diff --git a/bin/assembler b/bin/assembler
index 6dac0a7..6e1c53f 100755
--- a/bin/assembler
+++ b/bin/assembler
@@ -32,6 +32,9 @@ PREDEFINED_SYMBOLS = {
   'KBD'    => 0x6000
 }
 
+# Any more than this and then we overflow 15bits of address space
+MAX_PROGRAM_SIZE = (2**15) -1
+
 def add_predefined_symbols(symbols)
   PREDEFINED_SYMBOLS.each do |k, v|
     symbols.add_entry(k, v)
@@ -52,6 +55,8 @@ def parse_labels(input, symbols)
       address += 1
     end
   end
+
+  raise "Program is too large: #{address} > #{MAX_PROGRAM_SIZE}" if address >= MAX_PROGRAM_SIZE
 end
 
 def generate_code(input, symbols)
diff --git a/lib/code.rb b/lib/code.rb
index e3db601..0c61e3a 100644
--- a/lib/code.rb
+++ b/lib/code.rb
@@ -29,21 +29,27 @@ def comp(mnemonic)
       'A+1' => '0110111',
       'D-1' => '0001110',
       'A-1' => '0110010',
+      'A+D' => '0000010',
       'D+A' => '0000010',
       'D-A' => '0010011',
       'A-D' => '0000111',
       'D&A' => '0000000',
+      'A&D' => '0000000',
       'D|A' => '0010101',
+      'A|D' => '0010101',
       'M'   => '1110000',
       '!M'  => '1110001',
       '-M'  => '1110011',
       'M+1' => '1110111',
       'M-1' => '1110010',
       'D+M' => '1000010',
+      'M+D' => '1000010',
       'D-M' => '1010011',
       'M-D' => '1000111',
       'D&M' => '1000000',
-      'D|M' => '1010101'
+      'D|M' => '1010101',
+      'M&D' => '1000000',
+      'M|D' => '1010101',
     }.fetch(mnemonic)
   end