diff --git a/2019/day7.py b/2019/day7.py
index bc05a08..83a8e2c 100644
--- a/2019/day7.py
+++ b/2019/day7.py
@@ -1,4 +1,6 @@
 import itertools
+from queue import Queue
+from threading import Thread
 
 from intcode import Intcode
 
@@ -8,15 +10,58 @@ def main():
         first_line = input_file.readlines()[0]
     codes = Intcode.parse_input(first_line)
 
+    # Part 1
     phase_settings_perm = itertools.permutations(range(5), 5)
     max_output = 0
     for phases in phase_settings_perm:
         inout = 0
         for amp_id in range(5):
-            inout = Intcode(codes).run([phases[amp_id], inout])
+            amp = Amp(codes)
+            amp.run([phases[amp_id], inout])
+            inout = amp.output_queue.get()
         max_output = max(max_output, inout)
     print("Max output:", max_output)
 
+    # Part 2
+    phase_settings_perm = itertools.permutations(range(5, 10), 5)
+    max_output = 0
+    for phases in phase_settings_perm:
+        inout = 0
+        amps = [Amp(codes) for _ in range(5)]
+        threads = []
+        for amp_id, amp in enumerate(amps):
+            parent_index = (amp_id - 1) % 5
+            amp.parent = amps[parent_index]
+            args = [[phases[amp_id]]]
+            if amp_id == 0:
+                args[0].append(0)
+            threads.append(Thread(target=amp.run, args=args))
+
+        for thread in threads:
+            thread.start()
+        for thread in threads:
+            thread.join()
+
+        inout = amp.output_queue.get()
+        max_output = max(max_output, inout)
+    print("Max output chained:", max_output)
+
+
+class Amp(Intcode):
+
+    def __init__(self, codes):
+        super().__init__(codes)
+        self.parent = None
+        self.output_queue = Queue()
+
+    def input_data(self):
+        if self.inputs:
+            return self.inputs.pop(0)
+        return self.parent.output_queue.get()
+
+    def output_data(self, data):
+        self.output_queue.put(data)
+
 
 if __name__ == "__main__":
     main()