The invention relates to a method for operating a data processing device (SPS) as a memory-programmable control unit. In order to attain a rapid processing of entry and/or outlet data with low memory consumption, the process includes the following steps: Reading in entry data (E0 . . . En.n) applying on entry components (E0 . . . En), Storing entry data in a memory (DS) as process image (PAE) of entries such that a bit allocated to each entry (E0.0 . . . En.n) of a memory position (SZ) is set to zero or one, Building up a memory region according to the type of a stack (BIT, ST, BY ST, WST, DWST, QWST) with entry data (E0.0 . . . En.n) required with a subsequent program processing, Loading the entry data (E0.0 . . . En.n) filed in the stack (BITST, BYST, BST, DWST, QWST) into the processor register, Generating outlet data (A0.0 . . . An.n) by servicing a program code with the entry data deposited in the processor register (DX) such that the processor register (DX) contains corresponding outlet data following the processing, Storage of the outlet data contained in the processor register (DX) into memory (DS) as a process image (PAA) of the outlets such that a bit of each memory position allocated to each outlet is set to zero or one, and Transferring the outlet data (A0.0 . . . An.n) stored in memory to an outlet component (A0 . . . An).