Method for detecting intermittent error in volatile memory

Patent 4698808 Issued on October 6, 1987. Estimated Expiration Date:

December 5, 2005. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.

Abstract Claims Description Full Text

Patent References

System for recovering data stored in failed memory unit
Patent #: 4092732
Issued on: 05/30/1978
Inventor: Ouchi

Device for testing programs for numerical control of machine tools
Patent #: 4354251
Issued on: 10/12/1982
Inventor: Hellwig , et al.

Electronic postage meter having redundant memory Patent #: 4566106
Issued on: 01/21/1986
Inventor: Check, Jr.

Inventor

Ishii, Takashi

Application

No. 06/806076 filed on 12/05/1985

US Classes:

714/722, Performing arithmetic function on memory contents714/54, Storage content error714/8Isolating failed storage location (e.g., sector remapping)

Examiners

Primary: Fleming, Michael R.

Attorney, Agent or Firm

International Classes

G06F 11/00 (20060101)
G06F 11/10 (20060101)
G11C 29/04 (20060101)
G11C 29/02 (20060101)
G11C 29/40 (20060101)
G11C 29/52 (20060101)

Foreign Application Priority Data

1984-12-14 JP

Abstract

Primary and secondary data save areas are established in a volatile memory (CMOS) which is backed up with a battery. The same predetermined data are stored in the primary and secondary data areas together with check sum. At a power on time, the data of the primary area are added together and the data of the secondary area are added together. When both of results of the addition are equal to the check sum, no error is detected. When only one of results of addition is different from the check sum, an intermittent error is detected. When both of results of addition are different from the check sum, battery exhausted condition is detected. If the intermittent error is detected, data of one area whose result of addition is equal to the check sum are copied to other area whose result addition is different from the check sum.