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Self-examining device and method of ROM

A read-only memory and self-inspection technology, applied in static memory, instruments, etc., can solve the problem of leaking ROM content and achieve the effect of effective ROM self-inspection

Inactive Publication Date: 2009-02-25
VIMICRO CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] In view of this, the present invention needs to solve the problem that the content in the ROM may be leaked when carrying out the ROM self-inspection, so the purpose of the present invention is to provide a safer ROM self-inspection mode

Method used

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  • Self-examining device and method of ROM

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Embodiment Construction

[0022] The ROM self-testing device and method of the present invention will be described below in conjunction with the accompanying drawings. It is assumed that the content in the ROM should be A, but the actually stored content is B, and the present invention is used to detect whether the B is equal to A.

[0023] First introduce the Hash function, which is a one-way function, whose input can be of variable length, such as 128KB, 256KB, etc., and the output is of fixed length, such as 128bit. A prominent feature of the Hash function is that its output cannot be input, that is, it is a one-way function; another feature is that it is difficult to obtain the same specific output from two different inputs. At present, there are many kinds of Hash functions, such as SHA-1, MUD5, etc. In the following, if a certain Hash function is not specified, the function will be marked with f(x), where x is its input.

[0024] The present invention utilizes the two characteristics of the Hash...

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Abstract

A ROM selfcheck device is disclosed that includes: ROMBIST control module mounted in the chip, Hash function processing module, and reference value comparing module. The invention utilizes the characteristic of the Hash function, the value of ROM is sent to Hash function to process, the output of Hash function is transmitted to the outer face of chip and compare with reference value of Hash to realize the ROM selfcheck. Because of the characteristic of the Hash function, the value of ROM can't be got by conversion of the output of Hash function; the change of bit in ROM could result in the change of Hash function at the same time, so the effective ROM selfcheck can be realized without revealing the content of the ROM. It can be used for ROM selfcheck of various systems.

Description

technical field [0001] The invention relates to the detection field of memory, in particular to a self-detection device and method of a read-only memory. technical background [0002] ROM is read-only memory. ROM cannot be modified in the chip, and the value inside is preset during the chip design process. Because the ROM in the chip may have a fault due to manufacturing reasons, that is, the value B actually stored in the ROM may be different from the preset value A, which will cause the entire chip to function incorrectly. The chip submitted to the customer must be functionally correct, so it is generally necessary to perform a chip self-test on the ROM, that is, ROMBIST. A common practice is to set up a ROMBIST circuit in the chip, such as figure 1 As shown, during the self-test, the ROMBIST module reads the value B in the ROM and compares it with the reference value A preset in the comparison module outside the chip to determine whether A and B are equal. [0003] Sin...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G11C29/12
Inventor 杨柱
Owner VIMICRO CORP