When trying to figure out when the first computer was invented, it can all depend on whom you ask. A historian might tell you that the first computer was the abacus, which was invented in Asia about 5000 years ago. However, the first modern computer was actually invented during World War II when a team of scientists and engineers at the University of Pennsylvania invented a general-purpose electronic digital calculator know as ENIAC (Electronic Numerator, Integrator, Analyzer, and Computer).
It consisted of 18,000 vacuum tubes and it was capable of adding 5,000 ten-digit decimal numbers per second. It also contained 7,200 crystal diodes, 1,500 relays, 70,000 resistors, 10,000 capacitors and around 5 million hand-soldered joints. It weighed approximately 30 short tons, took up about 1800 square feet (167 m²), and consumed 150 kW of power.
Several electronics experts of the day had predicted that tube failures within the ENIAC would occur so frequently that the machine would not be practical to use. In truth, they did have several tubes burn out each day, however, it still functioned about half the time. Most of the tube failures occurred during the warm-up and cool-down periods, when the tube heaters and cathodes were under thermal stress. For a truly “low-tech” solution, the engineers were able to reduce the downtime by simply leaving it turned on all the time, and reducing the tube failure to the more acceptable rate of one tube every two days.
It was the first large-scale, electronic, digital computer capable of being reprogrammed so it could solve a variety of computing problems. The ENIAC was originally designed to calculate artillery firing tables for the U.S. Army's Ballistics Research Laboratory. However, some of the first problems that were run on the ENIAC were related to the design of the hydrogen bomb. The ENIAC was definitely a revolutionary development, which at the time, was light years ahead of any other calculators.
However, ENIAC was not a computer in the strict meaning of the term. Its major problem was that it could not store a program. In other words, it could not store a list of list of commands that tell a computer what to do. After the invention of ENIAC in 1944, another contract was issued for the design of the EDVAC (Electronic Discrete Variable Computer). This was a computer that could be used to store programs in it. It may seem simple now, but at the time, it was impossible to think that you could store commands in a machine.
The EDVAC was built for the U.S. Army's Ballistics Research Laboratory at the Aberdeen Proving Ground by the University of Pennsylvania. It had a memory capacity of 1,000 44-bit words, which was later set to 1,024 words, giving it a memory capacity of about 5.5 kilobytes. It had almost 6,000 vacuum tubes and 12,000 diodes, and consumed 56 kW of power. It covered 490 square feet and weighed around nine short tons. The full complement of operating personnel required to run it was thirty people for each eight-hour shift.
It was a huge improvement over the ENIAC in many ways. For instance, the EDVAC had a memory that held information and data allowing it to be stopped and started at various times. It also had a CPU (central processing unit), which is something used in modern computers today. The EDVAC was also capable of running error-free for at least eight hours at a time.
The ENIAC may have been the first functional large-scale, electronic, digital computer. However, some may say that it was the EDVAC that truly gave birth to the computer revolution with its improvements over the ENIAC that led to the modern computers used today. So even if you do not agree that the ENIAC was the first computer, it certainly led to the invention of one, and today's computers are its direct descendants.