diff --git a/lib/arm/arm_machine.rb b/lib/arm/arm_machine.rb
index ed849a62..2f178c9b 100644
--- a/lib/arm/arm_machine.rb
+++ b/lib/arm/arm_machine.rb
@@ -29,14 +29,14 @@ module Arm
         end
       end
     end
-  
+    
     def word_load value , reg
       e = Vm::Block.new("load_#{value}")
       e.add_code( MoveInstruction.new( :left => reg , :right => value ) )
     end
     def function_call call
       raise "Not FunctionCall #{call.inspect}" unless call.is_a? Vm::FunctionCall
-      bl( :function => call.function )
+      bl( :left => call.function )
     end
 
     def main_entry
@@ -47,7 +47,7 @@ module Arm
     end
     def syscall num
       mov( :left => 7 , :right => num ) 
-      swi( {} )
+      swi( :left => 0 )
     end
   end
 end
\ No newline at end of file
diff --git a/lib/arm/assembler.rb b/lib/arm/assembler.rb
index b095f2bc..70915deb 100644
--- a/lib/arm/assembler.rb
+++ b/lib/arm/assembler.rb
@@ -1,10 +1,10 @@
-require 'asm/nodes'
-require 'asm/block'
+require 'arm/nodes'
+require 'arm/block'
 require 'stream_reader'
 require 'stringio'
-require "asm/string_literal"
+require "arm/string_literal"
 
-module Asm
+module Arm
   
   # Assembler is the the top-level of the code hierachy, except it is not derived from code
   # instead a Assembler is a list of blocks (and string constants)
@@ -43,7 +43,7 @@ module Asm
     def add_string str
       code = @string_table[str]
       return code if code
-      data = Asm::StringLiteral.new(str)
+      data = Arm::StringLiteral.new(str)
       @string_table[str] = data
     end
 
diff --git a/lib/arm/assembly_error.rb b/lib/arm/assembly_error.rb
deleted file mode 100644
index c3d7dd33..00000000
--- a/lib/arm/assembly_error.rb
+++ /dev/null
@@ -1,8 +0,0 @@
-module Asm
-  class AssemblyError < StandardError
-    def initialize(message)
-      super(message)
-    end
-  end
-end
-  
\ No newline at end of file
diff --git a/lib/arm/block.rb b/lib/arm/block.rb
index ab783b6a..0f7168f7 100644
--- a/lib/arm/block.rb
+++ b/lib/arm/block.rb
@@ -3,7 +3,7 @@ require_relative 'stack_instruction'
 require_relative 'logic_instruction'
 require_relative 'memory_instruction'
 
-module Asm
+module Arm
   
   class Code ; end
   
@@ -48,76 +48,6 @@ module Asm
     end
     attr_reader :name
 
-    ArmMachine::REGISTERS.each do |reg , number|
-      define_method(reg) { Asm::Register.new(reg , number) }
-    end
-
-    def instruction(clazz, opcode , condition_code , update_status , *args)
-      arg_nodes = []
-      args.each do |arg|
-        if (arg.is_a?(Asm::Register))
-          arg_nodes << arg
-        elsif (arg.is_a?(Integer))
-          arg_nodes << Asm::NumLiteral.new(arg)
-        elsif (arg.is_a?(String))
-          arg_nodes << @program.add_string(arg)
-        elsif (arg.is_a?(Asm::Block))
-          arg_nodes << arg
-        elsif (arg.is_a?(Symbol))
-          block = @program.get_block arg
-          arg_nodes << block
-        else
-          raise "Invalid argument #{arg.inspect} for instruction"
-        end
-      end
-      add_code clazz.new(opcode , condition_code , update_status , arg_nodes)
-    end
-    
-    
-    def self.define_instruction(inst , clazz )
-      define_method(inst) do |*args|
-        instruction clazz , inst , :al , 0 , *args
-      end
-      define_method("#{inst}s") do |*args|
-        instruction clazz , inst , :al , 1 , *args
-      end
-      ArmMachine::COND_CODES.keys.each do |suffix|
-        define_method("#{inst}#{suffix}") do |*args|
-          instruction clazz , inst , suffix , 0 , *args
-        end
-        define_method("#{inst}s#{suffix}") do |*args|
-          instruction clazz , inst , suffix , 1 , *args
-        end
-      end
-    end
-
-    [:push, :pop].each do |inst|
-      define_instruction(inst , StackInstruction)
-    end
-
-    [:adc, :add, :and, :bic, :eor, :orr, :rsb, :rsc, :sbc, :sub].each do |inst|
-      define_instruction(inst , LogicInstruction)
-    end
-    [:mov, :mvn].each do |inst|
-      define_instruction(inst , MoveInstruction)
-    end
-    [:cmn, :cmp, :teq, :tst].each do |inst|
-      define_instruction(inst , CompareInstruction)
-    end
-    [:strb, :str , :ldrb, :ldr].each do |inst|
-      define_instruction(inst , MemoryInstruction)
-    end
-    [:b, :bl , :swi].each do |inst|
-      define_instruction(inst , CallInstruction)
-    end
-
-    # codeing a block fixes it's position in the stream. 
-    # You must call with a block, which is instance_eval'd and provides the actual code for the block
-    def code &block
-      @program.add_block self
-      self.instance_eval block 
-    end
-
     # length of the codes. In arm it would be the length * 4
     # (strings are stored globally in the Assembler)
     def length 
diff --git a/lib/arm/call_instruction.rb b/lib/arm/call_instruction.rb
index 4b13fd18..1a1dd946 100644
--- a/lib/arm/call_instruction.rb
+++ b/lib/arm/call_instruction.rb
@@ -1,4 +1,5 @@
 require_relative "instruction"
+require_relative "nodes"
 
