The Harvard Mark I, also known as the IBM Automatic Sequence Controlled Calculator, was one of the first electromechanical computers. Developed by Howard Aiken and built by IBM, it was completed in 1944. The machine was about 51 feet long and used over 750,000 components, including switches and relays, to perform calculations. The Harvard Mark I could execute basic arithmetic operations and was capable of handling complex calculations automatically. It played a significant role in scientific research during its time, particularly in the development of the atomic bomb as part of the Manhattan Project.