The next major advances and the real beginning of the computer age took place in the mid 1940s. Prior to that time the definition of computer was, "a person who performs computations". Part of the war effort revolved around human computers (women) performing calculations for bomb trajectories.

These calculations required extreme precision and took quite a bit of time. One of the first computers, the ENIAC, was built to automate the calculations of these trajectories.. The inventors of the ENIAC went on to create the UNIVAC, the first commercial computer.

First generation computers were characterized by the fact that operating instructions were made-to-order for the specific task for which the computer was to be used. Each computer had a different binary-coded program called a machine language that told it how to operate. This made the computer difficult to program and limited its versatility and speed. Other distinctive features of first generation computers were the use of vacuum tubes (responsible for their breathtaking size) and magnetic drums for data storage.