The Computer is not truly mechanism and is the logical approach - a set of on and offs. 'Computer' here is taken to be defined the Turing Machine that may be supposed the ideally stated approach.
'Computer' is not really physical and is the ideally stated method that can be made in many ways. The abstract modus operandi is defined the Universal Machine that may be considered the logical approach and can simulate any machine. The formal modus operandi is defined the Turing Machine that may be supposed the logical approach performing a computation.
See also Inscription,