Built-in self-test circuit and method for validating an associative data array

• US 6,351,789 B1
• Filed: 05/29/1998
• Issued: 02/26/2002
• Est. Priority Date: 05/29/1998
• Status: Expired due to Term

• Current Assignee: VIA-Cyrix, Inc.
• Original Assignee: VIA-Cyrix, Inc.
• Inventors: Green, Daniel W.
• Primary Examiner(s): Kim, Matthew
• Assistant Examiner(s): VITAL, PIERRE M
• Application Number:
  US09/086,866
• Time in Patent Office: 1,369 Days
• Field of Search: 711/114, 711/128, 714/21, 714/30, 714/36, 714/702, 714/718, 714/719, 714/720, 714/733, 714/736
• US Class Current: 711/128
• CPC Class Codes: G06F 12/0802 Addressing of a memory level in which the access to the desired data or data block requires associative addressing means, e.g. caches

Abstract

There is disclosed, for use in a processing device having an N-way set associative data array (such as an L1 cache), a built-in self-test (BIST) circuit for testing the validity of storage locations in the data array. The BIST circuit comprises 1) a memory capable of storing a test program executable by the processing device, wherein the test program is capable of testing the validity of the storage locations in the data array; and 2) a controller capable of copying the test program from the memory into first selected storage locations in a first way in the data array, wherein the processing device executes the copied test program stored in the first selected storage locations subsequent to the copying to thereby test the validity of second selected storage locations in at least one of the N ways.

Claims

1. A built-in self-test (BIST) circuit for testing the validity of storage locations in an N-way set associative data array of any processing device, comprising:

a memory capable of storing a test program executable by said processing device, wherein said test program and is capable of testing the validity of said storage locations in said data array; and

a controller capable of copying said test program from said memory into first selected storage locations in a first way in said data array, wherein said controller retrieves at least a portion of said copied test program from said first selected storage locations and compares said retrieved portion to a corresponding portion of said test program in said memory to determine if said retrieved portion and said corresponding portion are identical.

2. The BIST circuit set forth in claim 1 wherein if said retrieved portion and said corresponding portion are identical then said processing device executes said copied test program stored in said first selected storage locations to thereby test the validity of second selected storage locations in at least one of said N ways.

3. The BIST circuit set forth in claim 2 wherein said second selected storage locations and said first selected storage locations are disposed in different ways.

4. The BIST circuit set forth in claim 2 wherein said second selected storage locations and said first selected storage locations are disposed in the same way.

5. The BIST circuit set forth in claim 1 wherein said controller, in response to a determination that said retrieved portion and said corresponding portion are not identical, copies said test program from said memory into third selected storage locations in a second way in said data array.

6. The BIST circuit set forth in claim 5 wherein said controller retrieves at least a portion of said copied test program from said third selected storage locations and compares said retrieved portion to a corresponding portion of said test program in said memory to determine if said retrieved portion and said corresponding portion are identical.

7. The BIST circuit set forth in claim 5 wherein said processing device executes said copied test program stored in said third selected storage locations subsequent to said copying to thereby test the validity of second selected storage locations in at least one of said N ways.

8. The BIST circuit set forth in claim 1 wherein said memory is a read-only memory (ROM).

9. The BIST circuit set forth in claim 1 wherein said data array is a cache memory in said processing device.

10. A computer system having any processing device for executing instructions and processing data stored in a system memory, said processing device comprising:

an N-way set associative cache for storing portions of said data or ones of said instructions; and

a built-in self-test (BIST) circuit for testing the validity of storage locations in said cache, said BIST circuit comprising;

a memory capable of storing a test program executable by said processing device wherein said test program is capable of testing the validity of said storage locations in said cache; and

a controller capable of copying said test program from said memory into first selected storage locations in a first way in said cache, wherein said controller retrieves at least a portion of said copied test program from said first selected storage locations and compares said retrieved portion to a corresponding portion of said test program in said memory to determine if said retrieved portion and said corresponding portion are identical.

11. The computer system set forth in claim 10 wherein if said retrieved portion and said corresponding portion are identical said processor executes said copied test program stored in said first selected storage locations to thereby test the validity of second selected storage locations in at least one of said N ways.

12. The computer system set forth in claim 11 wherein said second selected storage locations and said first selected storage locations are disposed, in different ways.

13. The computer system set forth in claim 11 wherein said second selected storage locations and said first selected storage locations are disposed in the same way.

14. The computer system set forth in claim 10 wherein said controller, in response to a determination that said retrieved portion and said corresponding portion are not identical, copies said test program from said memory into third selected storage locations in a second way in said data array.

15. The computer system set forth in claim 14 wherein said controller retrieves at least a portion of said copied test program from said third selected storage locations and compares said retrieved portion to a corresponding portion of said test program in said memory to determine if said retrieved portion and said corresponding portion are identical.

16. The computer system set forth in claim 14 wherein said processing device executes said copied test program stored in said third selected storage locations subsequent to said copying to thereby test the validity of second selected storage locations in at least one of said N ways.

17. The computer system set forth in claim 10 wherein said memory is a read-only memory (ROM).

18. The computer system set forth in claim 10 wherein said data array is a cache memory in said processing device.

19. A method for testing the validity of storage locations in an N-way set associative data array of a processing device, comprising the steps of:

storing in a memory in the processing device a test program executable by the processing device, wherein the test program is capable of testing the validity of the storage locations in the data array;

copying the test program from the memory into first selected storage locations in a first way in the data array;

retrieving at least a portion of said copied test program from said first selected storage locations; and

comparing said retrieved portion to a corresponding portion of said test program in the memory to determine if said retrieved portion and said corresponding portion are identical.

20. The method set forth in claim 19 further comprising the step of executing the copied test program stored in the first selected storage locations if said retrieved portion and said corresponding portion are identical to thereby test the validity of second selected storage locations in at least one of the N ways.

21. The method set forth in claim 20 wherein the second selected storage locations and the first selected storage locations are disposed in difference ways.

22. The method set forth in claim 20 wherein the second selected storage locations and the first selected storage locations are disposed in the same way.