The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
May. 21, 1991
Filed:
Jan. 02, 1990
Applicant:
Inventor:
Feng-Hsien W Shih, Yorktown Heights, NY (US);
Assignee:
IBM Corporation, , NY (US);
Attorney:
Primary Examiner:
Int. Cl.
CPC ...
G06F / ; G06F / ;
U.S. Cl.
CPC ...
364740 ; 364741 ; 364788 ;
Abstract
A carry select adder may be used in which carry inputs to ripple adder stages are not fixed. The adder stage determines which of the two ripple adders of that stage has output the correct sum while the variable carry input is equal to a given value. Then the variable carry input value is switched to a different value and the adder stage determines the correct output sum from the other ripple adder. The adder performs self-checking by comparing these two sums to ensure that the output sum is accurate.