Abstract: A notional two-dimensional array of processors is subdivided into a plurality of identical sub-arrays constituted by respective sub-array boards arranged in a stack in which the order of the sub-array boards is determined as if they had been arranged, as the array, in a sheet which is then folded along lines running between the sub-array boards. Interconnections are provided between the sub-array boards as if extended across the fold lines such that none of the interconnections crosses with any other. If the sub-array boards are oriented differently from their orientation as determined by the folding, then measures may be provided for compensating logical direction reversals of the boards.

Abstract: A modular printed circuit construction using visual or other representations (1 to 7) which can be arranged so as to produce a visual pattern in which continuous interconnections between the modules appear (automatically as a result of overlapping of individual representations). The composite visual pattern can be used to produce a unitary printed circuit board. Alternatively the individual printed circuit boards can be combined in a board assembly using a mounting frame or edge connectors. Two dimensional extension is possible. Particular applications include microprocessor systems (include parallel processors using a common memory). Bus lines can extend completely across individual representations or the unitary board. The positions of such lines can be determined in dependence on the number of individual representations to which they are common.