Arithmetic and logic function circuits optimized for datapath layout

摘要

A technique for designing circuits with arithmetic or logic functions on integrated circuit devices. The circuit has a primary chain of serially connected logic blocks and secondary chains of serially connected logic blocks. The output node of the last logic block of each secondary chain is connected to an input node of a logic block in the primary chain. Depending upon the desired function, the logic blocks can be logic gates or more complex logic blocks. Zero detect and compare circuits can be designed from this basic arrangement. Connected with input logic, output logic and merge logic, other circuits, including incrementors, decrementors, priority logic, adders and ALUs, are possible. The resulting circuit occupies far less space on an integrated circuit than a fully parallel, lookahead circuit, yet operating speeds are comparable.