diff --git a/lib/risc/interpreter.rb b/lib/risc/interpreter.rb
index 0bf91f2e..10b7aa16 100644
--- a/lib/risc/interpreter.rb
+++ b/lib/risc/interpreter.rb
@@ -267,7 +267,7 @@ module Risc
     end
 
     def handle_putstring
-      str = get_register( :"syscall_1" ) # should test length, ie r2
+      str = get_register( :r0 ) # should test length, ie r2
       case str
       when Symbol
         @stdout << str.to_s
diff --git a/lib/risc/platform.rb b/lib/risc/platform.rb
index 6469ea39..50e4f284 100644
--- a/lib/risc/platform.rb
+++ b/lib/risc/platform.rb
@@ -40,6 +40,8 @@ module Risc
         :r0
       when :syscall_2
         :r1
+      when :saved_message
+        :r15
       else
         nil
       end
diff --git a/test/risc/interpreter/assign/test_assign_local.rb b/test/risc/interpreter/assign/test_assign_local.rb
index 60fa8afe..8d325b09 100644
--- a/test/risc/interpreter/assign/test_assign_local.rb
+++ b/test/risc/interpreter/assign/test_assign_local.rb
@@ -24,7 +24,7 @@ module Risc
       assert  :main , call_ins.method.name
     end
     def test_load_15
-      assert_load 1 , Parfait::Integer , "id_integer_"
+      assert_load 1 , Parfait::Integer , :r1
       assert_equal 15 , @interpreter.get_register(@interpreter.instruction.register).value
     end
     def test_branch
@@ -37,7 +37,7 @@ module Risc
       assert_equal Parfait::ReturnAddress , link.class
     end
     def test_transfer
-      assert_transfer 12 , :message , :saved_message
+      assert_transfer 12 , :r0 , :r15
     end
     def test_sys
       assert_syscall 16 , :exit
diff --git a/test/risc/interpreter/calling/test_alloc.rb b/test/risc/interpreter/calling/test_alloc.rb
index d5885b47..5164ec34 100644
--- a/test/risc/interpreter/calling/test_alloc.rb
+++ b/test/risc/interpreter/calling/test_alloc.rb
@@ -28,17 +28,17 @@ module Risc
     end
 
     def test_load_factory
-      assert_load( 15 , Parfait::Factory , "id_factory_")
+      assert_load( 15 , Parfait::Factory , :r1)
       assert_equal :next_integer , @instruction.constant.attribute_name
     end
     def test_load_nil
-      assert_load( 16 , Parfait::NilClass , "id_nilclass_")
+      assert_load( 16 , Parfait::NilClass , :r2)
     end
     def test_slot_receiver #load next_object from factory
-      assert_slot_to_reg( 17 , "id_factory_" , 2 , "id_factory_.next_object")
+      assert_slot_to_reg( 17 , :r1 , 2 , :r3)
     end
     def test_nil_check
-      assert_operator 18 , :- ,  "id_nilclass_" , "id_factory_.next_object" , "op_-_"
+      assert_operator 18 , :- ,  :r2 , :r3 , :r4
       value = @interpreter.get_register(@instruction.result)
       assert_equal ::Integer , value.class
       assert 0 != value
@@ -47,10 +47,10 @@ module Risc
       assert_not_zero 19 , "cont_label"
     end
     def test_load_next_int
-      assert_slot_to_reg( 20 , "id_factory_.next_object" , 1 , "id_factory_.next_object.next_integer")
+      assert_slot_to_reg( 20 , :r3 , 1 , :r2)
     end
     def test_move_next_back_to_factory
-      assert_reg_to_slot( 21 , "id_factory_.next_object.next_integer" , "id_factory_" , 2)
+      assert_reg_to_slot( 21 , :r2 , :r1 , 2)
     end
   end
 end
diff --git a/test/risc/interpreter/calling/test_minus.rb b/test/risc/interpreter/calling/test_minus.rb
index dde868d3..00ba8224 100644
--- a/test/risc/interpreter/calling/test_minus.rb
+++ b/test/risc/interpreter/calling/test_minus.rb
@@ -26,16 +26,16 @@ module Risc
        assert_equal 1 , get_return
     end
     def test_op
-      assert_operator 26  , :- , "message.receiver.data_1" , "message.arg1.data_1" , "op_-_"
+      assert_operator 26  , :- , :r2 , :r4 , :r1
       assert_equal 1 , @interpreter.get_register(@instruction.result)
-      assert_equal 6 , @interpreter.get_register(:"message.receiver.data_1")
-      assert_equal 5 , @interpreter.get_register(:"message.arg1.data_1")
+      assert_equal 6 , @interpreter.get_register(:r2)
+      assert_equal 5 , @interpreter.get_register(:r4)
     end
     def test_return
       ret = main_ticks(46)
       assert_equal FunctionReturn ,  ret.class
-      assert_equal :"message.return_address" ,  ret.register.symbol
-      assert_equal 36572 ,  @interpreter.get_register(ret.register).value
+      assert_equal :r1 ,  ret.register.symbol
+      assert_equal 36540 ,  @interpreter.get_register(ret.register).value
     end
   end
 end
diff --git a/test/risc/interpreter/calling/test_mod.rb b/test/risc/interpreter/calling/test_mod.rb
index b70e4f19..09919045 100644
--- a/test/risc/interpreter/calling/test_mod.rb
+++ b/test/risc/interpreter/calling/test_mod.rb
@@ -26,9 +26,9 @@ module Risc
     end
 
