Dismiss
InnovationQ will be updated on Sunday, Oct. 22, from 10am ET - noon. You may experience brief service interruptions during that time.
Browse Prior Art Database

Droppable Function ALU

IP.com Disclosure Number: IPCOM000040952D
Original Publication Date: 1987-Apr-01
Included in the Prior Art Database: 2005-Feb-02
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Kouba, DJ: AUTHOR

Abstract

Modern design automation systems generally include a library of standardized mask images for complex logical functions which are composed of component images of more elementary logic functions. When the designer wishes to assemble several complex logic functions in designing a mask image for a large scale integrated circuit chip, the designer will select from the library those complex logic function images he desires and will instruct the design automation system to interconnect the functions in the circuit topology he desires. Frequently, the standardized image of the complex logic function includes more elementary functions than the designer may need for a particular application.

This text was extracted from a PDF file.
This is the abbreviated version, containing approximately 57% of the total text.

Page 1 of 1

Droppable Function ALU

Modern design automation systems generally include a library of standardized mask images for complex logical functions which are composed of component images of more elementary logic functions. When the designer wishes to assemble several complex logic functions in designing a mask image for a large scale integrated circuit chip, the designer will select from the library those complex logic function images he desires and will instruct the design automation system to interconnect the functions in the circuit topology he desires. Frequently, the standardized image of the complex logic function includes more elementary functions than the designer may need for a particular application. Since the component elementary logic functions which are not used in the complex logic function may add extra capacitance or signal propagation delay to the characteristics of the overall performance of the complex logic function, it would be beneficial to the designer to be able to selectively eliminate some of the unused elementary logic functions in the standardized image. This is achieved by the invention disclosed herein.

The figure shows a schematic diagram of an arithmetic logic unit (ALU) macro which represents a complex logic function having five more elementary logic functions F1 through F5, as component logic functions. Each respective elementary logic function F1 through F5 has a corresponding input terminal I1 through I5, respectively, and a correspo...