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. 12, 1987
Filed:
Jan. 03, 1983
James H Cline, Allen, TX (US);
David M Chastain, Plano, TX (US);
Texas Instruments Incorporated, Dallas, TX (US);
Abstract
A memory apparatus including an array of storage elements connected to a plurality of addressing lines for selectively connecting a group of the storage elements to a plurality of data lines. Protection circuitry is provided that is connected to the address lines for storing flags corresponding to selected groups of the storage elements to be protected. Write circuitry is provided that is connected to the address lines and to the array of storage elements for preventing the writing into the storage elements addressed by the address lines when the address is within the address of the protected groups. Control circuitry is provided that is connected to the protect circuit and the write circuit for controlling the input of the protect group addresses and for enabling the write circuit means during a write operation. The memory apparatus further includes the capability to provide protection from writing from a direct memory access source or from a central processing unit source. The control circuit in the memory system is provided with an override capability to override the write protection circuits.