1. A method of computer controlling a process in an electro-mechanical system having a plurality of controllable components, the method comprising: (a) storing a plurality of component objects each corresponding to one of said components and comprising data which is indicative of an activation state and/or a feedback state of the component to which it relates; (b) storing a plurality of operation objects each comprising an indication of an operation type to be carried out in relation to a component and a reference to a component object identifying said component; (c) storing a plurality of process steps each of which comprises a reference to one or more of said operation objects; and (d) sequentially processing a plurality of said process steps, each process step being processed by: (i) following the or each reference to an operation object, (ii) determining from the operation object the operation type and the component object referenced by said operation object; and (iii) performing a data operation on said component object effective to cause said operation to be carried out in relation to said identified component; whereby a system controller is configured to address said components in order to activate components in dependence on the activation state of corresponding component objects and to update the feedback states of component objects in dependence on signals received from said components.