METHOD AND SYSTEM FOR UPDATING A STORED DATA VALUE IN A NON-VOLATILE MEMORY

• US 20090091977A1
• Filed: 06/03/2008
• Published: 04/09/2009
• Est. Priority Date: 10/04/2007
• Status: Active Grant

• Current Assignee: Arc Innovations Limited
• Original Assignee: Arc Innovations Limited
• Inventors: Hunt, Stephen Gregory
• Granted Patent: US 7,813,176 B2
• Time in Patent Office: Days
• US Class Current: 365/185.08
• CPC Class Codes: G11C 13/0069 Writing or programming circuits or methods
• CPC Class Codes: G11C 14/00 Digital stores characterised by arrangements of cells having volatile and non-volatile storage properties for back-up when the power is down
• CPC Class Codes: G11C 16/102 External programming circuits, e.g. EPROM programmers; In-circuit programming or reprogramming; EPROM emulators
• CPC Class Codes: G11C 2013/0076 Write operation performed depending on read result

Abstract

The invention provides a method of updating a stored data value in a non-volatile memory. The method includes reading the stored data value from the non-volatile memory; reading a stored differential value from a volatile memory; receiving an updated data value; calculating a calculated differential value from the difference between the updated data value and the sum of the stored data value and the stored differential value; comparing the calculated differential value with a threshold differential value; and writing the updated data value to the non-volatile memory if the calculated differential value exceeds the threshold differential value. The invention further provides a related memory system.

Claims

1. A method of updating a stored data value in a non-volatile memory, the method comprising:

reading the stored data value from the non-volatile memory;

reading a stored differential value from a volatile memory;

receiving an updated data value;

calculating a calculated differential value from the difference between the updated data value and the sum of the stored data value and the stored differential value;

comparing the calculated differential value with a threshold differential value; and

writing the updated data value to the non-volatile memory if the calculated differential value exceeds the threshold differential value.

2. The method of claim 1 further comprising writing the calculated differential value to volatile memory if the calculated differential value is less than the threshold differential value.

3. The method of claim 2 further comprising:

reading one or more previously calculated differential values from the volatile memory prior to power interruption to the volatile memory; and

writing the previously calculated differential values to the non-volatile memory.

4. The method of claim 2 further comprising:

reading one or more previously calculated differential values from the volatile memory prior to power interruption to the volatile memory; and

writing the previously calculated differential values to a further non-volatile memory.

5. The method of claim 1 further comprising writing a value of zero for the stored differential value on the volatile memory if the calculated differential value exceeds the threshold differential value.

6. A memory system comprising:

a non-volatile memory in which is maintained a plurality of stored data values;

a volatile memory in which is maintained a plurality of differential values;

an input device configured to receive an updated data value;

an I/O device configured to retrieve one of the stored data values from the non-violate memory and to retrieve one of the differential values from the volatile memory;

a calculating component configured to calculate a calculated differential value from the difference between the updated data value and the sum of the retrieved stored data value and the retrieved differential value; and

a comparator configured to compare the calculated differential value with a threshold differential value;

the I/O device configured to write the updated data value to the non-volatile memory if the calculated differential value exceeds the threshold differential value.