ENIAC, the first general purpose electronic digital computer, used which component for switching?

The correct answer is B, second. The generations of computers are named for the switching device they use, and the second generation, running from the late 1950s into the early 1960s, replaced the bulky vacuum tube with the transistor, which had been invented at Bell Laboratories in 1947. Transistor machines were smaller, cooler, cheaper and far more reliable, and IBM 1401 and IBM 7094 are the usual examples. Option D is wrong because the first generation used vacuum tubes or valves, as in ENIAC and UNIVAC-I. Option C is wrong because the third generation moved on to integrated circuits, many transistors on a single chip, as in the IBM 360. Option A is wrong because the fourth generation is defined by the microprocessor and very large scale integration, which began with the Intel 4004 in 1971.

The correct answer is C, third generation. The IBM System/360, announced in 1964, was built around integrated circuits, and the integrated circuit is exactly what defines the third generation of computers; the series is also remembered for introducing a single compatible family of machines of different sizes. Option B is wrong because the first generation used vacuum tubes, the era of ENIAC, EDVAC and UNIVAC-I. Option A is wrong because the second generation used discrete transistors, the era of the IBM 1401 and IBM 7094. Option D is wrong because the fourth generation is the age of the microprocessor and the personal computer, which began after the Intel 4004 of 1971 and gave us the IBM PC of 1981. Integrated circuits were invented in 1958 by Jack Kilby and Robert Noyce.

The correct answer is B, Charles Babbage. Babbage designed the Difference Engine in 1822 and then the Analytical Engine, a general purpose mechanical computer with a store for numbers, a mill for arithmetic, punched card input and printed output, which is the plan of a modern computer drawn a century before one could be built; for that he is called the father of the computer. Option A is wrong because Blaise Pascal built the Pascaline of 1642, a mechanical adding machine but not a programmable computer. Option C is wrong because Alan Turing is called the father of computer science for the theoretical Turing machine of 1936. Option D is wrong because John von Neumann gave the stored program concept and the architecture named after him, a later contribution.

The correct answer is C, Blaise Pascal. The French mathematician Blaise Pascal built the Pascaline in 1642 to help his father with tax calculations; it worked with toothed wheels and could add and subtract, and the programming language Pascal is named in his honour. Option A is wrong because Gottfried Leibniz built the Stepped Reckoner in 1673, an improvement that could also multiply and divide, and he gave the binary number system. Option B is wrong because John Napier published logarithms in 1614 and devised the calculating rods called Napier’s bones. Option D is wrong because Joseph Marie Jacquard built a punched card loom in 1801; his cards influenced computing but his machine wove cloth rather than doing arithmetic. Pascal was only nineteen when he built the machine, and its wheels carried a tooth that passed the carry on to the next digit.

The correct answer is A, Ada Lovelace. Ada Lovelace, the daughter of Lord Byron, worked with Charles Babbage on the Analytical Engine, and the notes she published in 1843 include a step by step sequence for computing Bernoulli numbers on it, which is recognised as the first computer program; a programming language, Ada, is named after her. Option B is wrong because Grace Hopper came a century later and is remembered for the first compiler, for COBOL and for popularising the word debugging. Option C is wrong because Dennis Ritchie created the C language and co-created Unix in the 1970s. Option D is wrong because Konrad Zuse built the Z3 in 1941, a machine rather than a program. Lovelace also saw that such an engine might one day work on symbols and music and not on numbers alone.