diff --git a/hs-term-emulator.cabal b/hs-term-emulator.cabal
--- a/hs-term-emulator.cabal
+++ b/hs-term-emulator.cabal
@@ -1,6 +1,6 @@
 cabal-version:      2.4
 name:               hs-term-emulator
-version:            0.1.0.3
+version:            0.1.0.4
 synopsis:           Terminal Emulator written in 100% Haskell
 description:        See: https://github.com/bitc/hs-term-emulator#readme
 homepage:           https://github.com/bitc/hs-term-emulator
@@ -29,7 +29,6 @@
     System.Terminal.Emulator.Term
     System.Terminal.Emulator.Term.Process
     System.Terminal.Emulator.Term.Resize
-    System.Terminal.Emulator.Term.TermChange
     System.Terminal.Emulator.TermLines
 
   build-depends:
@@ -51,7 +50,11 @@
   main-is:            Spec.hs
 
   -- cabal-fmt: expand test -Spec
-  other-modules:      System.Terminal.Emulator.Parsing.InternalSpec
+  other-modules:
+    System.Terminal.Emulator.Parsing.InternalSpec
+    System.Terminal.Emulator.Term.ProcessSpec
+    System.Terminal.Emulator.Term.SimpleTerm
+
   hs-source-dirs:     test
   build-depends:
     , ansi-terminal     ^>=0.11
@@ -59,6 +62,7 @@
     , base              >=4.10     && <5
     , hs-term-emulator
     , hspec             ^>=2.8.2
+    , lens              ^>=5.0.1
     , text
     , vector            ^>=0.12.3.0
 
diff --git a/src/System/Terminal/Emulator/DECPrivateMode.hs b/src/System/Terminal/Emulator/DECPrivateMode.hs
--- a/src/System/Terminal/Emulator/DECPrivateMode.hs
+++ b/src/System/Terminal/Emulator/DECPrivateMode.hs
@@ -137,7 +137,7 @@
     --
     -- @DECRST@: Reset bracketed paste mode.
     BracketedPasteMode
-  deriving (Eq, Show)
+  deriving (Show, Eq, Ord, Enum, Bounded)
 
 intToDECPrivateMode :: Int -> Maybe DECPrivateMode
 intToDECPrivateMode 1 = Just DECCKM
diff --git a/src/System/Terminal/Emulator/Parsing/Types.hs b/src/System/Terminal/Emulator/Parsing/Types.hs
--- a/src/System/Terminal/Emulator/Parsing/Types.hs
+++ b/src/System/Terminal/Emulator/Parsing/Types.hs
@@ -12,7 +12,7 @@
   | TermAtom_SingleCharacterFunctionUnknown !Char
   | TermAtom_EscapeSequence !EscapeSequence
   | TermAtom_EscapeSequenceUnknown !Text
-  deriving (Eq, Show)
+  deriving (Show, Eq)
 
 data SingleCharacterFunction
   = -- | @BEL@ Bell (BEL  is Ctrl-G).
@@ -35,7 +35,7 @@
     Control_Tab
   | -- | @VT@ Vertical Tab (VT  is Ctrl-K).  This is treated the same as LF.
     Control_VerticalTab
-  deriving (Eq, Show)
+  deriving (Show, Eq, Ord, Enum, Bounded)
 
 data EscapeSequence
   = -- | @ESC M@ Reverse Index (RI  is 0x8d).
@@ -50,7 +50,7 @@
     ESC_SetG0CharacterSet !Text
   | Esc_CSI !ControlSequenceIntroducer
   | Esc_OSC !OperatingSystemCommand
-  deriving (Eq, Show)
+  deriving (Show, Eq)
 
 data ControlSequenceIntroducer
   = -- | @CSI Ps `@  Character Position Absolute  [column] (default = [row,1]) (HPA).
@@ -120,7 +120,7 @@
   | -- | Unknown DECRST (DEC Private Mode Reset) code
     CSI_DECRST_Unknown !Int
   | CSI_SGR !(Vector SGR)
-  deriving (Eq, Show)
+  deriving (Show, Eq)
 
 data EraseInLineParam
   = -- | @Ps = 0@ Erase to Right (default).
@@ -129,7 +129,7 @@
     ClearFromCursorToBeginningOfLine
   | -- | @Ps = 2@  Erase All.
     ClearEntireLine
-  deriving (Eq, Show)
+  deriving (Show, Eq, Ord, Enum, Bounded)
 