 module Arm
   # There are only three call instructions in arm branch (b), call (bl) and syscall (swi)
@@ -14,33 +15,54 @@ module Arm
   # Registers 0-6 hold the call values as for a normal c call
   
   class CallInstruction < Vm::CallInstruction
+    include Arm::Constants
+    
+    # arm intrucioons are pretty sensible, and always 4 bytes (thumb not supported)
+    def length
+      4
+    end
+
+    def initialize(options)
+      super(options)
+      @update_status_flag = 0
+      @condition_code = :al
+      @opcode = options[:opcode]
+      @args = [options[:left] , options[:right] , options[:extra]]
+      @operand = 0
+    end
     
     def assemble(io)
-      case opcode
+      case @opcode
       when :b, :bl
-        arg = args[0]
-        if arg.is_a? Block
-          diff = arg.position - self.position - 8
-          arg = NumLiteral.new(diff)
+        arg = @args[0]
+        if( arg.is_a? Fixnum ) #HACK to not have to change the code just now
+          arg = Arm::NumLiteral.new( arg )
         end
-        if (arg.is_a?(Asm::NumLiteral))
+        if arg.is_a? Vm::Code
+          diff = arg.position - self.position - 8
+          arg = Arm::NumLiteral.new(diff)
+        end
+        if (arg.is_a?(Arm::NumLiteral))
           jmp_val = arg.value >> 2
           packed = [jmp_val].pack('l')
           # signed 32-bit, condense to 24-bit
           # TODO add check that the value fits into 24 bits
           io << packed[0,3]
         else
-          raise "else not coded #{arg.inspect}"
+          raise "else not coded #{inspect}"
         end
         io.write_uint8 OPCODES[opcode] | (COND_CODES[@condition_code] << 4)
       when :swi
-        arg = args[0]
-        if (arg.is_a?(Asm::NumLiteral))
+        arg = @args[0]
+        if( arg.is_a? Fixnum ) #HACK to not have to change the code just now
+          arg = Arm::NumLiteral.new( arg )
+        end
+        if (arg.is_a?(Arm::NumLiteral))
           packed = [arg.value].pack('L')[0,3]
           io << packed
           io.write_uint8 0b1111 | (COND_CODES[@condition_code] << 4)
         else
-          raise Asm::AssemblyError.new("invalid operand argument expected literal not #{arg}")
+          raise "invalid operand argument expected literal not #{arg} #{inspect}"
         end
       end
     end
diff --git a/lib/arm/constants.rb b/lib/arm/constants.rb
index 9c0bb818..e5dd9e1d 100644
--- a/lib/arm/constants.rb
+++ b/lib/arm/constants.rb
@@ -51,11 +51,13 @@ module Arm
                   'v6' => 9, 'rfp' => 9, 'sl' => 10, 'fp' => 11, 'ip' => 12, 'sp' => 13,
                   'lr' => 14, 'pc' => 15 }
     def reg name
-      raise "no such register #{reg}" unless REGISTERS[name]
-      Asm::Register.new(name , REGISTERS[name])
+      code = reg_code name
+      raise "no such register #{name}" unless code
+      Arm::Register.new(name.to_sym , code )
+    end
+    def reg_code name
+      REGISTERS[name.to_s]
     end
-                      
-            
 
    def calculate_u8_with_rr(arg)
      parts = arg.value.to_s(2).rjust(32,'0').scan(/^(0*)(.+?)0*$/).flatten
diff --git a/lib/arm/instruction.rb b/lib/arm/instruction.rb
index 7b408c84..fb159e33 100644
--- a/lib/arm/instruction.rb
+++ b/lib/arm/instruction.rb
@@ -1,10 +1,7 @@
 require "vm/instruction"
 require_relative "constants"
 
