Computers developed from mechanical calculating machines. One of the earliest mechanical machines, still used today, is the abacus, a wooden frame with parallel rods on which beads are strung.
In 1642, Blaise Pascal, while still a teenager, invented a simple mechanism for adding and subtracting. In the mid 1850’s, Charles Babbage had the idea of a machine that would undertake any kind of calculation, driven by steam, the entire program of operations would be stored on a punched tape. It was never built, but the idea is used in modern computers. Babbage enjoys the title of “the father of the computer”.
Punched cards were a way of programming or giving instructions to a machine. It was used to do automated pattern weaving on a loom. Cards with holes directed threads on the loom, with wire hooks passing through the holes to grab and pull specific colored threads to be woven into the cloth.
The use of punched cards was used in the 1890 United States Census. Metal pins in the machine’s reader passed through holes punched in the card, momentarily closing an electric circuit. The resulting pulses advanced counters assigned to details, such as income and family size.
The company that developed this tabulated machine became IBM in 1924. Their 80 column, 7.375 inches by 3.25 inches, card became the standard of the industry. The reminder: “Do not fold, spindle, or mutilate” was printed on each card.
The earliest programmable electronic computer was the brainchild of Alan Turing, built by Newman and Flowers in 1943, called “Colossus”. It had 1500 vacuum tubes and frequently broke down, but the British were able to break the German code generated by their “Enigma” machines.
The United States made a mammoth computer using vacuum tubes and drum memories, called ENIAC, right after WWII. It had over 17,000 vacuum tubes, (a really fancy light bulb), weighed 30 tons, measured 100 feet long, 8 feet high, and 3 feet deep, and used over 15 kilowatts of power. Los Alamos labs used an ENIAC to develop the hydrogen bomb in the early 1950’s.
The transistor was developed in 1948 and greatly reduced the size, complexity, and power requirements of electronics, and increased the speed at the same time. In the early 1960’s, silicon chips packed thousands of transistors and circuit components onto a wafer.
There is some new stuff coming out. Gallium arsenide has greatly increased switching speed. Organic polymers, used for liquid crystal panels and other flat screen displays, has nvast potential. Optical chips, that push light around instead of electrons, have shown promise.
To answer the question “Who invented the computer?”, a honest answer would be “a whole bunch of people”. It was a steady progression of knowledge, research, advancing technology, and material development by a host of smart and motivated people.