Browse Prior Art Database

Adaptive Data Update Method to Non Volatile Memory

IP.com Disclosure Number: IPCOM000016459D
Original Publication Date: 2000-Feb-01
Included in the Prior Art Database: 2003-Jun-23
Document File: 2 page(s) / 95K

Publishing Venue

IBM

Abstract

A program is disclosed that minimizes the amount of data lost from nonvolatile memory when a device is turned off, whether intentionally or accidentally. The method is to calculate the interval of accesses to nonvolatile memory from elapsed time and the amount of data that has been changed since the last time the nonvolatile memory was updated.

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Adaptive Data Update Method to Non Volatile Memory

A program is disclosed that minimizes the amount of data lost from nonvolatile memory
when a device is turned off, whether intentionally or accidentally. The method is to
calculate
the interval of accesses to nonvolatile memory from elapsed time and the amount of
data
that has been changed since the last time the nonvolatile memory was updated.

A device keeps data in RAM (random access memory) because RAM is accessible whenever
it is needed. In order to retain data after the power is turned off, the data in RAM
is copied
to nonvolatile memory because the number of write accesses to the nonvolatile memory
is
limited by the characteristics of the memory. The interval that the data in RAM is
copied
to nonvolatile memory is very important, because the average data lost in nonvolatile
memory
is strongly dependent on the interval. By the new method, the next update interval of
nonvolatile memory is determined from elapsed time and the total number of data
changes
made in RAM since the preceding update.

The evaluation function is defined as
V(t, d) = t + d ,

where t is the elapsed time since the preceding update
d is the number of data changes in RAM during that time
and are coefficients of each parameter
Data in RAM is copied to nonvolatile memory in accordance with the algorithm described
in the figure.

 Norm al EstiO perationmation

P hase

PO R

VTHttimer =

   Spent ttimer C hanged data in R A M V(t,d) = t + d

 Flash Memory

Update

V(t,d) < VTH

ttimer = VTH - V (t,d)

0 = d 0,t =V(t,d) m VTH

Vttimer =TH

If V(t, d) exceeds a threshold value VTH , the data in RA...