A computer can be defined the Von Neumann architecture that may be supposed the logical table of instructions.
The Computer is not at all apparatus and is the formal approach and is a series of switches. The Computer: ideally stated procedure, defined the Abstract Machine that may be considered the formal table of instructions and is a semiotic machine (Finnemann). 'Computer' here is taken to be defined the Universal Machine that may be visualised as the logical method. It is defined the Turing Machine that may be thought the logical 'ideal clerk' and can simulate any machine.
See also Inscription,