In 1843 she wrote software for a machine that didn't exist yet.
Ada Lovelace (1815–1852), daughter of Lord Byron, was the English mathematician who wrote the first computer program: her 1843 notes on Charles Babbage's Analytical Engine contain a step-by-step algorithm for computing Bernoulli numbers — published a full century before the first electronic computer.
Working from an Italian paper on Babbage's unbuilt machine, she added notes three times longer than the original, seeing what Babbage himself had missed: that a machine manipulating numbers could manipulate any symbols — and might one day compose music.
Augusta Ada King, Countess of Lovelace, was born in London in 1815, the only legitimate child of the poet Lord Byron, who left England forever when she was weeks old. Her mother, determined Ada would not inherit her father's 'poetic madness', steered her toward mathematics.
Tutored by the scientist Mary Somerville and the logician Augustus De Morgan, Ada met the inventor Charles Babbage in 1833 and became fascinated by his Difference Engine — and then by his far grander design, the Analytical Engine, a general-purpose mechanical computer that was never built.
In 1843 she translated a French-language paper by the Italian engineer Luigi Menabrea on the Analytical Engine, and appended seven notes of her own — labeled A through G — totaling some 20,000 words. Note G gives a complete method for the Engine to compute Bernoulli numbers: loops, working variables, step-by-step operations. It is recognized as the first published computer program.
More visionary still was her leap beyond arithmetic: the Engine, she wrote, 'might act upon other things besides number' — symbols, harmonies, any relations that could be expressed formally. She called her approach 'poetical science'.
She died of uterine cancer in 1852 at 36 — the same age as her father — and was buried, at her request, beside him. Her notes were largely forgotten until the 1950s, when computer pioneers rediscovered them.
In 1980 the US Department of Defense named its new programming language 'Ada' in her honor. Every October, Ada Lovelace Day celebrates women in science and engineering — for the woman who saw the software age a century before the hardware arrived.
