1. An arrangement comprising a plurality of input storage locations for storing digital words, a plurality of output storage locations for storing digital words. control memory input path means for sequentially receiving connection words each defining one of said input storage locations and one of said output storage locations, control memory means for storing, for at most a predetermined duration, each of said connection words received by said control memory input path means, transfer means coupled to said control memory means and responsive to said connection words stored by said control memory means, for transferring digital words stored in ones of said input storage locations, to ones of said output storage locations as defined by those connection words and first enable gate means also coupled to said control memory means, for selectively transmitting ones of said connection words stored by said control memory means, to said control memory input path means for storage again by said control memory means.