diff --git a/lib/risc/interpreter.rb b/lib/risc/interpreter.rb
index 32874ef6..b18bab9c 100644
--- a/lib/risc/interpreter.rb
+++ b/lib/risc/interpreter.rb
@@ -256,6 +256,7 @@ module Risc
       false
     end
 
+    # execute the given system call, only putstring and exit really
     def execute_Syscall
       name = @instruction.name
       ret_value = 0
@@ -274,8 +275,12 @@ module Risc
       true
     end
 
+    # get the return after system exit. exit_sequence expects the last return to
+    # be an int and reduces that, so that is returned
+    # the value is reduced to 8 bits, because that is what linux does
     def get_sys_return
       val = get_register( std_reg(:syscall_1) ) # syscalls return into syscall_1
+      val & 0xFF
     end
 
     def run_all
diff --git a/test/mains/README.md b/test/mains/README.md
index 36c39815..729f06a5 100644
--- a/test/mains/README.md
+++ b/test/mains/README.md
@@ -2,34 +2,45 @@
 
 Test methods by their output and exit codes (return, since it is the main).
 
-There are only two tests here (plus one, see below), one for interpreter, one for arm.
-Both run the same tests. The actual ruby code that is run is in the source dir.
-Test methods are generated, one for each source file.
+Every test here is tested first as an Interpreter test, and then as binary (arm).
 
-## Files
 
-File names follow [order,name,stdout,exitcode] joined by _ pattern.
-Stdout may be left blank, but exit code must be supplied.
+## Setup and assert
 
-The order number is some number giving the difficulty of the test, higher is more.
-The first digit represents how many external methods the code relies on, the second
-is some general indicator, ie recursive is more difficult than not, syscalls more than
-normal calls, if or while more than nothing etc.
+The setup require the @input variable to hold the code. This is usually renerated with
+as_main or similar helper.
 
-## Arm
+The @preload may be set to load any of the Macros, so one can actually use methods.
+Otherwise the only methods are the ones you code
 
-Obviously the arm tests need an arm platform. This may be defined by ARM_HOST,
-eg for simulated ARM_HOST=localhost
+The assert_result takes the exit code and std out. It runs both interpreter and arm,
+in that order.
 
-Also port and user may be specified with ARM_PORT and ARM_USER , they default to
-2222 and pi if left blank.
-SSH keys must be set up so no passwords are required (and the users private key may
-  not be password protected)
+### Interpreter
 
-## Developing
+The interpreter is for the most part like another platform. Everything up to the
+creation of binaries is the same. The Linker object get's passed to the
+Interpreter which runs the code to the end, and returns return code and stdout.
 
-Since the Framework always runs all tests, it is a little cumbersome for developing
-a single new test. Since all get run and it is slow.
+If this passes, arm is run.
 
-To develop the next test, one can edit test_new.rb . Once it runs on the interpreter,
-move the changes to a source file and revert test_new changes.
+### Arm
+
+Arm is actually only run if:
+- you set TEST_ALL  (as is done in test/test_all)
+- you set TEST_ARM
+
+AND it requires that you have qemu set up correctly. But given all that, it:
+- creates a binary from the code (mains.o), which is linked to a.out
+- runs the binary
+- captures return code and stdout and returns
+
+Obviously Interpreter AND Arm need to return same codes, the one the assert specifies.
+
+## Status
+
+I have moved most of the risc/interpreter code here, which means we now have over 50
+binary tests.
+
+Next i will recreate the file based tests in a better way to integrate with the
+current style.
diff --git a/test/mains/test_int_math.rb b/test/mains/test_int_math.rb
index 08282ed3..721c1400 100644
--- a/test/mains/test_int_math.rb
+++ b/test/mains/test_int_math.rb
@@ -18,7 +18,7 @@ module Mains
       def test_minus_neg
         @preload = "Integer.minus"
         run_main_return "5 - 15"
-#        assert_result( -10 , "")
+        assert_result( 246 , "")
       end
       def test_rshift
         @preload = "Integer.rs"
@@ -28,7 +28,7 @@ module Mains
       def test_lshift
         @preload = "Integer.ls"
         run_main_return "#{2**8} << 3"
-#        assert_result 2**11 , ""
+        assert_result 0 , ""
       end
       def test_div10
         @preload = "Integer.div10"
diff --git a/test/mains/test_while.rb b/test/mains/test_while.rb
index fc6d877f..35029e09 100644
--- a/test/mains/test_while.rb
+++ b/test/mains/test_while.rb
@@ -18,7 +18,7 @@ module Mains
 
