ENIAC Trivia
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42 free ENIAC trivia questions with answers — technology quiz, new questions added Sep 2026.
This ENIAC trivia quiz is about the 30-ton, 18,000-tube machine that the press called a 'Giant Brain' when it was unveiled at the University of Pennsylvania in February 1946. It covers how the Army came to fund John Mauchly and J. Presper Eckert's secret Project PX to speed up artillery firing tables, what the machine was actually made of, how fast it could add, multiply and divide, and how often a tube burned out. A large part of the quiz is devoted to the six women, Kay McNulty, Betty Jennings, Betty Snyder, Marlyn Wescoff, Fran Bilas and Ruth Lichterman, who worked out how to program the thing with cables and switches, and who were left off the guest list for its own dedication dinner. It also asks about ENIAC's first real job for the hydrogen bomb, its role in the Monte Carlo method, its 1948 conversion into a slow stored-program computer, its retirement at Aberdeen in 1955, and the 1973 court ruling that voided its patent in favour of John Atanasoff. Difficulty runs from easy questions about what the acronym stands for to expert questions on accumulators and ring counters. Every answer was verified against the Wikipedia articles on ENIAC, J. Presper Eckert and Jean Bartik.
30 of 42 questions with answers and explanations. Play the quiz
Q 01What does the acronym ENIAC stand for?
Electronic Numerical Integrator and Computer
Electronic Numerical Integrator and Computer: it was designed to compute artillery firing tables for World War II, but it was finished too late to be used in the war.
Q 02Which computer built by ENIAC's inventors called Eisenhower's 1952 landslide on CBS television?
UNIVAC
UNIVAC came within about 3 percent of Eisenhower's popular vote on election night, a publicity boost that made the new computer famous.
Q 03ENIAC read its numbers from punched cards using equipment made by which company?
IBM
IBM made ENIAC's card reader and card punch, and with so little internal memory, the machine relied on punched cards as its external storage.
Q 04What was the subject of ENIAC's first program?
The feasibility of the hydrogen bomb
The feasibility of the hydrogen bomb: though ENIAC was designed to compute artillery tables, its first real job, in December 1945, was a calculation for the H-bomb.
Q 05Where was ENIAC built and formally dedicated on February 15, 1946?
Penn's Moore School
Penn's Moore School built ENIAC in secret for the Army, which kept the machine under wraps until months after World War II had ended.
Q 06What nickname did the press give ENIAC when it was unveiled?
Giant Brain
Giant Brain was the press's name for ENIAC, yet the women who programmed it were not even introduced when the machine was unveiled in 1946.
Q 07How did ENIAC's engineers make its vacuum tubes last longer?
Running them at reduced power
Running them at reduced power stretched tube life, which mattered because failing tubes could leave the machine out of action for long periods.
Q 08Eckert and Mauchly's BINAC computer was built for which aircraft maker, later prime contractor for the B-2 stealth bomber?
Northrop
Northrop took delivery of the BINAC, but the machine never worked properly once it got there.
Q 09About how many vacuum tubes did ENIAC contain?
18,000
About 18,000: with so many, switching ENIAC off and on almost guaranteed a blown tube, so it was left running continuously.
Q 10How much electricity did ENIAC consume?
150 kW
150 kW is the usual figure, though Army reports gave up to about 200 kW, and all that power turned into heat that needed forced-air cooling.
Q 11Which room-sized analogue machine was the Army's main trajectory calculator before ENIAC?
The differential analyzer
The differential analyzer was the standard tool for firing tables, but it was too slow for wartime demand, and that backlog led to ENIAC.
Q 12How many simple additions or subtractions per second could an ENIAC accumulator perform?
5,000
With 5,000 additions a second, ENIAC could compute a 60-second shell trajectory in about 30 seconds, faster than the shell itself could fly.
Q 13Eckert's 1944 memory design for later computers stored pulses as sound waves in which liquid?