-  Vm::Instruction.class_eval do
-    include Arm::Constants
-
-    COND_POSTFIXES = Regexp.union( Arm::Constants::COND_CODES.keys.collect{|k|k.to_s} ).source
+class Saved
 
     def initializ(opcode , condition_code , update_status , args)
       @update_status_flag = update_status
diff --git a/lib/arm/logic_instruction.rb b/lib/arm/logic_instruction.rb
index 1d330715..c2b3795b 100644
--- a/lib/arm/logic_instruction.rb
+++ b/lib/arm/logic_instruction.rb
@@ -1,33 +1,31 @@
 require_relative "instruction"
 
 module Arm
-  # ADDRESSING MODE 1 
-  # Logic ,Maths, Move and compare instructions (last three below)
-  
-  class LogicInstruction < Vm::LogicInstruction
-
-    def initializ(opcode , condition_code , update_status , args)
-      super(opcode , condition_code , update_status , args)
-      @rn = nil
-      @i = 0      
-      @rd = args[0]
-    end
-    attr_accessor :i, :rn, :rd
-
+  module LogicHelper
+    # ADDRESSING MODE 1 
+    # Logic ,Maths, Move and compare instructions (last three below)
     # Build representation for source value 
     def build
-      @rn = args[1]
-      do_build args[2] 
+      @rn = @args[1]
+      do_build @args[2] 
     end
     
+    # arm intrucioons are pretty sensible, and always 4 bytes (thumb not supported)
+    def length
+      4
+    end
+
     #(stays in subclases, while build is overriden to provide different arguments)
     def do_build(arg)      
-      if arg.is_a?(Asm::StringLiteral)
+      if arg.is_a?(Arm::StringLiteral)
         # do pc relative addressing with the difference to the instuction
         # 8 is for the funny pipeline adjustment (ie oc pointing to fetch and not execute)
-        arg = Asm::NumLiteral.new( arg.position - self.position - 8 )
+        arg = Arm::NumLiteral.new( arg.position - self.position - 8 )
       end
-      if (arg.is_a?(Asm::NumLiteral))
+      if( arg.is_a? Fixnum ) #HACK to not have to change the code just now
+        arg = Arm::NumLiteral.new( arg )
+      end
+      if (arg.is_a?(Arm::NumLiteral))
         if (arg.value.fits_u8?)
           # no shifting needed
           @operand = arg.value
@@ -36,28 +34,28 @@ module Arm
           @operand = op_with_rot
           @i = 1
         else
-          raise Asm::AssemblyError.new("cannot fit numeric literal argument in operand #{arg}")
+          raise "cannot fit numeric literal argument in operand #{arg}"
         end
-      elsif (arg.is_a?(Asm::Register))
+      elsif (arg.is_a?(Arm::Register))
         @operand = arg
         @i = 0
-      elsif (arg.is_a?(Asm::Shift))
+      elsif (arg.is_a?(Arm::Shift))
         rm_ref = arg.argument
         @i = 0
         shift_op = {'lsl' => 0b000, 'lsr' => 0b010, 'asr' => 0b100,
                     'ror' => 0b110, 'rrx' => 0b110}[arg.type]
         if (arg.type == 'ror' and arg.value.nil?)
           # ror #0 == rrx
-          raise Asm::AssemblyError.new('cannot rotate by zero', arg)
+          raise "cannot rotate by zero #{arg} #{inspect}"
         end
     
         arg1 = arg.value
-        if (arg1.is_a?(Asm::NumLiteral))
+        if (arg1.is_a?(Arm::NumLiteral))
           if (arg1.value >= 32)
-            raise Asm::AssemblyError.new('cannot shift by more than 31', arg1)
+            raise "cannot shift by more than 31 #{arg1} #{inspect}"
           end
           shift_imm = arg1.value
-        elsif (arg1.is_a?(Asm::Register))
+        elsif (arg1.is_a?(Arm::Register))
           shift_op val |= 0x1;
           shift_imm = arg1.number << 1
         elsif (arg.type == 'rrx')
@@ -66,43 +64,78 @@ module Arm
     
