February 14, 1946

Unveiling of ENIAC

ENIAC is unveiled to the press at Penn's Moore School

Two of the women who had wired the machine prepared the test run that stunned the reporters on 14 February 1946. None of the six was mentioned at the unveiling.

14 February 1946: the announcement

On 14 February 1946 the press was invited to the Moore School of Engineering in Philadelphia for ENIAC's public unveiling. The University of Pennsylvania dates the machine's original announcement to that day; the University of Michigan calls it the official public unveiling.

Arthur Burks demonstrated by adding 5,000 numbers in about one second, then ran a shell-trajectory calculation representing a 30-second flight. ENIAC finished it in 20 seconds — faster than the shell.

The six women who had configured and wired the machine were not mentioned at the unveiling, although two of them had prepared the test run used to impress the media.

And 15 February: the dedication

The formal dedication is generally dated to the following day. Major General Gladeon M. Barnes dedicated ENIAC at the University of Pennsylvania by pressing a button that switched it on, and the guests then went through to the Moore School to see the demonstration — including a ballistic-trajectory program developed by Betty Snyder and Jean Jennings, which made the machine's speed visible to the room.

The dedication dinner listed 110 guests. The six women who programmed ENIAC were not honoured as the male engineers were, and were apparently excluded from it.

Thomas Haigh's archival reconstruction in ENIAC in Action identifies 1 February and 15 February as the two documented debut events: reporters had already attended an embargoed preview on 1 February, where Arthur Burks and Kite Sharpless demonstrated addition, multiplication, powers, trigonometric tables and part of the Los Alamos calculation at 5,000 additions, or 50 multiplications, in one second. The original War Department release was marked for radio use after 7 p.m. on 15 February and for newspaper release on 16 February, which added to the confusion over the date.

The machine on show

Penn describes ENIAC as filling a room 30 by 50 feet, weighing about 30 short tons and running on 17,468 vacuum tubes — commonly rounded to 18,000 — at a construction cost of around half a million dollars.

Problems were set up by routing control through cables, plugboards and function-table switches; ENIAC was programmable, but did not yet hold its programs in writable internal memory. Commissioned to speed artillery firing-table calculations, it was finished after the war, and its first practical work was instead a classified Los Alamos problem that probably involved hydrogen-bomb ignition calculations — the exact program remains classified. Accounts of when it first ran differ, most placing it on 10 December 1945 and some in November.

So the reporters who watched ENIAC beat a shell to its target were being shown a machine that had already spent two months on a problem nobody in the room would name.

Sources

Researched 23 Aug 2026 6 sources 2 audit passes, 2 issues open Date disputed

How this was checked

Researched from the web into a fact sheet, rewritten from that sheet, then audited against it by a different model. How the pipeline works →

Date disputed. Sources disagree about when this happened.

What the sources leave uncertain

The listed February 14 date is traditional but poorly aligned with the strongest documentary chronology. Scholarly research identifies an embargoed press preview on February 1 and the formal demonstration and dedication on February 15.
Some institutional and popular accounts nevertheless call February 14 the official unveiling or the date on which secrecy ended. This sheet uses February 15 as the best-supported date for the actual ceremonial public launch.
The original War Department release was marked for radio use after 7 p.m. February 15 and newspaper release on February 16, adding to the confusion.