diff --git a/README.org b/README.org
index 4bfbace..4afbf22 100644
--- a/README.org
+++ b/README.org
@@ -8,3 +8,4 @@ It as of right now has no particular ambitions, but rather an exploration of emu
 Information about the system was found from the following:
 - [[https://gekkio.fi/files/gb-docs/gbctr.pdf][Game Boy: Complete Technical reference]]
 - [[https://rylev.github.io/DMG-01/public/book/introduction.html][DMG-01: How to Emulate a Game Boy]]
+- [[https://rgbds.gbdev.io/][RGBDS]]
diff --git a/src/GBC/CPU.hs b/src/GBC/CPU.hs
index 494ad30..5c87366 100644
--- a/src/GBC/CPU.hs
+++ b/src/GBC/CPU.hs
@@ -75,6 +75,8 @@ rhl = lens (\r -> ((.<<. 8) . fromIntegral $ r ^. rh) + (fromIntegral $ r ^. rl)
           (\r w -> r & rh %~ (const $ fromIntegral $ w .>>. 8) & rl %~ (const $ fromIntegral $ w .&. 255))
 
 data CPU = CPU { _registers :: Registers
+               , _ir :: Word8
+               , _ie :: Word8
                , _pc :: Word16
                , _sp :: Word16
                , _bus :: (V.Vector 65536 Word8) }
@@ -190,6 +192,18 @@ data Instruction where
   JRE :: { rel :: Int8 } -> Instruction
   JRCCE :: { rel :: Int8, flag :: FlagTarget, op'' :: Bool -> Bool } -> Instruction
 
+  CALLNN :: { val' :: Word16 } -> Instruction
+  CALLCCNN :: { val' :: Word16, flag :: FlagTarget, op'' :: Bool -> Bool } -> Instruction
+  RET :: Instruction
+  RETCC :: { flag :: FlagTarget, op'' :: Bool -> Bool } -> Instruction
+  RETI :: Instruction
+  RSTN :: { val' :: Word16 } -> Instruction
+  HALT :: Instruction
+  STOP :: Instruction
+  DI :: Instruction
+  EI :: Instruction
+  NOP :: Instruction
+
 execute :: CPU -> Instruction -> CPU
 execute cpu = \case
   ADDR t _c -> let value = cpu ^. t
@@ -434,6 +448,17 @@ execute cpu = \case
                      cpu & pc .~ target
                    else
                      cpu
+  CALLNN v -> undefined
+  CALLCCNN v _f op -> undefined
+  RET -> undefined
+  RETCC _f op -> undefined
+  RETI -> undefined
+  RSTN v -> undefined
+  HALT -> undefined
+  STOP -> undefined
+  DI -> undefined
+  EI -> undefined
+  NOP -> cpu
   where
     add :: Word8 -> Word8 -> Bool -> (Word8, FlagRegister)
     add o n _c = let new        = o + n + if _c then 1 else 0