     def test_while_simple
       @input = as_main 'a = true; while( a ); a = false;end;return a'
-#      assert_result 4 , ""
+      assert_result 0 , ""
     end
 
   end
diff --git a/test/risc/interpreter/builtin/README.md b/test/risc/interpreter/builtin/README.md
deleted file mode 100644
index 01d4c254..00000000
--- a/test/risc/interpreter/builtin/README.md
+++ /dev/null
@@ -1,5 +0,0 @@
-# Builtin Testing
-
-Basically test builtin methods by their output.
-
-Currently through Interpreter only
diff --git a/test/risc/interpreter/builtin/test_int_cmp.rb b/test/risc/interpreter/builtin/test_int_cmp.rb
deleted file mode 100644
index 2adbf11f..00000000
--- a/test/risc/interpreter/builtin/test_int_cmp.rb
+++ /dev/null
@@ -1,61 +0,0 @@
-require_relative "../helper"
-
-module Risc
-  module Macro
-    class IntCmp < Minitest::Test
-      include Ticker
-      def setup
-        @preload = [:le,:ge,:gt,:lt].collect{|op| "Integer.#{op}"}.join(";")
-      end
-
-      def test_smaller_true
-        run_main_return "4 < 5"
-        assert_equal Parfait::TrueClass , get_message_return.class
-      end
-      def test_smaller_false
-        run_main_return "6 < 5"
-        assert_equal Parfait::FalseClass , get_message_return.class
-      end
-      def test_smaller_false_same
-        run_main_return "5 < 5"
-        assert_equal Parfait::FalseClass , get_message_return.class
-      end
-      def test_larger_true
-        run_main_return "5 > 4"
-        assert_equal Parfait::TrueClass , get_message_return.class
-      end
-      def test_larger_false
-        run_main_return "5 > 6"
-        assert_equal Parfait::FalseClass , get_message_return.class
-      end
-      def test_larger_false_same
-        run_main_return "5 > 5"
-        assert_equal Parfait::FalseClass , get_message_return.class
-      end
-      def test_smaller_or_true
-        run_main_return "4 <= 5"
-        assert_equal Parfait::TrueClass , get_message_return.class
-      end
-      def test_smaller_or_false
-        run_main_return "6 <= 5"
-        assert_equal Parfait::FalseClass , get_message_return.class
-      end
-      def test_smaller_or_same
-        run_main_return "5 <= 5"
-        assert_equal Parfait::TrueClass , get_message_return.class
-      end
-      def test_larger_or_true
-        run_main_return "5 >= 4"
-        assert_equal Parfait::TrueClass , get_message_return.class
-      end
-      def test_larger_or_false
-        run_main_return "5 >= 6"
-        assert_equal Parfait::FalseClass , get_message_return.class
-      end
-      def test_larger_or_same
-        run_main_return "5 >= 5"
-        assert_equal Parfait::TrueClass , get_message_return.class
-      end
-    end
-  end
-end
diff --git a/test/risc/interpreter/test_while_simple.rb b/test/risc/interpreter/test_while_simple.rb
index 6056d082..f3119fa3 100644
--- a/test/risc/interpreter/test_while_simple.rb
+++ b/test/risc/interpreter/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 Parfait::NilClass , get_return
+      assert_equal 0 , 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 96330fde..a6c19caa 100644
--- a/test/risc/test_interpreter.rb
+++ b/test/risc/test_interpreter.rb
@@ -43,6 +43,17 @@ module Risc
       assert_equal 5 , @interpreter.get_sys_return
     end
   end
+  class TestInterpreterRetBig < MiniTest::Test
+    include Ticker
+    def setup
+      @string_input = as_main("return 257")
+      super
+    end
+    def test_return_value
+      @interpreter.run_all
+      assert_equal 1 , @interpreter.get_sys_return
+    end
+  end
   class TestInterpreterTicks < MiniTest::Test
     include Ticker
     def setup