Abstract: Multistage digital signal multiplying and adding apparatus suitable for a multistage filter includes a plurality of addition stages each having adding devices for forming a succession of partial products together with selectors operable in a first condition to connect sum and carry outputs of the adding devices within a stage to further adding devices within the stage or a second condition to supply outputs to a further stage, the selectors being operable to change condition without resolving carry signals in one stage through all bit positions of that stage. The output of one stage is connected to a subsequent stage during a first cycle of product formation of the subsequent stage so that the output is accumulated with the first partial product of the subsequent stage.

Abstract: A cascaded array of devices, each having electrical signal processing elements arranged to process simultaneously the same input data, is provided with inter-device connections including signal delay so that an intermediate result of processing by a second device is combined with an output which was derived from a first device at a time related to that at which input data was input to the second device for use in forming its intermediate result.