         @operand = rm_ref | (shift_op << 4) | (shift_imm << 4+3)
       else
-        raise Asm::AssemblyError.new("invalid operand argument #{arg.inspect}")
+        raise "invalid operand argument #{arg.inspect}"
       end
     end
 
     def assemble(io)
       build
       instuction_class = 0b00 # OPC_DATA_PROCESSING
-      val = operand.is_a?(Register) ? operand.bits : operand 
-      val |= (rd.bits <<            12)     
-      val |= (rn.bits <<            12+4)   
-      val |= (update_status_flag << 12+4+4)#20 
+      val = @operand.is_a?(Symbol) ? reg_code(@operand) : @operand 
+      val |= (reg_code(@rd) <<            12)     
+      val |= (reg_code(@rn) <<            12+4)   
+      val |= (@update_status_flag << 12+4+4)#20 
       val |= (op_bit_code <<        12+4+4  +1)
-      val |= (i <<                  12+4+4  +1+4) 
+      val |= (@i <<                  12+4+4  +1+4) 
       val |= (instuction_class <<   12+4+4  +1+4+1) 
       val |= (cond_bit_code <<      12+4+4  +1+4+1+2)
       io.write_uint32 val
     end
   end
+  class LogicInstruction < Vm::LogicInstruction
+    include Arm::Constants
+    include LogicHelper
+
+    def initialize(options)
+      super(options) 
+      @update_status_flag = 0
+      @condition_code = :al
+      @opcode = options[:opcode]
+      @args = [options[:left] , options[:right] , options[:extra]]
+      @operand = 0
+
+      @rn = nil
+      @i = 0      
+      @rd = args[0]
+    end
+    attr_accessor :i, :rn, :rd
+
+  end
   class CompareInstruction < Vm::CompareInstruction
-    def initialize(opcode , condition_code , update_status , args)
-      super(opcode , condition_code , update_status , args)
+    def initialize(options)
+      super(options) 
+      @condition_code = :al
+      @opcode = options[:opcode]
+      @args = [options[:left] , options[:right] , options[:extra]]
+      @operand = 0
+      @i = 0      
       @update_status_flag = 1
-      @rn = args[0]
-      @rd = reg "r0"
+      @rn = @args[0]
+      @rd = :r0
     end
     def build 
       do_build args[1]
     end
   end
   class MoveInstruction < Vm::MoveInstruction
-    def initializ(opcode , condition_code , update_status , args)
-      super(opcode , condition_code , update_status , args)
-      @rn = reg "r0" # register zero = zero bit pattern
+    include Arm::Constants
+    include LogicHelper
+
+    def initialize(options) 
+      super(options)
+      @update_status_flag = 0
+      @condition_code = :al
+      @opcode = options[:opcode]
+      @args = [options[:left] , options[:right] , options[:extra]]
+      @operand = 0
+
+      @i = 0      
+      @rd = @args[0]
+      @rn = :r0 # register zero = zero bit pattern
     end
     
     def build
-      do_build args[1]
+      do_build @args[1]
     end
   end
 end
\ No newline at end of file
diff --git a/lib/arm/memory_instruction.rb b/lib/arm/memory_instruction.rb
index 7fc33b30..88ef6b29 100644
--- a/lib/arm/memory_instruction.rb
+++ b/lib/arm/memory_instruction.rb
@@ -1,10 +1,11 @@
-require "asm/nodes"
+require_relative "nodes"
 require_relative "instruction"
 
 module Arm
   # ADDRESSING MODE 2
   # Implemented: immediate offset with offset=0
   class MemoryInstruction < Vm::MemoryInstruction
+    include Arm::Constants
 
     def initialize(opcode , condition_code , update_status , args)
       super(opcode , condition_code , update_status , args)
@@ -20,6 +21,11 @@ module Arm
     attr_accessor :i, :pre_post_index, :add_offset,
                   :byte_access, :w, :is_load, :rn, :rd
 
+    # arm intrucioons are pretty sensible, and always 4 bytes (thumb not supported)
+    def length
+      4
+    end
+                  
     # Build representation for target address
     def build
       if( @is_load )
@@ -30,7 +36,7 @@ module Arm
         arg = args[0]
       end
       #str / ldr are _serious instructions. With BIG possibilities not half are implemented
-      if (arg.is_a?(Asm::Register))
+      if (arg.is_a?(Arm::Register))
         @rn = arg
         if(arg.offset != 0) 
           @operand = arg.offset
@@ -42,16 +48,16 @@ module Arm
             @add_offset = 1
           end
           if (@operand.abs > 4095)
-            raise Asm::AssemblyError.new("reference offset too large/small (max 4095) #{argr.right}" )
+            raise "reference offset too large/small (max 4095) #{arg} #{inspect}"
           end
         end
-      elsif (arg.is_a?(Asm::Label) or arg.is_a?(Asm::NumLiteral))
+      elsif (arg.is_a?(Arm::Label) or arg.is_a?(Arm::NumLiteral))
         @pre_post_index = 1
         @rn = pc
         @use_addrtable_reloc = true
         @addrtable_reloc_target = arg
       else
-        raise Asm::AssemblyError.new("invalid operand argument #{arg.inspect}")
+        raise "invalid operand argument #{arg.inspect} #{inspect}"
       end
     end
 
