diff --git a/assembler/.rubocop.yml b/assembler/.rubocop.yml
new file mode 100644
index 0000000..cc32da4
--- /dev/null
+++ b/assembler/.rubocop.yml
@@ -0,0 +1 @@
+inherit_from: .rubocop_todo.yml
diff --git a/assembler/.rubocop_todo.yml b/assembler/.rubocop_todo.yml
new file mode 100644
index 0000000..6581c4f
--- /dev/null
+++ b/assembler/.rubocop_todo.yml
@@ -0,0 +1,9 @@
+# This configuration was generated by
+# `rubocop --auto-gen-config`
+# on 2020-05-29 19:24:00 +0530 using RuboCop version 0.79.0.
+# The point is for the user to remove these configuration records
+# one by one as the offenses are removed from the code base.
+# Note that changes in the inspected code, or installation of new
+# versions of RuboCop, may require this file to be generated again.
+AllCops:
+  TargetRubyVersion: 2.7
diff --git a/assembler/assembler.rb b/assembler/assembler.rb
new file mode 100644
index 0000000..1efc2d4
--- /dev/null
+++ b/assembler/assembler.rb
@@ -0,0 +1,118 @@
+# frozen_string_literal: true
+
+fn = ARGV[0]
+ic = 0
+
+class Code
+  DEST_MAP = {
+    'null' => [0, 0, 0],
+    'M' => [0, 0, 1],
+    'D' => [0, 1, 0],
+    'MD' => [0, 1, 1],
+    'A' => [1, 0, 0],
+    'AM' => [1, 0, 1],
+    'AD' => [1, 1, 0],
+    'AMD' => [1, 1, 1]
+  }.freeze
+
+  JUMP_MAP = {
+    'null' => [0, 0, 0],
+    'JGT' => [0, 0, 1],
+    'JEQ' => [0, 1, 0],
+    'JGE' => [0, 1, 1],
+    'JLT' => [1, 0, 0],
+    'JNE' => [1, 0, 1],
+    'JLE' => [1, 1, 0],
+    'JMP' => [1, 1, 1]
+  }.freeze
+  COMP_MAP = {
+    '0' => '101010',
+    '1' => '111111',
+    '-1' => '111010',
+    'D' => '001100',
+    'Y' => '110000',
+    '!D' => '001101',
+    '!Y' => '110001',
+    '-D' => '001111',
+    '-Y' => '110011',
+    'D+1' => '011111',
+    'Y+1' => '110111',
+    'D-1' => '001110',
+    'Y-1' => '110010',
+    'D+Y' => '000010',
+    'D-Y' => '010011',
+    'Y-D' => '000111',
+    'D&Y' => '000000',
+    'D|Y' => '010101'
+  }.freeze
+  def self.dest(str)
+    Code::DEST_MAP[str]
+  end
+
+  def self.jump(str)
+    Code::JUMP_MAP[str]
+  end
+
+  def self.comp(str)
+    a = c1 = c2 = c3 = c4 = c5 = c6 = 0
+    a = str.include? 'M'
+    key = str.gsub(/[AM]/, 'Y')
+    (a ? '1' : '0') + COMP_MAP[key]
+  end
+end
+
+class Parser
+  def more_commands?
+    @ic < @lines.size
+  end
+
+  def advance
+    @ic += 1
+  end
+
+  def line
+    @lines[@ic]
+  end
+
+  def command_type
+    case line[0]
+    when '@'
+      :A_COMMAND
+    when '('
+      :L_COMMAND
+    else
+      :C_COMMAND
+    end
+  end
+
+  def symbol
+    case command_type
+    when :A_COMMAND
+      line[1..-1]
+    when :L_COMMAND
+      line[1..-2]
+    end
+  end
+
+  def dest; end
+
+  def comp; end
+
+  def jump; end
+
+  def run
+    advance while more_commands?
+  end
+
+  def initialize(_file_name)
+    @ic = 0
+    @lines = []
+    File.readlines(fn).each do |line|
+      line.chomp!
+      next if line.empty?
+      next if line[0...2] == '//'
+
+      @lines << line
+    end
+  end
+end