Jeffery L Richardson

US Patent:

58727949, Feb 16, 1999

Filed:

Oct 29, 1997

Appl. No.:

8/967206

Inventors:

Brian E. Cook - Houston TX
Jeffery T. Richardson - Sugar Land TX
Yu-Ying Jackson Leung - Sugar Land TX

Assignee:

Texas Instruments Incorporated - Dallas TX

International Classification:

G01R 3128

US Classification:

371 224

Abstract:

Built-In-Logic-Block-Observation registers BILBO are coupled to the output of a Control-Read-Only-Memory CROM in the write-state-machine of a flash EPROM. The Built-In-Logic-Block-Observation registers BILBO include master/slave latches M/SL, shadow latches SHL, and other logic circuitry that enable the various modes of operation required for pulse timing and for signature analysis. During operation a pre-defined FLASH command sequence requests a Control-Read-Only-Memory CROM signature analysis that executes a set of instructions causing the Built-In-Logic-Block-Observation registers BILBO to be placed in the Multiple-Input-Signature-Register Mode and that steps through the Control-Read-Only-Memory CROM until all valid addresses have been evaluated. The resultant Control-Read-Only-Memory CROM signature is then scanned out and verified. The invention eliminates the need for a separate stand-alone Linear-Feedback-Shift-Register LFSR used for pulse timing.