Abstract: The apparatus contains a microprocessor circuit, which comprises a preprocessor which is not DMA-capable in itself and a DMA-capable central processor. Both processors can be made to communicate with each other by means of a main memory. This is performed by temporarily cutting off the communication path between said DMA-capable central processor and said main memory, specifically by an artificial DMA request via the address line of said preprocessor, and by establishing instead a communication path between said preprocessor and said main memory. The communication of said preprocessor with said main memory is started after said central processor has sent a return message signal to said preprocessor, whereby it confirms that its own communication with said main memory is completed.

Abstract: Scanning and selection methods and apparatus as well as an electrophotographic printing system employing such scanning and selection apparatus are provided in accordance with the teachings of the present invention. In an exemplary embodiment of the invention a plurality of coded data records containing selection information and a plurality of coded data records to be classified for selection purposes are scanned by code sensing devices. Code information from each of the plurality of coded data records containing selection information is loaded in sequence into memory apparatus to store therein the selection conditions to be imposed upon the plurality of coded data records to be classified for selection purposes. The selection information obtained being directed to a plurality of selection considerations and such sequence being arranged in a manner so that each of the plurality of selection considerations is defined in different areas of the memory apparatus.