 data EraseInDisplayParam
   = -- | @Ps = 0@ Erase Below (default).
@@ -140,21 +140,21 @@
     EraseAll
   | -- | @Ps = 3@ Erase Saved Lines, xterm.
     EraseSavedLines
-  deriving (Eq, Show)
+  deriving (Show, Eq, Ord, Enum, Bounded)
 
 data WindowManipulation
   = -- | @22;0@ Save xterm icon and window title on stack.
     SaveIconAndWindowTitleOnStack
   | -- | @23;0@ Restore xterm icon and window title from stack.
     RestoreIconAndWindowTitleOnStack
-  deriving (Eq, Show)
+  deriving (Show, Eq, Ord, Enum, Bounded)
 
 data DeviceStatusReport
   = -- | Status Report. Result ("OK") is @CSI 0 n@
     StatusReport
   | -- | Report Cursor Position (CPR) [row;column]. Result is @CSI r ; c R@
     ReportCursorPosition
-  deriving (Eq, Show)
+  deriving (Show, Eq, Ord, Enum, Bounded)
 
 data Mode
   = -- | Keyboard Action Mode (KAM)
@@ -165,11 +165,11 @@
     SendReceive
   | -- | Automatic Newline / Normal Linefeed (LNM).
     AutomaticNewlineNormalLinefeed
-  deriving (Eq, Show)
+  deriving (Show, Eq, Ord, Enum, Bounded)
 
 data SendDeviceAttributesSecondary
   = RequestTerminalIdentificationCode
-  deriving (Eq, Show)
+  deriving (Show, Eq, Ord, Enum, Bounded)
 
 data OperatingSystemCommand
   = -- | Change Icon Name and Window Title
@@ -190,7 +190,7 @@
     OSC_RequestTextBackgroundColor
   | -- | @Ps = 112@ Reset text cursor color.
     OSC_ResetTextCursorColor
-  deriving (Eq, Show)
+  deriving (Show, Eq, Ord)
 
 codeToSGR :: Int -> Maybe SGR.SGR
 codeToSGR 0 = Just SGR.Reset
diff --git a/src/System/Terminal/Emulator/Term/Process.hs b/src/System/Terminal/Emulator/Term/Process.hs
--- a/src/System/Terminal/Emulator/Term/Process.hs
+++ b/src/System/Terminal/Emulator/Term/Process.hs
@@ -90,7 +90,7 @@
 processEscapeSequence (Esc_CSI (CSI_DeleteLines n)) = nw $ deleteLines n
 processEscapeSequence (Esc_CSI (CSI_CursorCharacterAbsolute col)) = nw $ \term -> cursorMoveTo (term ^. cursorPos . _1, col - 1) term
 processEscapeSequence (Esc_CSI (CSI_CharacterPositionAbsolute col)) = nw $ \term -> cursorMoveTo (term ^. cursorPos . _1, col - 1) term
-processEscapeSequence (Esc_CSI (CSI_CursorPosition row col)) = nw $ cursorMoveAbsoluteTo (row - 1, col -1)
+processEscapeSequence (Esc_CSI (CSI_CursorPosition row col)) = nw $ cursorMoveAbsoluteTo (row - 1, col - 1)
 processEscapeSequence (Esc_CSI (CSI_HorizontalVerticalPosition row col)) = nw $ cursorMoveAbsoluteTo (row - 1, col - 1)
 processEscapeSequence (Esc_CSI (CSI_LinePositionAbsolute row)) = nw $ \term -> cursorMoveAbsoluteTo (row - 1, term ^. cursorPos . _2) term
 processEscapeSequence (Esc_CSI (CSI_ScrollUp n)) = nw $ \term -> scrollUp (term ^. scrollTop) n term
diff --git a/src/System/Terminal/Emulator/Term/TermChange.hs b/src/System/Terminal/Emulator/Term/TermChange.hs
deleted file mode 100644
--- a/src/System/Terminal/Emulator/Term/TermChange.hs
+++ /dev/null
@@ -1,5 +0,0 @@
-module System.Terminal.Emulator.Term.TermChange where
-
-data TermChange
-  = MoveCursor !Int !Int
-  | X
diff --git a/src/System/Terminal/Emulator/TermLines.hs b/src/System/Terminal/Emulator/TermLines.hs
--- a/src/System/Terminal/Emulator/TermLines.hs
+++ b/src/System/Terminal/Emulator/TermLines.hs
@@ -6,6 +6,7 @@
     TermLines,
     empty,
     length,
+    singleton,
     replicate,
     vIndex,
     head,
@@ -15,6 +16,7 @@
     drop,
     dropLast,
     traverseWithIndex,
+    toSeq,
   )
 where
 
