Thirdly, Turing was interested in the very idea of an algorithm, and in the limits of what tasks it was possible to solve algorithmically. Thus, he developed the model of computation known as a Turing machine . This is still the most general model of computation and it is conjectured in the Church-Turing Thesis that any problem that can be solved algorithmically can be solved by a Turing Machine. Fourthly, Turing is famous because of his work in conceiving a machine that could simulate intelligence. The Development of Electronic Computing Machines Up until the early 1940s the large computers that were built were either mechanical or electromechanical, relying on relays for the switching mechanisms required.
Relays are essentially switches operated by an electromagnet.
These machines were large and slow. One example is the machines built by the German inventors Konrad Zuse and Helmut Schreyer. You can examine the basic chronology of events and related discussions in the Web documents here. This became known as the Harvard architecture as opposed to the von Neumann architecture which has been the dominant approach used in most moderm microprocessors. We will look closely at the von Neumann architecture in the next module.