An Inherently Fail Safe processing or control apparatus having a first processing unit with - a first processor and a memory containing a predetermined data processing and/or control program; - at least one input port for input data received from at least one remote unit; - at least one output port for output data to be transmitted to at least one remote unit under the control of said first processing unit; characterized in that - the first processing unit further comprises means for generating unique codes for functional check of the processing or receiving or transmitting steps being performed (so-called checkwords) and a port for the transmission of the checkwords generated at each step; - a functional checker and protection unit is further provided, which consists of a fail-safe second processing unit, with a memory containing a program for checking the functional steps of the first processing unit and a program for checking the correctness of functional control codes (so called checkwords) and the time sequence thereof. - which functional checker and protection unit communicates, by a transmit receive port, with the first processing unit, and generates enabling signals for it when checkwords are correct; - while the said functional checker and protection unit generates signals for disabling the activity of the first processing unit and/or for forcing the first processing unit to the transmission of predetermined output data for fail-safe remote unit control, or the said functional checker and protection unit generates itself predetermined output data for fail-safe remote unit control or signals for enabling/disabling vital functions of the remote unit or of the first processing unit which are transmitted to the remote unit and/or to the first processing unit; which functional checker and protection unit is provided with two independent processors, one of the two processors for running the said program for checking the functional steps of the first processing unit and the other of the said two processors for running the said program for checking the correctness of functional control codes (so called checkwords) and the time sequence thereof. - a first processor and a memory containing a predetermined data processing and/or control program; - at least one input port for input data received from at least one remote unit; - at least one output port for output data to be transmitted to at least one remote unit under the control of said first processing unit; - the first processing unit further comprises means for generating unique codes for functional check of the processing or receiving or transmitting steps being performed (so-called checkwords) and a port for the transmission of the checkwords generated at each step; - a functional checker and protection unit is further provided, which consists of a fail-safe second processing unit, with a memory containing a program for checking the functional steps of the first processing unit and a program for checking the correctness of functional control codes (so called checkwords) and the time sequence thereof. - which functional checker and protection unit communicates, by a transmit receive port, with the first processing unit, and generates enabling signals for it when checkwords are correct; - while the said functional checker and protection unit generates signals for disabling the activity of the first processing unit and/or for forcing the first processing unit to the transmission of predetermined output data for fail-safe remote unit control, or the said functional checker and protection unit generates itself predetermined output data for fail-safe remote unit control or signals for enabling/disabling vital functions of the remote unit or of the first processing unit which are transmitted to the remote unit and/or to the first processing unit;