💻The Greats

Rejected by the Navy for active duty for being underweight, Hopper joined the Naval Reserve in 1943 and was later assigned to program the Harvard Mark I. In September 1947, her Mark II team taped a moth that had jammed a relay into their logbook, noting the "first actual case of bug being found" — Hopper did not coin the word 'bug', but she told the story for decades until it became the field's founding legend.

During Apollo 11's lunar descent in July 1969, the guidance computer began throwing 1202 and 1201 alarms as a misconfigured radar switch flooded it with extra work. Hamilton's team had built the software to shed low-priority tasks under overload rather than crash, so it kept the landing guidance running; Mission Control, primed by a NASA engineer's handwritten alarm cheat sheet, called "go" instead of aborting.

On August 25, 1991, Torvalds posted to the Usenet group comp.os.minix that he was writing "a (free) operating system (just a hobby, won't be big and professional like gnu)". Volunteers around the world began contributing within months. In 2005, after a licensing dispute cut the kernel team off from its existing source-control tool, he wrote Git's core himself in about ten days rather than wait for someone else to build one.

Liskov earned her PhD in computer science from Stanford in 1968, one of the first women in the United States to do so. At MIT she led the team that built CLU between 1974 and 1975, introducing abstract data types years before 'object-oriented programming' was a common phrase. In a 1987 conference keynote she stated what became known as the Liskov Substitution Principle, now the 'L' in the SOLID design principles taught to nearly every engineer.

Lovelace's Note G, the longest of seven notes accompanying her translation of Luigi Menabrea's paper, laid out the Analytical Engine's operation cards to compute Bernoulli numbers, and she caught and corrected an error in the calculation before publication. She died of cancer in 1852 at 36, decades before anyone built a machine that could run what she had written; the programming language Ada, adopted by the US Department of Defense in 1980, was named for her.

Allen grew up on a dairy farm in Peru, New York, without electricity or plumbing, and joined IBM in 1957 mainly to pay off her college debt from teaching. Her 1966 paper 'Program Optimization' introduced graph-based techniques for analysing code that are still taught in compiler courses. She later led PTRAN, a project that taught compilers to find hidden parallelism in old Fortran programs automatically, and became IBM's first female Fellow in 1989.

Matsumoto began sketching Ruby on paper in February 1993, blending pieces of Perl, Smalltalk, Eiffel, Lisp and Ada, and released it publicly in 1995. He has said his goal was to make programmers happy rather than to optimise for the computer, a philosophy the Ruby community turned into its own motto, "Matz is nice, and so we are nice" — a rule about how contributors should treat each other, not just how the language should behave.