diff --git a/app/ed.py b/app/ed.py
new file mode 100644
index 0000000..c3a5072
--- /dev/null
+++ b/app/ed.py
@@ -0,0 +1,167 @@
+# A simple line-oriented text editor for MicroPython/CircuitPython
+# implementing the POSIX 'ed' subset
+# Usage: from app.ed import edit
+# Created by Luxferre in 2025, released into public domain
+
+from deck.input import input
+
+class Ed:
+  def __init__(self, filename=None):
+    self.filename = filename
+    self.buffer = []
+    self.current_line = 0  # 1-indexed for the user, 0 means empty or before first line
+    self.dirty = False
+    self.last_error = ""
+
+    if filename:
+      try:
+        with open(filename, "r") as f:
+          self.buffer = [line.rstrip("\n\r") for line in f.readlines()]
+        self.current_line = len(self.buffer)
+        print(len("".join(self.buffer)) + len(self.buffer)) # Print byte count
+      except OSError:
+        print(f"cannot open input file {filename}")
+
+  def _parse_address(self, addr_str):
+    """Simple address parser for line numbers, '.', and '$'."""
+    if not addr_str:
+      return self.current_line
+    if addr_str == ".":
+      return self.current_line
+    if addr_str == "$":
+      return len(self.buffer)
+    try:
+      return int(addr_str)
+    except ValueError:
+      return None
+
+  def _get_range(self, addr_range):
+    """Parses ranges like '1,5' or '%'."""
+    if not addr_range:
+      return self.current_line, self.current_line
+    if addr_range == ",":
+      return 1, len(self.buffer)
+    if addr_range == "%":
+      return 1, len(self.buffer)
+    
+    parts = addr_range.split(",")
+    if len(parts) == 1:
+      addr = self._parse_address(parts[0])
+      return addr, addr
+    else:
+      return self._parse_address(parts[0]), self._parse_address(parts[1])
+
+  def run(self):
+    while True:
+      try:
+        cmd_line = input(": ").strip()
+      except EOFError:
+        break
+
+      if not cmd_line:
+        # A null command (just newline) prints the current line
+        if self.buffer:
+          print(self.buffer[self.current_line - 1])
+        continue
+
+      # Basic command regex-like split
+      # Format: [address]command[parameters]
+      cmd_char = ""
+      addr_part = ""
+      for i, char in enumerate(cmd_line):
+        if char.isalpha():
+          addr_part = cmd_line[:i]
+          cmd_char = char
+          params = cmd_line[i+1:].strip()
+          break
+      else:
+        # If no alpha command found, try interpreting as address only
+        addr = self._parse_address(cmd_line)
+        if addr is not None and 0 <= addr <= len(self.buffer):
+          self.current_line = addr
+          if self.current_line > 0:
+            print(self.buffer[self.current_line - 1])
+          continue
+        else:
+          print("?")
+          continue
+
+      try:
+        start, end = self._get_range(addr_part)
+        
+        if cmd_char == 'q':
+          if self.dirty and params != "!":
+            print("?")
+            self.dirty = False # Standard ed behavior: second q forces exit
+            continue
+          break
+
+        elif cmd_char == 'p' or cmd_char == 'n':
+          if not self.buffer:
+            print("?")
+            continue
+          start = max(1, start)
+          end = min(len(self.buffer), end)
+          for i in range(start - 1, end):
+            if cmd_char == 'n':
+              print(f"{i + 1}\t{self.buffer[i]}")
+            else:
+              print(self.buffer[i])
+          self.current_line = end
+
+        elif cmd_char == 'a':
+          idx = start
+          while True:
+            line = input("")
+            if line == ".":
+              break
+            self.buffer.insert(idx, line)
+            idx += 1
+            self.dirty = True
+          self.current_line = idx
+
+        elif cmd_char == 'i':
+          idx = max(0, start - 1)
+          while True:
+            line = input("")
+            if line == ".":
+              break
+            self.buffer.insert(idx, line)
+            idx += 1
+            self.dirty = True
+          self.current_line = idx
+
+        elif cmd_char == 'd':
+          if not self.buffer:
+            print("?")
+            continue
+          del self.buffer[start-1 : end]
+          self.current_line = min(start, len(self.buffer))
+          self.dirty = True
+
+        elif cmd_char == 'w':
+          target = params if params else self.filename
+          if not target:
+            print("?")
+            continue
+          with open(target, "w") as f:
+            for line in self.buffer:
+              f.write(line + "\n")
+          print(len("".join(self.buffer)) + len(self.buffer))
+          self.dirty = False
+          self.filename = target
+
+        elif cmd_char == 'f':
+          if params:
+            self.filename = params
+          print(self.filename if self.filename else "No current filename")
+
+        else:
+          print("?")
+
+      except Exception:
+        print("?")
+
+def edit(fname):
+  editor = Ed(fname)
+  editor.run()