtin/helper.rb b/test/mom/builtin/helper.rb
similarity index 76%
rename from test/risc/builtin/helper.rb
rename to test/mom/builtin/helper.rb
index 55dea0ce..2be0a87b 100644
--- a/test/risc/builtin/helper.rb
+++ b/test/mom/builtin/helper.rb
@@ -1,12 +1,7 @@
 require_relative "../helper"
 
-module Risc
+module Mom
   module Builtin
-    class BuiltinTest < MiniTest::Test
-      include Ticker
-      def setup
-      end
-    end
     class BootTest < MiniTest::Test
       def setup
         Parfait.boot!(Parfait.default_test_options)
diff --git a/test/risc/builtin/test_integer.rb b/test/mom/builtin/test_integer.rb
similarity index 99%
rename from test/risc/builtin/test_integer.rb
rename to test/mom/builtin/test_integer.rb
index 807854d0..21a7e90e 100644
--- a/test/risc/builtin/test_integer.rb
+++ b/test/mom/builtin/test_integer.rb
@@ -1,6 +1,6 @@
 require_relative "helper"
 
-module Risc
+module Mom
   module Builtin
     class TestIntDiv4 < BootTest
       def setup
diff --git a/test/risc/builtin/test_object.rb b/test/mom/builtin/test_object.rb
similarity index 99%
rename from test/risc/builtin/test_object.rb
rename to test/mom/builtin/test_object.rb
index 277942b6..4472a420 100644
--- a/test/risc/builtin/test_object.rb
+++ b/test/mom/builtin/test_object.rb
@@ -1,6 +1,6 @@
 require_relative "helper"
 
-module Risc
+module Mom
   module Builtin
     class TestObjectFunctionGet < BootTest
       def setup
diff --git a/test/risc/builtin/test_word.rb b/test/mom/builtin/test_word.rb
similarity index 99%
rename from test/risc/builtin/test_word.rb
rename to test/mom/builtin/test_word.rb
index e257f578..e1801db7 100644
--- a/test/risc/builtin/test_word.rb
+++ b/test/mom/builtin/test_word.rb
@@ -1,6 +1,6 @@
 require_relative "helper"
 
-module Risc
+module Mom
   module Builtin
     class TestWordPut < BootTest
       def setup
diff --git a/test/risc/test_builtin.rb b/test/mom/test_builtin.rb
similarity index 97%
rename from test/risc/test_builtin.rb
rename to test/mom/test_builtin.rb
index 2edf442e..3ccdde52 100644
--- a/test/risc/test_builtin.rb
+++ b/test/mom/test_builtin.rb
@@ -1,6 +1,6 @@
 require_relative "helper"
 
-module Risc
+module Mom
   class TestBuiltinFunction < MiniTest::Test
 
     def setup
diff --git a/test/risc/builtin/README.md b/test/risc/interpreter/builtin/README.md
similarity index 100%
rename from test/risc/builtin/README.md
rename to test/risc/interpreter/builtin/README.md
diff --git a/test/risc/builtin/test_int_cmp.rb b/test/risc/interpreter/builtin/test_int_cmp.rb
similarity index 96%
rename from test/risc/builtin/test_int_cmp.rb
rename to test/risc/interpreter/builtin/test_int_cmp.rb
index 902637c0..af8b66da 100644
--- a/test/risc/builtin/test_int_cmp.rb
+++ b/test/risc/interpreter/builtin/test_int_cmp.rb
@@ -1,9 +1,12 @@
 require_relative "helper"
 
 # TODO move these to interpreter dir
-module Risc
+module Mom
   module Builtin
     class IntCmp < BuiltinTest
+      include Ticker
+      def setup
+      end
 
       def test_smaller_true
         run_main_return "4 < 5"
diff --git a/test/risc/builtin/test_int_math.rb b/test/risc/interpreter/builtin/test_int_math.rb
similarity index 94%
rename from test/risc/builtin/test_int_math.rb
rename to test/risc/interpreter/builtin/test_int_math.rb
index fe9fd893..c22cc652 100644
--- a/test/risc/builtin/test_int_math.rb
+++ b/test/risc/interpreter/builtin/test_int_math.rb
@@ -1,8 +1,11 @@
 require_relative "helper"
 
-module Risc
+module Mom
   module Builtin
     class IntMath < BuiltinTest
+      include Ticker
+      def setup
+      end
 
       def test_add
         run_main_return "5 + 5"
diff --git a/test/vool/send/helper.rb b/test/vool/send/helper.rb
index 04651c92..1f860562 100644
--- a/test/vool/send/helper.rb
+++ b/test/vool/send/helper.rb
@@ -8,7 +8,7 @@ module Vool
 
     def setup
       Parfait.boot!(Parfait.default_test_options)
-      Risc::Builtin.boot_functions
+      Mom.boot!
       @compiler = compile_first_method( send_method )
       @ins = @compiler.mom_instructions.next
     end