@@ -31,7 +33,7 @@
 type TermLines = StrictSeq TermLine
 
 newtype StrictSeq a = StrictSeq (Seq a)
-  deriving (Show, Eq, Ord, Functor, Semigroup)
+  deriving (Show, Eq, Ord, Functor, Semigroup, Monoid, Foldable)
 
 -- | The empty sequence.
 empty :: StrictSeq a
@@ -43,9 +45,13 @@
 length (StrictSeq v) = Seq.length v
 {-# INLINE length #-}
 
+singleton :: a -> StrictSeq a
+singleton x = x `seq` (StrictSeq (Seq.singleton x))
+{-# INLINE singleton #-}
+
 -- | @replicate n x@ is a sequence consisting of n copies of x.
 replicate :: Int -> a -> StrictSeq a
-replicate n x = StrictSeq $ Seq.replicate n x
+replicate n x = x `seq` (StrictSeq (Seq.replicate n x))
 {-# INLINE replicate #-}
 
 -- | A lens to the specified index of the sequence. Must be in range.
@@ -104,3 +110,7 @@
 traverseWithIndex :: Applicative f => (Int -> a -> f b) -> StrictSeq a -> f (StrictSeq b)
 traverseWithIndex f (StrictSeq v) = StrictSeq <$> (Seq.traverseWithIndex f v)
 {-# INLINE traverseWithIndex #-}
+
+toSeq :: StrictSeq a -> Seq a
+toSeq (StrictSeq v) = v
+{-# INLINE toSeq #-}
diff --git a/test/System/Terminal/Emulator/Term/ProcessSpec.hs b/test/System/Terminal/Emulator/Term/ProcessSpec.hs
new file mode 100644
--- /dev/null
+++ b/test/System/Terminal/Emulator/Term/ProcessSpec.hs
@@ -0,0 +1,185 @@
+{-# LANGUAGE OverloadedStrings #-}
+
+module System.Terminal.Emulator.Term.ProcessSpec where
+
+import Control.Applicative (many)
+import Data.Attoparsec.Text
+import Data.Text (Text)
+import System.Terminal.Emulator.Parsing (parseTermAtom)
+import System.Terminal.Emulator.Term (Term, mkTerm)
+import System.Terminal.Emulator.Term.Process (processTermAtoms)
+import System.Terminal.Emulator.Term.SimpleTerm (SimpleTerm (..), termToSimpleTerm)
+import Test.Hspec
+
+blankTerm :: Term
+blankTerm = mkTerm (10, 4)
+
+runTerminal :: Term -> Text -> Term
+runTerminal term input =
+  case parseOnly (many parseTermAtom <* endOfInput) input of
+    Left err -> error $ "Error parsing terminal input: " <> err
+    Right ts ->
+      let (_, term') = processTermAtoms ts term
+       in term'
+
+testCase :: (Term, Text) -> SimpleTerm -> Expectation
+testCase (initialTerm, input) expected =
+  let term' = runTerminal initialTerm input
+      actual = termToSimpleTerm term'
+   in actual `shouldBe` expected
+
+spec :: Spec
+spec = do
+  describe "ProcessSpec" $ do
+    it "No Input" $
+      testCase
+        (blankTerm, "")
+        SimpleTerm
+          { st_ScrollBackLines = [],
+            st_Screen =
+              [ "          ",
+                "          ",
+                "          ",
+                "          "
+              ],
+            st_CursorPos = (0, 0)
+          }
+
+    it "Single char" $
+      testCase
+        (blankTerm, "A")
+        SimpleTerm
+          { st_ScrollBackLines = [],
+            st_Screen =
+              [ "A         ",
+                "          ",
+                "          ",
+                "          "
+              ],
+            st_CursorPos = (0, 1)
+          }
+
+    it "Multiple chars" $
+      testCase
+        (blankTerm, "AB")
+        SimpleTerm
+          { st_ScrollBackLines = [],
+            st_Screen =
+              [ "AB        ",
+                "          ",
+                "          ",
+                "          "
+              ],
+            st_CursorPos = (0, 2)
+          }
+
+    it "Newlines" $
+      testCase
+        (blankTerm, "A\n\n\n")
+        SimpleTerm
+          { st_ScrollBackLines = [],
+            st_Screen =
+              [ "A         ",
+                "          ",
+                "          ",
+                "          "
+              ],
+            st_CursorPos = (3, 1)
