Digital Equipment Corporation

Compaq Computer Corporation, Inc.

Bradley James Benschneider

Victor Peng

A variable precedence priority encoder apparatus is provided having a plurality of inputs, each receiving a corresponding bit of an input vector, and a like plurality of outputs. Each output is associated with a corresponding one of the plurality of inputs, thereby forming a plurality of input/output pairs. The encoder circuit also includes a priority assignment circuit coupling each input of the plurality of inputs to its associated corresponding output of the plurality of outputs. The priority assignment circuit assigns a priority to each input/output pair, such that an output, which corresponds to an input which receives an asserted bit, and which has a highest priority, provides an asserted bit while all other outputs provide bits that are not asserted. The priority assigned to each input can be dynamically updated within the priority assignment circuit. Updates of priority that shift the priority position by one or more inputs can be done all using the same circuit. As such, the invention overcomes the limitations of the prior art by being reconfigurable into any precedence configuration using just a single encoder circuit.

Method and apparatus for a fast variable precedence priority encoder

In a multiplier unit implemented with carry/save adder stages and executing a modified Booth algorithm, the signals, required to complete the 2's complement in order to perform a subtraction operation during the multiplication procedure using carry/save adder cells, are entered in the first carry/save stage in the appropriate carry/save cell positions. In this manner, one less signal is processed by the time-critical least significant cell associated with each carry/save adder stage, thereby reducing the overall time delay associated with the multiplier unit and accelerating the multiplication operation.

Growing community of inventors

Lancaster, MA, United States of America

Bradley James Benschneider