Diff — Grace Hopper

{{infobox

| title = Grace Hopper

| image = grace-hopper.jpg

| caption = Commodore Grace Hopper, USN — the official "covered" portrait

| born = 9 December 1906, New York City

| died = 1 January 1992, Arlington, Virginia (aged 85)

| service = US Navy (WAVES) 1943–1986 — oldest active-duty officer at retirement

| rank = Rear Admiral (lower half)

| education = Vassar; PhD mathematics, Yale 1934

| known_for = First compiler (A-0) · COBOL advocacy · "debugging"

| machines = Harvard Mark I · UNIVAC

| nicknames = "Amazing Grace" · "Grandma COBOL"

| honors = USS *Hopper* (DDG-70) · Presidential Medal of Freedom (2016)

}}

**Grace Brewster Murray Hopper** (9 December 1906 – 1 January 1992) was a mathematician, a Navy rear admiral, and the person who proved a computer could write its own program. She built the first compiler, popularized the word "debugging," championed [[COBOL]] into existence as a standard, and spent forty years telling anyone who would listen that computers belonged to people, not priesthoods. The fleet named a destroyer for her.

## Before the Navy

Grace Murray earned her doctorate in mathematics from **Yale in 1934** — one of the few women then holding a math PhD — and taught at **Vassar**, her alma mater. When the United States entered the Second World War she tried to enlist and was rejected on every technicality available: too old at 37, fifteen pounds under the Navy's minimum weight, and — officially — too valuable as a mathematics professor to release. She obtained waivers for all of it and joined the **WAVES** in December 1943, graduating first in her class at Smith College.

## Harvard and the Mark I

Her first assignment was luck disguised as an order: the **Bureau of Ordnance Computation Project** at Harvard, under Commander **Howard Aiken**, running the **Mark I** — IBM's Automatic Sequence Controlled Calculator, a fifty-one-foot relay machine of switches, gears, and five hundred miles of wire, driven by punched paper tape.

Hopper became one of its first three programmers and wrote its operating manual. The Mark I's programmers coded long arithmetic sequences in a notation somewhere between mathematics and machine code — problems like the rocket-trajectory and implosion-modeling calculations the Navy needed. It was punishing, glorious work; Aiken was famously hard to please, and Hopper famously unafraid of him. She stayed at Harvard's Computation Laboratory after the war as a research fellow — until private industry offered something Harvard couldn't: a machine you could *buy*.

## The moth — told honestly

[[File:first-bug-1947.jpg|right|320px|The logbook page, 9 September 1947 — "First actual case of bug being found"]]

In September 1947, operators of Harvard's **Mark II** traced a malfunction to a moth trapped in relay #70 and taped the insect into the logbook: "*First actual case of bug being found.*" Hopper didn't find the moth, didn't log it — but she told the story for the rest of her life, and through her the engineering term *bug* (which Edison had used in the 1870s) became *debugging*: the word programming still uses. The logbook page sits in the Smithsonian, moth and all.

## The compiler nobody believed

In 1949 Hopper joined the Eckert–Mauchly Computer Corporation — soon part of Remington Rand — home of **[[UNIVAC_I|UNIVAC]]**, the first commercial American computer. There, in 1952, she did the thing people said couldn't be done.

Programmers then wrote raw machine code: numeric opcodes, absolute addresses, and hours of copying errors. Hopper's insight was that *the machine could do the tedious part*. Her **A-0 system** read a program written as symbolic calls — "get subroutine number 217 from the tape library, put it here, wire it up thus" — and produced runnable machine code. A program writing a program. She called it a **compiler**.

The reaction was disbelief and worse: colleagues argued a computer *couldn't* write programs, that code had to be hand-crafted, that her approach would produce inefficient machine instructions. She later said, plainly: *"Nobody believed that. I had a running compiler and nobody would touch it. They told me computers could only do arithmetic."* A-0 became A-2, then **MATH-MATIC** and **FLOW-MATIC** — the first English-like business language, and the direct ancestor of [[COBOL]]. Every compiler, interpreter, and transpiler since — including the one that builds [[AdaLogic BASIC]] — stands on her A-0.

## COBOL and the standards war

COBOL itself was designed by the **CODASYL committee** in 1959–60 (its own page [[COBOL|tells that story]]), but Hopper's fingerprints are everywhere: FLOW-MATIC proved English-like syntax could work, she advised the committee, and then she did the unglamorous part that made COBOL real — **enforcement**. The Navy ran validation tests for COBOL compilers, refusing to certify non-conforming ones, which is a large part of why "COBOL" meant the same language on every vendor's machine. Languages die by dialect; Hopper strangled the dialects.

She collected an actual **tombstone** engraved "COBOL" — a gift joking about the language's predicted demise — and kept it in her office, pointing at it every time someone declared COBOL dead. It outlived every eulogist.

## Amazing Grace

[[File:hopper-commodore.jpg|left|300px|Promotion to Commodore, 1983 — the Navy's oldest officer, still lecturing]]

Hopper's second career was teaching the future to people who didn't believe in it yet. Her props were famous:

- She handed out **"nanoseconds"** — foot-long wires, the distance light travels in a billionth of a second — to executives who asked why satellite communication took so long. (For a "picosecond," she offered a packet of pepper: the space between the flakes.)

- Her office clock ran **backwards**. Asked why, she'd say it was a reminder that arbitrary conventions can be changed.

- Her standing orders to young officers: "*It's easier to ask forgiveness than it is to get permission*" — and "*the most dangerous phrase in the language is 'we've always done it this way.'*"

She retired from the Navy in **1966** — and was recalled within the year, "temporarily," for what became nineteen more years of service. When she finally retired in **1986**, aboard the USS *Constitution* — the Navy's oldest commissioned ship — she was, at seventy-nine, its oldest active-duty commissioned officer.

Her private life was quiet: a marriage ended in 1945, she kept her husband's name, never remarried, had no children, and gave the Navy and its sailors the devotion a family might have gotten. The lecture circuit made her, in her seventies, an improbable celebrity — the admiral in dress whites explaining computers to rooms full of people who feared them.

## Legacy

- **USS *Hopper* (DDG-70)** — the guided-missile destroyer commissioned in 1997, the second Navy ship named for a woman

- **Presidential Medal of Freedom**, awarded posthumously in 2016

- The **Grace Hopper Celebration** — the world's largest gathering of women in computing, running since 1994

- **Hopper College**, Yale — renamed for her in 2017

- And the word **debugging**, used by every programmer who ever lived, whether they know her name or not

Her real epitaph is the compiler: the idea that humans write *intent* and machines write *instructions*. Everything in [[History of Programming|the language era]] — FORTRAN, COBOL, ALB — descends from it.

## See also

- [[COBOL]] · [[History of Programming]]

- [[The first programmers]] — her ENIAC contemporary, Betty Holberton, co-edited COBOL's spec

- [[Alan Turing]] · [[Bletchley Park]]

- [[IBM]] · [[Punched card]]

[[Category:People]]

[[Category:Programmers]]

[[Category:History]]

[[Category:Languages]]