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:
Oct. 21, 1986
Filed:
Jan. 09, 1984
Anthony G Aipperspach, Rochester, MN (US);
Joseph M Fitzgerald, Rochester, MN (US);
Philip T Wu, Rochester, MN (US);
International Business Machines Corporation, Armonk, NY (US);
Abstract
A combined read-only and static read/write semiconductor memory is achieved by modifying the normal threshold voltage of some of the transfer FETs in an otherwise conventional static-memory cell. A read/write data bit is recovered from an addressed cell by applying a word-line voltage higher than both the threshold voltages. Read-only data is read from the same addressed cell by using a word-line voltage higher than one of the thresholds but lower than the other, then decoding the resulting bit-line voltages. An extension allows multiple read-only bits in a single cell by lowering the cell supply voltage when read-only data are addressed.