'Computer' is not fundamentally mechanical and is the formalized 'ideal clerk' that can be made in many ways. The formalized method is defined the Turing Machine that may be considered the ideally stated method. The Computer is thus defined the Von Neumann architecture that may be supposed the abstract table of instructions and is now networked.
It is defined the Turing Machine that may be thought the abstract set of rules and can simulate any machine.
See also Inscription,