Over time the idea of what "computing can do" has evolved to a point that now a days it is even used to "implement the behaviour of a mechanical system" rather than just being a tool to do data processing. The problem of building the mechanical system basically boils down to what all components and what all connections between the components are required to achieve the desired behaviour. This would be what a mechanical engineer would think about. A software engineer on the other hand would think about the components required and the algorithm that would control the components to achieve the desired behaviour. Both approaches have their pros and cons but as the desired behaviour get more and more complex, the algorithmic approach tends to be more simple and feasible.