user to input instruction list i.e. logic code,
That does notg make it a PLC.

PLC users can (to mvarious degrees) understand and modify ladder logic, to make a PLC user 'program' in a different way put you back in uC control unit.

Erik

Uc controllers are not 'bad' that is not my point, the poit is that if you replace a PLC with a uC controller, that does not make the uC controller a PLC.