Abstract: A digital shifter/rotator for shifting an input word by an amount depending on a shift control word is described. The shifter/rotator comprises an array of FET pass transistors arranged in a sequential number of stages. The amount to be shifted in each stage is controlled by a corresponding shift control bit of the shift control word, whereby the output word of the rotator is the input word shifted by an amount equal to a sum of the number of shifts effected in each of the stages as determined by the shift control word. The rotator features selectable amount of shift in one machine cycle, high performance and reduced device count. Further improved performance is obtained by utilizing decoupling devices for isolating the input points of the stages, except when providing rotation, from the long rotation cross buses and its associated large parasitic capacitances.

Abstract: Complex logical mechanism, for simultaneously producing output signals related logically to a set of input signals, implemented in transfer gate pairs. The first transfer gate of each pair is connected generally in series and is controlled by conduction according to the signals applied. The second transfer gate of each pair shunts the output node of its related first transfer gate to ground, when enabled by a control signal complementary to the data pattern applied to the first transfer gate of the pair. This direct control of line voltages affirmatively drives the lines or affirmatively grounds the lines to eliminate back circuits.Carry propagation to higher order bit positions is along carry propagate lines, with series connected carry propagate first transfer gates. Order positions not having data values appropriate for carry propagation do not transmit carry values--these transfer gates are not controlled for conduction, but are nonetheless subject to possible back circuits.