The first incantation of modern computers started with the first mechanical computers. Initially these tools were developed to help with mathematical calculations. Most early devices were mechanical analogues of the Arithmetic Unit of a modern computer - they were mostly just devices for performing numerical calculations. The missing factor in almost all of these is the stored program concept, i.e. the human had to provide the algorithm (method) and the program 'store'. In this section we will review some of the earliest Mechanical computers and what function they served at the time of their discovery.