     def test_op
-      assert_operator 22 , :>>,  "message.receiver.data_1" , "integer_1" , "op_>>_"
-      assert_equal 2 , @interpreter.get_register(:integer_1)
-      assert_equal 9 , @interpreter.get_register(:"message.receiver.data_1")
+      assert_operator 22 , :>>,  :r2 , :r1 , :r4
+      assert_equal 2 , @interpreter.get_register(:r1)
+      assert_equal 9 , @interpreter.get_register(:r2)
     end
   end
 end
diff --git a/test/risc/interpreter/calling/test_mult.rb b/test/risc/interpreter/calling/test_mult.rb
index bceef51e..df110163 100644
--- a/test/risc/interpreter/calling/test_mult.rb
+++ b/test/risc/interpreter/calling/test_mult.rb
@@ -30,9 +30,9 @@ module Risc
       assert @interpreter.flags[:zero]
     end
     def test_op
-      assert_operator 26 , :*,  "message.receiver.data_1" , "message.arg1.data_1" , "op_*_"
-      assert_equal 2147483648 , @interpreter.get_register(:"message.arg1.data_1")
-      assert_equal 2147483648 , @interpreter.get_register(:"message.receiver.data_1")
+      assert_operator 26 , :*,  :r2 , :r4 , :r1
+      assert_equal 2147483648 , @interpreter.get_register(:r4)
+      assert_equal 2147483648 , @interpreter.get_register(:r2)
     end
     def test_overflow
       main_ticks( 26 )
diff --git a/test/risc/interpreter/calling/test_plus.rb b/test/risc/interpreter/calling/test_plus.rb
index 41057e38..80538553 100644
--- a/test/risc/interpreter/calling/test_plus.rb
+++ b/test/risc/interpreter/calling/test_plus.rb
@@ -26,14 +26,14 @@ module Risc
        assert_equal 10 , get_return
     end
     def test_op
-      assert_operator 26, :+ ,  "message.receiver.data_1" ,  "message.arg1.data_1" , "op_+_"
+      assert_operator 26, :+ ,  :r2 ,  :r4 , :r1
       assert_equal 10 , @interpreter.get_register(@instruction.result.symbol)
     end
     def test_move_res_to_int
-      assert_reg_to_slot( 27 , "op_+_" , "id_factory_.next_object" , 2)
+      assert_reg_to_slot( 27 , :r1 , :r3 , 2)
     end
     def test_move_int_to_reg
-      assert_reg_to_slot( 28 , "id_factory_.next_object" , :message , 5)
+      assert_reg_to_slot( 28 , :r3 , :r0 , 5)
     end
   end
 end
diff --git a/test/risc/interpreter/calling/test_puts.rb b/test/risc/interpreter/calling/test_puts.rb
index 3451d9f5..e60eb513 100644
--- a/test/risc/interpreter/calling/test_puts.rb
+++ b/test/risc/interpreter/calling/test_puts.rb
@@ -11,7 +11,7 @@ module Risc
     end
 
