1. A method for operating a data processing device while using compressed data, comprising: loading a non-compressed boot program from a first data memory into a first volatile working memory; executing said boot program; copying, initiated by said boot program, of a compressed application program from a second data memory into a second volatile working memory with simultaneous decompression of said application program, starting said application program through said boot program; and wherein a first non-volatile memory of said data processing device is used as said data memory of said boot program, and a second non-volatile memory of said data processing device is used as said data memory of said application program.