Howard Aiken was an American physicist and a pioneer in computing, being the original conceptual designer behind IBM's Harvard Mark I computer. Aiken studied at the University of Wisconsin–Madison and later obtained his PhD in physics at Harvard University in 1939. During this time, he encountered differential equations that he could only solve numerically. He envisioned an electro-mechanical computing device that could do much of the tedious work for him called the Harvard Mark I. With engineering, construction, and funding from IBM, the machine was completed and installed at Harvard in February, 1944. In 1947, Aiken completed his work on the Harvard Mark II computer. He continued his work on the Mark III and the Harvard Mark IV. The Mark III used some electronic components and the Mark IV was all-electronic. The Mark III and Mark IV used magnetic drum memory and the Mark IV also had magnetic core memory.