A data processor apparatus comprises a plurality of processor elements, a memory having a plurality of parts, and a first switching element associated with the first processor element for switchably coupling the first processor element to its associated memory part for at least one of read and write access. The first switching element has an input port, an output port, a first port being coupled to a second switching element, the second switching element being associated with the second processor element for switchably coupling the second processor element to its associated memory part, a second port being coupled to a third switching element, the third switching element being associated with the third processor element for switchably coupling the third processor element to its associated memory part, a first switch means for selectively coupling the first port to one of the input port and the output port, and a second switch means for selectively coupling the second port to one of the input port and the output port.