Diff — Betty Jennings

{{infobox

| title = Betty Jean Jennings Bartik

| image = betty-jennings.jpg

| caption = Betty Jennings Bartik — University of Pennsylvania portrait (public domain)

| born = 27 December 1924, near Stanberry, Missouri

| died = 23 March 2011, Poughkeepsie, New York (aged 86)

| education = Northwest Missouri State Teachers College, mathematics, 1945 — its only math graduate

| known_for = One of [[The first programmers|the six ENIAC programmers]]; lead programmer of BINAC and UNIVAC I

| programmed = ENIAC · BINAC · UNIVAC I — all three pioneering machines

| famous_moment = Led ENIAC's public demonstration, 15 February 1946

| memoir = *Pioneer Programmer* (2013)

| honors = WITI Hall of Fame (1997) · IEEE Computer Pioneer Award · Computer History Museum Fellow

}}

**Betty Jean Jennings Bartik** — born **Elizabeth Jean Jennings** (27 December 1924 – 23 March 2011), called "Jean" after her marriage to distinguish her from teammate [[Betty Snyder]] — was an American mathematician and one of the six original programmers of **ENIAC**. Of the six, she went furthest: she became lead programmer on **BINAC** and **[[UNIVAC_I|UNIVAC I]]**, the first American commercial computers, and is often described as the one who understood ENIAC most completely.

## From the farm to Philadelphia

Jennings was born on a farm in Gentry County, Missouri — the seventh of eight children — and went to a one-room schoolhouse, reportedly riding there on horseback and skipping grades. She put herself through **Northwest Missouri State Teachers College** in Maryville and graduated in 1945 with a degree in mathematics — the school's only math major that year.

IBM interviewed her for a position and turned her down; the oft-told version says the interviewer found her too short. Instead she answered an Army advertisement for "human computers" — women hired to hand-calculate artillery firing tables — and took the train to the University of Pennsylvania's Moore School of Electrical Engineering in Philadelphia. IBM's rejection letter became, in hindsight, the luckiest piece of paper in computing.

## ENIAC

[[File:reprogramming-eniac.png|left|330px|ENIAC being programmed — cables and switches, one function table at a time (US Army photo, public domain)]]

When ENIAC's six programmers were chosen, there were no manuals, no languages, and no teachers — the Army handed them wiring diagrams and access. Jennings learned the machine by studying its blueprints at night, and it showed: she became the one colleagues describe as understanding ENIAC *whole* — every accumulator, every function table, every cable.

Programming meant rewriting the problem physically: a shell's trajectory was decomposed into differential equations, mapped onto ENIAC's twenty accumulators, then realized by running cables between panels and setting thousands of switches. The women worked in pairs — Jennings with [[Betty Snyder]] — and invented the discipline as they went: **flowcharts to plan the routing, subroutines to reuse it, and debugging when the machine disagreed.**

### The demonstration

Jennings was put in charge of the team that staged ENIAC's public unveiling on **15 February 1946**. The machine computed a sixty-second artillery trajectory in about twenty seconds — faster than the shell's flight — while reporters watched. In the press coverage that followed, the six programmers were cropped, forgotten, or misidentified as models posing with the machine. The women who had made the demonstration possible weren't invited to the celebratory dinner.

### Stored-program conversion

In 1948 Jennings co-led, with Richard Clippinger, the conversion of ENIAC to run its instructions from function tables — a primitive **stored-program mode** that made the machine dramatically easier to program and pointed directly at the [[EDVAC report|EDVAC-era]] architecture that was coming. It was one of the first times an existing machine was reconfigured by *reprogramming its own control*, and Jennings was at its center.

## BINAC and UNIVAC

When Eckert and Mauchly left Penn to found their own company, Jennings went with them — the only one of the six to continue as a professional programmer. She became **programming lead on BINAC** (1949), the first true stored-program computer built in America, whose checkout period was so chaotic she reportedly kept it running by feel; and then on **UNIVAC I**, delivered to the Census Bureau in 1951, where she led the programming group and wrote code for the machine's acceptance tests.

She liked to say she was the only person alive who had programmed all three of the era's pioneering machines — ENIAC, BINAC, and UNIVAC. She was probably right.

## After the machines

Jennings married William Bartik in December 1946 and left the industry in 1951 to raise their children — just as the field she had helped invent began to boom. She returned to computing in the 1960s as a technical editor at **Auerbach Publishers**, documenting and standardizing the industry she had helped create, and later worked at Data Decisions.

In 1986, Harvard undergraduate **Kathy Kleiman** tracked down the women in the uncaptioned ENIAC photographs and began the work of restoring them to the record. Jennings embraced the role of witness — she gave talks, taught herself email, and spent her last decades making sure the story was told straight. Her memoir, ***Pioneer Programmer***, appeared in 2013 — the fullest first-person account of the six.

## Legacy

- Inducted into the **Women in Technology International Hall of Fame** in 1997 with the other five ENIAC programmers

- **IEEE Computer Pioneer Award** (2008) and **Computer History Museum Fellow** (2008)

- Honorary doctorate from Northwest Missouri State, which renamed a museum and a fellowship for her

- Her memoir remains the primary source for how ENIAC was actually programmed — the technique, the teamwork, and the erasure

She died in Poughkeepsie, New York, on 23 March 2011 — having lived long enough to be transformed in public memory from an anonymous "refrigerator lady" to a founding programmer of the computer age.

## See also

- [[The first programmers]] — the six together

- [[Kay McNulty]] · [[Betty Snyder]] · [[Marlyn Wescoff]] · [[Fran Bilas]] · [[Ruth Lichterman]]

- [[Bletchley Park]] · [[Grace Hopper]]

- [[History of Programming]]

[[Category:History]]

[[Category:People]]

[[Category:Programmers]]