Provided is an apparatus (TFDC) for operating a software-configured processing unit (SDS) for a device, in particular a field device (TFD), wherein the apparatus, according to a prescribed and/or prescribable architecture, includes at least one processor (CPU) and a number of hardware units, having: a security unit (IOS; MS) configured to cause a change in the arrangement of the data bit sequence of at least one data stream provided and/or routed to the processing unit (SDS) to protect the hardware units from manipulation. The processing unit is trustworthy, i.e., is protected from manipulation and attack from the outside. The data stream arrives at the device. A “number” here and above denotes a number of one or more.