Ada Lovelace: The Woman Who Wrote the First Computer Program a Century Before Computers Existed

Ada Lovelace died in 1852. The first working electronic computer was not built until the 1940s, nearly a century later. And yet the document she produced in 1843, a set of notes attached to a translated article about a machine that was never built, is now recognized as the first computer program ever written.

The machine was Charles Babbage’s Analytical Engine. The translation was from a French article by an Italian engineer. The notes Ada added to that translation were three times longer than the article itself. In Note G, the last and most substantial, she wrote out a step-by-step algorithm for calculating Bernoulli numbers using the engine. That algorithm, a sequence of operations designed to produce a specific mathematical output, is what makes her the first programmer. She was 27 years old. She died nine years later from uterine cancer. Her notes sat largely unread for over a century before anyone understood what they were looking at.

Where She Came From

Ada was born Augusta Ada Byron on December 10, 1815, the only legitimate child of the poet Lord Byron and his wife Annabella Milbanke. Byron had called Annabella his “Princess of Parallelograms,” a half-mocking reference to her mathematical abilities. The marriage lasted barely a year. Byron left when Ada was a month old and died when she was eight, in the Greek War of Independence, having never seen his daughter again.

Annabella was determined that Ada would not inherit her father’s romantic instability. She arranged a rigorous scientific and mathematical education, unusual for a girl of any class in the 1820s. Ada was tutored in mathematics, music, and languages. She was also, by every account, intensely curious: at twelve she attempted to design a flying machine, studying bird anatomy and experimenting with materials before concluding that steam power might provide the necessary lift. The project failed. However, the curiosity that drove it did not.

In June 1833, at seventeen, Ada attended one of Charles Babbage’s Saturday evening soirées with her mother and their mutual friend, the mathematician Mary Somerville. Babbage showed her a small working section of his Difference Engine, a mechanical calculator he had been building with government funding. Most visitors were impressed by the machine as a curiosity. However, Ada understood what it could do. She and Babbage began a correspondence that lasted the rest of her life.

The Machine That Was Never Built

Babbage had moved on from the Difference Engine to something more ambitious: the Analytical Engine, a general-purpose programmable mechanical computer that could, in theory, perform any calculation. Where the Difference Engine was designed to produce mathematical tables, the Analytical Engine could be programmed, using punched cards borrowed from the Jacquard loom. It could follow any sequence of operations.

The machine was never completed. It exists only in Babbage’s designs and in the notes of the people who studied those designs. But the Analytical Engine, as designed, was a Turing-complete general-purpose computer. It had a mill, equivalent to a processor, and a store, equivalent to memory. Additionally, it could perform conditional branching: if a result met a certain condition, the program would take one path; if not, another. This is the fundamental logic of every computer program ever written.

Babbage gave a lecture on the Analytical Engine at the University of Turin in 1840. An Italian engineer named Luigi Menabrea transcribed it in French, and the transcript was published in 1842. Babbage asked Ada to translate it into English. She did. She also added her own commentary, the notes that would make her famous, and she signed them with her initials: A.A.L.

What the Notes Actually Said

The notes were not marginal additions. They were the more important document. Ada used them to explain concepts that Babbage had not clearly articulated. She also used them to extend the scope of what the machine could do in ways he had not considered.

Her most remarkable observation was that the Analytical Engine was not merely a calculator. It could manipulate any symbols according to rules, not just numbers. She speculated that it could compose music, if musical notes could be expressed and their relationships encoded. She envisioned a machine that could work with letters, with logical propositions, with anything that could be given a symbolic form.

This was not Babbage’s idea. Babbage thought of his machine as a very powerful calculator. Yet Ada saw something more general: a machine for processing symbols according to rules, which is what computers actually are. Her insight predated by a century the theoretical work of Alan Turing. He formalized the same concept in 1936, and his work formed the intellectual foundation of modern computing.

In Note G, the final and most technical of the seven notes, she wrote out the algorithm for the Bernoulli numbers. This was the example that demonstrated, concretely, how the engine would execute a complex calculation through a sequence of steps. It included what modern programmers call a loop: a set of operations repeated multiple times with different values. Additionally, the algorithm was sufficiently detailed that it could, in principle, have been run on the machine had the machine existed.