     def test_chain
-      #show_main_ticks # get output of what is
+      show_main_ticks # get output of what is
       check_main_chain [LoadConstant, SlotToReg, RegToSlot, LoadConstant, SlotToReg, #5
                  RegToSlot, LoadConstant, SlotToReg, RegToSlot, SlotToReg, #10
                  FunctionCall, LoadConstant, LoadConstant, SlotToReg, OperatorInstruction, #15
@@ -48,7 +48,7 @@ module Risc
     end
 
     def test_move_sys_return
-      assert_transfer(26, :syscall_1 ,:integer_tmp)
+      assert_transfer(26, :r0 ,:r1)
       assert_equal 11 , @interpreter.get_register(:integer_tmp)
     end
     def test_restore_message
diff --git a/test/risc/interpreter/test_dynamic_call.rb b/test/risc/interpreter/test_dynamic_call.rb
index 2e9232f3..6b6a6d07 100644
--- a/test/risc/interpreter/test_dynamic_call.rb
+++ b/test/risc/interpreter/test_dynamic_call.rb
@@ -12,7 +12,7 @@ module Risc
 
     def test_chain
       #show_main_ticks # get output of what is
-      check_main_chain  [LoadConstant, RegToSlot, LoadConstant, SlotToReg, SlotToReg, #5
+      check_main_chain [LoadConstant, RegToSlot, LoadConstant, SlotToReg, SlotToReg, #5
                  SlotToReg, OperatorInstruction, IsZero, SlotToReg, SlotToReg, #10
                  LoadConstant, RegToSlot, LoadConstant, LoadConstant, SlotToReg, #15
                  SlotToReg, LoadConstant, OperatorInstruction, IsZero, SlotToReg, #20
@@ -26,7 +26,8 @@ module Risc
                  Branch, SlotToReg, RegToSlot, SlotToReg, SlotToReg, #60
                  FunctionReturn, SlotToReg, RegToSlot, Branch, SlotToReg, #65
                  SlotToReg, RegToSlot, SlotToReg, SlotToReg, FunctionReturn, #70
-                 Transfer, SlotToReg, SlotToReg, Transfer ,Syscall, NilClass,] #75
+                 Transfer, SlotToReg, SlotToReg, Transfer, Syscall, #75
+                 NilClass,] #80
        assert_equal ::Integer , get_return.class
        assert_equal 1 , get_return
     end
diff --git a/test/risc/interpreter/while/test_while_simple.rb b/test/risc/interpreter/while/test_while_simple.rb
index e6119cbd..b1746bed 100644
--- a/test/risc/interpreter/while/test_while_simple.rb
+++ b/test/risc/interpreter/while/test_while_simple.rb
@@ -18,7 +18,7 @@ module Risc
                  SlotToReg, RegToSlot, SlotToReg, SlotToReg, FunctionReturn, #25
                  Transfer, SlotToReg, SlotToReg, Transfer, Syscall, #30
                  NilClass,] #35
-      assert_kind_of NilClass , get_return
+      assert_kind_of Parfait::NilClass , get_return
     end
     def test_load_false_const
       load = main_ticks(1)
diff --git a/test/risc/test_interpreter.rb b/test/risc/test_interpreter.rb
index b5474b2a..339fe706 100644
--- a/test/risc/test_interpreter.rb
+++ b/test/risc/test_interpreter.rb
@@ -54,7 +54,7 @@ module Risc
     end
     def test_pc
       @interpreter.tick
-      assert_equal t = 36136 , @interpreter.pc
+      assert_equal t = 36104 , @interpreter.pc
       @interpreter.tick
       assert_equal t + 4 , @interpreter.pc
     end
diff --git a/test/support/risc_interpreter.rb b/test/support/risc_interpreter.rb
index 562ddb74..2b06cdf3 100644
--- a/test/support/risc_interpreter.rb
+++ b/test/support/risc_interpreter.rb
@@ -48,8 +48,8 @@ module Risc
     end
 
     def get_return
-      assert_equal Parfait::Message , @interpreter.get_register(:saved_message).class
-      @interpreter.get_register(:syscall_1)
+      assert_equal Parfait::Message , @interpreter.get_register(:r15).class
+      @interpreter.get_register(:r0)
     end
 
     # do as many as given ticks in the main, ie main_at more
@@ -98,7 +98,7 @@ module Risc
     # get the return from the message (not exit code)
     # exit code must be int
     def get_message_return
-      @interpreter.get_register(:message).return_value
+      @interpreter.get_register(:r15).return_value
     end
 
     # wrap the input so it is a main, compile and run it