diff --git a/2019/d05/ex1/ex1.py b/2019/d05/ex1/ex1.py
new file mode 100755
index 0000000..09dac02
--- /dev/null
+++ b/2019/d05/ex1/ex1.py
@@ -0,0 +1,103 @@
+#!/usr/bin/env python
+
+import sys
+from copy import deepcopy
+from enum import IntEnum
+from typing import List, NamedTuple
+
+
+class ParameterMode(IntEnum):
+    POSITION = 0  # Acts on address
+    IMMEDIATE = 1  # Acts on the immediate value
+
+
+class Instruction(NamedTuple):
+    address: int  # The address of the instruction, for convenience
+    op: int  # The opcode
+    p1_mode: ParameterMode  # Which mode is the first parameter in
+    p2_mode: ParameterMode  # Which mode is the second parameter in
+    p3_mode: ParameterMode  # Which mode is the third parameter in
+
+
+def lookup_ops(index: int, memory: List[int]) -> Instruction:
+    digits = list(map(int, str(memory[index])))
+    a, b, c, d, e = [0] * (5 - len(digits)) + digits  # Pad with default values
+    return Instruction(
+        address=index,
+        op=d * 10 + e,
+        p1_mode=ParameterMode(c),
+        p2_mode=ParameterMode(b),
+        p3_mode=ParameterMode(a),
+    )
+
+
+def do_addition(instr: Instruction, memory: List[int]) -> int:
+    lhs, rhs, dest = memory[instr.address + 1 : instr.address + 4]
+    if instr.p1_mode == ParameterMode.POSITION:
+        lhs = memory[lhs]
+    if instr.p2_mode == ParameterMode.POSITION:
+        rhs = memory[rhs]
+    assert instr.p3_mode != ParameterMode.IMMEDIATE  # Sanity check
+    memory[dest] = lhs + rhs
+
+    return 4  # Length of the instruction
+
+
+def do_multiplication(instr: Instruction, memory: List[int]) -> int:
+    lhs, rhs, dest = memory[instr.address + 1 : instr.address + 4]
+    if instr.p1_mode == ParameterMode.POSITION:
+        lhs = memory[lhs]
+    if instr.p2_mode == ParameterMode.POSITION:
+        rhs = memory[rhs]
+    assert instr.p3_mode != ParameterMode.IMMEDIATE  # Sanity check
+    memory[dest] = lhs * rhs
+
+    return 4  # Length of the instruction
+
+
+def do_input(instr: Instruction, memory: List[int]) -> int:
+    value = int(input())
+    param = memory[instr.address + 1]
+
+    assert instr.p1_mode == ParameterMode.POSITION  # Sanity check
+    memory[param] = value
+
+    return 2  # Length of the instruction
+
+
+def do_output(instr: Instruction, memory: List[int]) -> int:
+    value = memory[instr.address + 1]
+    if instr.p1_mode == ParameterMode.POSITION:
+        value = memory[value]
+    else:
+        assert instr.p1_mode == ParameterMode.IMMEDIATE  # Sanity check
+
+    print(value)
+
+    return 2  # Length of the instruction
+
+
+def run_op(memory: List[int]) -> None:
+    index = 0
+    while True:
+        instr = lookup_ops(index, memory)
+        if instr.op == 99:  # Halt
+            return
+        elif instr.op == 1:  # Sum
+            index += do_addition(instr, memory)
+        elif instr.op == 2:  # Multiplication
+            index += do_multiplication(instr, memory)
+        elif instr.op == 3:  # Load from input
+            index += do_input(instr, memory)
+        elif instr.op == 4:  # Store to output
+            index += do_output(instr, memory)
+
+
+def main() -> None:
+    with open("input") as mem_f:
+        memory = [int(n) for n in mem_f.read().split(",")]
+        run_op(memory)
+
+
+if __name__ == "__main__":
+    main()