Abstract: A decoder having a plurality of outputs (R.sub.0 -Rn) each associated with a particular output valve is arranged to add together two binary numbers (A, B) and to select one of the outputs in dependence on the result of the sum. The decoder comprises a plurality of logic circuits each arranged to receive respective bits of both first and second binary numbers to be added together. The logic circuits are arranged to provide, for each output value, a respective result in dependence on the logic states of respective bits of binary numbers representing that particular output value of the decoder. The logic means determines when a predetermined condition is satisfied by the results of the logic circuits associated with an output value of the decoder, whereby that output value is selected.

Abstract: A line delay device comprises a memory having RAM cells in two blocks, each cell being connected to a pair of bit lines. Memory locations in one block are addressed sequentially and subject to a data transfer while an equate operation is effected on the bit lines of the other block. The operations are switched alternately between the two blocks. In each accessing cycle, a plurality of locations are addressed in selected rows of each block and the switching between each block is effected without addressing all locations in each row addressed so that the accessing cycle ends in a different block from the starting block and each row used has a plurality of addressed locations.