Mercury
Mercury: pulses travelled through the tank as sound waves and were reshaped and fed back in, and his BINAC computer used that memory.
Q 21How were the ENIAC programmers classified by the Army, despite holding mathematics degrees?
Subprofessionals
Subprofessionals was the Army's label for the women computers, yet they taught themselves to program ENIAC with no manual to follow.
Q 22A historian once dismissed the women in ENIAC press photos as what?
Refrigerator ladies
Refrigerator ladies was a historian's dismissive guess about the women in the photos; undergraduate Kathy Kleiman later tracked them down and recorded their stories.
Q 23After leaving their university in 1946, ENIAC's inventors won a crucial $300,000 contract from which agency?
The Census Bureau
Q 14Most computers work in binary, but which number system did ENIAC's arithmetic use?
Decimal
Decimal: ENIAC counted pulses on rings of ten positions, electronically copying the digit wheels of a mechanical adding machine.
Q 15Eckert said ENIAC was about a thousand times faster than which electromechanical computer, completed in 1944 for the US Navy?
The Harvard Mark I
The Harvard Mark I ran on relays, shafts and clutches, and ENIAC's all-electronic design let its 1946 demonstration leave that machine far behind.
Q 16After engineers improved reliability, about how often did one of ENIAC's vacuum tubes fail?
About every two days
About every two days, and the maintenance team learned to track down and replace the failed tube in about 15 minutes.
Q 17In 1950, Eckert and Mauchly's struggling computer company was bought by a firm originally known for making what?
Typewriters
Typewriters: the buyer kept Eckert on, and he went on to become one of its executives.
Q 18How was a new program originally entered into ENIAC?
By plugging cables and setting switches
By plugging cables and setting switches, which meant days of work for each new problem before a single calculation could run.
Q 19How many women made up ENIAC's original team of programmers?
Six
Six, and their role went largely unrecognised until the 1990s, when the six were finally honoured and inducted into a technology hall of fame.
Q 20For ENIAC's 1946 public debut, its small neon indicator bulbs were covered with halves of what?
Ping-pong balls
Ping-pong balls: the flashing panels made such an impression that this was how films and TV pictured computers for decades.
The Census Bureau went on to receive the company's first finished business computer in 1951, the machine that contract helped pay for.
Q 24To which Army site was ENIAC moved in 1947, where it ran until 1955?
Aberdeen Proving Ground, Maryland
Aberdeen Proving Ground, Maryland, is where ENIAC served as the Army's main computing engine for most of the next decade, turning out its ballistic tables.
Q 25ENIAC was retired in October 1955 in favour of which two more efficient computers?
EDVAC and ORDVAC
EDVAC and ORDVAC took over its work, and ENIAC's retired panels were later split among museums and universities.
Q 26Which mathematician wrote the 1945 'First Draft' memo that spread the stored-program computer design?
John von Neumann
John von Neumann was the memo's only named author, so the design became known as von Neumann architecture, leaving Eckert and Mauchly without the credit.
Q 27In 1953, ENIAC finally gained a 100-word internal memory built from what?
Magnetic cores
Magnetic cores, in a unit built by the Burroughs Corporation, gave ENIAC fast internal storage where punched cards had been too slow.
Q 28Which statistical technique first ran fully automatically on ENIAC in 1948?
The Monte Carlo method
The Monte Carlo method grew, Stanislaw Ulam recalled, from wondering about his chances of winning at solitaire while recovering from an illness.
Q 29Which 1973 court case voided the ENIAC patent and named John Atanasoff inventor of the electronic digital computer?
Honeywell v. Sperry Rand
Honeywell v. Sperry Rand ended with Judge Earl Larson ruling that Eckert and Mauchly had derived the computer from Atanasoff's work, which Mauchly examined in 1941.
Q 30Which British machine ran its first program in June 1948, becoming the first computer to run a program held in electronic memory?
The Manchester Baby
The Manchester Baby's design grew into a full-scale machine that paved the way for early commercially available computers.