diff --git a/lib/arm/nodes.rb b/lib/arm/nodes.rb
index 7297019b..112a6f52 100644
--- a/lib/arm/nodes.rb
+++ b/lib/arm/nodes.rb
@@ -1,4 +1,4 @@
-module Asm
+module Arm
 
   class Shift 
     attr_accessor :type, :value, :argument
@@ -30,7 +30,7 @@ module Asm
     attr_accessor :registers
     def initialize regs
       @registers = regs
-      regs.each{ |reg| raise  "not a reg #{sym} , #{reg}" unless reg.is_a?(Asm::Register) }
+      regs.each{ |reg| raise  "not a reg #{sym} , #{reg}" unless reg.is_a?(Arm::Register) }
     end
   end
 
diff --git a/lib/arm/stack_instruction.rb b/lib/arm/stack_instruction.rb
index be106fe1..2441a85e 100644
--- a/lib/arm/stack_instruction.rb
+++ b/lib/arm/stack_instruction.rb
@@ -3,9 +3,21 @@ require_relative "instruction"
 module Arm
   # ADDRESSING MODE 4
   class StackInstruction < Vm::StackInstruction
+    include Arm::Constants
+
+    # arm intrucioons are pretty sensible, and always 4 bytes (thumb not supported)
+    def length
+      4
+    end
+
+    def initialize(options)
+      super(options) 
+      @update_status_flag = 0
+      @condition_code = :al
+      @opcode = options[:opcode]
+      @args = [options[:left] , options[:right] , options[:extra]]
+      @operand = 0
 
-    def initializ(opcode , condition_code , update_status , args)
-      super(opcode , condition_code , update_status , args)
       @update_status_flag= 0
       @rn = reg "r0" # register zero = zero bit pattern
       # downward growing, decrement before memory access
@@ -51,7 +63,7 @@ module Arm
           @operand |= (1 << reg.bits)
         end
       else
-        raise Asm::AssemblyError.new("invalid operand argument  #{args.inspect}")
+        raise "invalid operand argument  #{args.inspect}"
       end
     end
   end
diff --git a/lib/arm/string_literal.rb b/lib/arm/string_literal.rb
index 36f54800..04a0d908 100644
--- a/lib/arm/string_literal.rb
+++ b/lib/arm/string_literal.rb
@@ -1,6 +1,6 @@
-require_relative "../vm/code"
+require "vm/code"
 
-module Asm
+module Arm
   # The name really says it all.
   # The only interesting thing is storage.
   # Currently string are stored "inline" , ie in the code segment. 
diff --git a/lib/crystal.rb b/lib/crystal.rb
index 354862fb..7ef6a116 100644
--- a/lib/crystal.rb
+++ b/lib/crystal.rb
@@ -1,6 +1,6 @@
 require 'parslet'
 
-require "asm/assembler"
+require "arm/assembler"
 require "elf/object_writer"
 require 'parser/composed'
 require 'parser/transform'
diff --git a/lib/vm/code.rb b/lib/vm/code.rb
index 64c3c5b1..85271cc1 100644
--- a/lib/vm/code.rb
+++ b/lib/vm/code.rb
@@ -13,7 +13,7 @@ module Vm
     
     # set the position to zero, will have to reset later
     def initialize
-      @position = 0
+      @address = 0
     end
 
     # the position in the stream. Think of it as an address if you want. The difference is small.
diff --git a/test/test_runner.rb b/test/test_runner.rb
index e1fcbd7f..8aa8adf4 100644
--- a/test/test_runner.rb
+++ b/test/test_runner.rb
@@ -33,8 +33,8 @@ class TestRunner < MiniTest::Test
 
     assembly = program.assemble(StringIO.new)
 
-    writer.set_text assembly
-    writer.save("#{file}_test.o")    
+    writer.set_text assembly.string
+    writer.save(file.gsub(".rb" , ".o"))
 
     puts program.to_yaml
   end