+          }
+
+    it "Scroll up" $
+      testCase
+        (blankTerm, "A\n\n\n\n")
+        SimpleTerm
+          { st_ScrollBackLines =
+              [ "A         "
+              ],
+            st_Screen =
+              [ "          ",
+                "          ",
+                "          ",
+                "          "
+              ],
+            st_CursorPos = (3, 1)
+          }
+
+    it "Scroll up 2" $
+      testCase
+        (blankTerm, "A\nB\n\n\n\n")
+        SimpleTerm
+          { st_ScrollBackLines =
+              [ "A         ",
+                " B        "
+              ],
+            st_Screen =
+              [ "          ",
+                "          ",
+                "          ",
+                "          "
+              ],
+            st_CursorPos = (3, 2)
+          }
+
+    it "Cursor Down 1" $
+      testCase
+        (blankTerm, "A\ESC[B")
+        SimpleTerm
+          { st_ScrollBackLines = [],
+            st_Screen =
+              [ "A         ",
+                "          ",
+                "          ",
+                "          "
+              ],
+            st_CursorPos = (1, 1)
+          }
+
+    it "Cursor Down past bottom" $
+      testCase
+        (blankTerm, "A\ESC[B\ESC[B\ESC[B\ESC[B")
+        SimpleTerm
+          { st_ScrollBackLines = [],
+            st_Screen =
+              [ "A         ",
+                "          ",
+                "          ",
+                "          "
+              ],
+            st_CursorPos = (3, 1)
+          }
+
+    -- TODO modern terminals don't add to the scrollback
+    it "Scroll up 2" $
+      testCase
+        (blankTerm, "A\ESC[2S")
+        SimpleTerm
+          { st_ScrollBackLines =
+              [ "A         ",
+                "          "
+              ],
+            st_Screen =
+              [ "          ",
+                "          ",
+                "          ",
+                "          "
+              ],
+            st_CursorPos = (0, 1)
+          }
+
+    -- TODO modern terminals don't add to the scrollback
+    it "Delete lines 2" $
+      testCase
+        (blankTerm, "A\ESC[2M")
+        SimpleTerm
+          { st_ScrollBackLines =
+              [ "A         ",
+                "          "
+              ],
+            st_Screen =
+              [ "          ",
+                "          ",
+                "          ",
+                "          "
+              ],
+            st_CursorPos = (0, 1)
+          }
diff --git a/test/System/Terminal/Emulator/Term/SimpleTerm.hs b/test/System/Terminal/Emulator/Term/SimpleTerm.hs
new file mode 100644
--- /dev/null
+++ b/test/System/Terminal/Emulator/Term/SimpleTerm.hs
@@ -0,0 +1,30 @@
+module System.Terminal.Emulator.Term.SimpleTerm
+  ( SimpleTerm (..),
+    termToSimpleTerm,
+  )
+where
+
+import Control.Lens
+import Data.Foldable (toList)
+import qualified Data.Vector.Unboxed as VU
+import System.Terminal.Emulator.Term (Term, cursorPos, scrollBackLines, termScreen)
+import System.Terminal.Emulator.TermLines (TermLine)
+
+-- | A simplified terminal that doesn't have an alt screen or colors
+data SimpleTerm = SimpleTerm
+  { st_ScrollBackLines :: [[Char]],
+    st_Screen :: [[Char]],
+    st_CursorPos :: (Int, Int)
+  }
+  deriving (Show, Eq, Ord)
+
+termToSimpleTerm :: Term -> SimpleTerm
+termToSimpleTerm term =
+  SimpleTerm
+    { st_ScrollBackLines = map termLineToStLine $ toList $ term ^. scrollBackLines,
+      st_Screen = map termLineToStLine $ toList $ term ^. termScreen,
+      st_CursorPos = term ^. cursorPos
+    }
+
+termLineToStLine :: TermLine -> [Char]
+termLineToStLine = map fst . VU.toList