diff --git a/Rakefile b/Rakefile
index 275d7ff..a80fba8 100644
--- a/Rakefile
+++ b/Rakefile
@@ -5,3 +5,8 @@ Rake::TestTask.new do |t|
   t.pattern = 'test/test*.rb'
 end
 
+
+##  Check the syntax of all ruby files
+task :syntax do |t|
+  sh "find . -name *.rb -type f -exec ruby -c {} \\; -exec echo {} \\;"
+end
diff --git a/lib/n65.rb b/lib/n65.rb
index 70fda67..2f1e7d8 100644
--- a/lib/n65.rb
+++ b/lib/n65.rb
@@ -43,6 +43,7 @@ module N65
       assembler.fulfill_promises
       puts " Done." unless options[:quiet]
 
+      ##  Optionally write out a symbol map
       if options[:write_symbol_table]
         print "Writing symbol table to #{output_file}.yaml..." unless options[:quiet]
         File.open("#{output_file}.yaml", 'w') do |fp|
@@ -51,6 +52,15 @@ module N65
         puts "Done." unless options[:quiet]
       end
 
+      ##  Optionally write out cycle count for subroutines
+      if options[:cycle_count]
+        print "Writing subroutine cycle counts to #{output_file}.cycles.yaml..." unless options[:quiet]
+        File.open("#{output_file}.cycles.yaml", 'w') do |fp|
+          fp.write(assembler.symbol_table.export_cycle_count_yaml)
+        end
+        puts "Done." unless options[:quiet]
+      end
+
       ##  Emit the complete binary ROM
       rom = assembler.emit_binary_rom
       File.open(output_file, 'w') do |fp|
@@ -111,6 +121,15 @@ module N65
       unless parsed_object.nil?
         exec_result = parsed_object.exec(self)
 
+        ##  TODO
+        ##  I could perhaps keep a tally of cycles used per top level scope here
+        if parsed_object.respond_to?(:cycles)
+          #puts "Line: #{line}"
+          #puts "Cycles #{parsed_object.cycles}"
+          #puts "Sym: #{@symbol_table.scope_stack}"
+          @symbol_table.add_cycles(parsed_object.cycles)
+        end
+
         ##  If we have returned a promise save it for the second pass
         @promises << exec_result if exec_result.kind_of?(Proc)
       end
diff --git a/lib/n65/directives/bytes.rb b/lib/n65/directives/bytes.rb
index 4418101..808c6aa 100644
--- a/lib/n65/directives/bytes.rb
+++ b/lib/n65/directives/bytes.rb
@@ -59,7 +59,7 @@ module N65
       promise = assembler.with_saved_state do |saved_assembler|
         @bytes_array.map! do |byte|
           case byte
-          when Fixnum
+          when Integer
             byte
           when String
             saved_assembler.symbol_table.resolve_symbol(byte)
@@ -77,7 +77,7 @@ module N65
         ##  And just write 0xDE for a placeholder
         placeholder_bytes = @bytes_array.map do |byte|
           case bytes
-          when Fixnum
+          when Integer
             byte
           when String
             0xDE
diff --git a/lib/n65/front_end.rb b/lib/n65/front_end.rb
index 6801bff..4493cda 100644
--- a/lib/n65/front_end.rb
+++ b/lib/n65/front_end.rb
@@ -11,7 +11,7 @@ module N65
     ####
     ##  Initialize with ARGV commandline
     def initialize(argv)
-      @options = {output_file: nil, write_symbol_table: false, quiet: false}
+      @options = {output_file: nil, write_symbol_table: false, quiet: false, cycle_count: false}
       @argv = argv.dup
     end
 
@@ -57,6 +57,7 @@ module N65
       N65::Assembler.from_file(input_file, @options)
     end
 
+
     private
 
     ####
@@ -73,6 +74,10 @@ module N65
           @options[:write_symbol_table] = true
         end
 
+        opts.on('-c', '--cycles', 'Outputs a cycle count yaml document') do
+          @options[:cycle_count] = true
+        end
+
         opts.on('-q', '--quiet', 'No output on success') do
           @options[:quiet] = true
         end
diff --git a/lib/n65/instruction.rb b/lib/n65/instruction.rb
index b0ea4b8..00dfac6 100644
--- a/lib/n65/instruction.rb
+++ b/lib/n65/instruction.rb
@@ -6,7 +6,7 @@ module N65
   ####
   ##  Represents a single 6502 Instruction
   class Instruction
-    attr_reader :op, :arg, :mode, :hex, :description, :length, :cycle, :boundry_add, :flags, :address
+    attr_reader :op, :arg, :mode, :hex, :description, :length, :cycles, :boundry_add, :flags, :address
 
     ##  Custom Exceptions
     class InvalidInstruction < StandardError; end
diff --git a/lib/n65/symbol_table.rb b/lib/n65/symbol_table.rb
index 347fccb..67ea5a9 100644
--- a/lib/n65/symbol_table.rb
+++ b/lib/n65/symbol_table.rb
@@ -18,6 +18,19 @@ module N65
       }
       @anonymous_scope_number = 0
       @scope_stack = [:global]
+      @subroutine_cycles = {}
+    end
+
+
+    ####
+    ##  Add a running cycle count to current top level scopes (ie subroutines)
+    def add_cycles(cycles)
+      cycles ||= 0
+      top_level_subroutine = @scope_stack[1]
+      unless top_level_subroutine.nil?
+        @subroutine_cycles[top_level_subroutine] ||= 0
+        @subroutine_cycles[top_level_subroutine] += cycles
+      end
     end
 
 
@@ -29,7 +42,6 @@ module N65
       name = name.to_sym
       scope = current_scope
       if scope.has_key?(name)
-        #path_string = generate_scope_path(path_ary)
         fail(InvalidScope, "Scope: #{name} already exists")
       end
       scope[name] = {}
@@ -135,6 +147,13 @@ module N65
     end
 
 
+    ####
+    ##  Export a cycle count for top level subroutines
+    def export_cycle_count_yaml
+      @subroutine_cycles.to_yaml
+    end
+
+
     private
 
     ####
diff --git a/lib/n65/version.rb b/lib/n65/version.rb
index 0736b5e..7897e10 100644
--- a/lib/n65/version.rb
+++ b/lib/n65/version.rb
@@ -1,3 +1,3 @@
 module N65
-  VERSION ||= "1.5.2"
+  VERSION ||= "1.5.3"
 end