This was the earliest era in which computers were specifically engineered to perform calculations, making them quite expensive and primarily accessible to governments, businesses, and major research institutions. For instance, the Harvard Mark I, completed in 1944, was a mechanical/electromagnetic computer used to create ballistics tables for the United States Army.
Basic programmability
Although far inferior to modern languages, the first software was developed during this time, allowing computers to follow stored instruction sets known as programs. John Mauchly, J. Presper Eckert, and Grace Hopper were prominent figures in early computer programming.
Analog computations
These first computers were not completely digital. Many machines used analog computations based on measurements such as voltage or rotation to generate output values rather than using only the discrete, binary system (ones and zeros) of digital computers. These analog-only machines were widely used for scientific functions such as ballistics and aerodynamics.
Electro-mechanical technology
Early computers depended on electro-mechanical technology, such as relays, switches, and vacuum tubes, creating machines that were large, expensive, and required considerable maintenance.
Significant scientific contributions
Despite the limitations of the day, the development and use of computers in the 1940s ushered in a new era of scientific achievements and the dawn of the digital age. The Colossus computer played a crucial role in British code breaking during World War II, and the ENIAC computer, designed by Mauchly and Eckert, was instrumental in performing advanced calculations for the United States Army.