Browse Prior Art Database

NONVOLATILE MEMORY ARCHITECTURE USING FLASH MEMORY INSTEAD OF BATTERY BACKED RAM

IP.com Disclosure Number: IPCOM000027438D
Original Publication Date: 1996-Dec-31
Included in the Prior Art Database: 2004-Apr-07
Document File: 6 page(s) / 215K

Publishing Venue

Xerox Disclosure Journal

Abstract

Disclosed is an apparatus that bi-directionally transfers bytes of memory between volatile and nonvolatile storage allocations using a RAM (Random Access Memory) architecture and a Flash Memory. One skilled in the art will recognize that Flash Memory is a type of nonvolatile memory similar in function to EEPROM (Electrically Erasable Programmable Read Only Memory). However, Flash Memory must be erased in blocks, whereas EEPROM can be erased one byte at a time.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 45% of the total text.

Page 1 of 6

XEROX DISCLOSURE JOURNAL

NONVOLATILE MEMORY ARCHITECTURE Proposed Classification USING FLASH MEMORY INSTEAD OF
BATTERY BACKED RAM
Eric S. Redleaf
Laura Fichter

U. S. C1. 3651094 Int. C1. GI lc 17/00

II

      I-- ----- -- -- I 644 I

FIG. 1

XEROX DISCLOSURE JOURNAL - Vol. 21, No. 6 NovembedDecember 1996 387

[This page contains 1 picture or other non-text object]

Page 2 of 6

NONVOLATILE MEMORY ARCHITECTURE USING FLASH MEMORY INSTEAD OF BATTERY BACKED RAM (CONT'D)

+

 I NIT1 ALlZE NVM START

INlTlALlZE

NVM END

90

t

SAVE VALUE t READ FLASH (I + NVM STORAGE OFFSET)

I -

WRITE RAM (I, SAVE VALUE)

*

L 92

FIG. 2

3 88 XEROX DISCLOSURE JOURNAL - Vol. 21, No. 6 NovembedDecember 1996

[This page contains 1 picture or other non-text object]

Page 3 of 6

-

194

NONVOLATILE MEMORY ARCHITECTURE USING FLASH MEMORY INSTEAD OF BATTERY BACKED RAM (CONT'D)

START

PROCESS

INTERRUPT

DOWN BATTERY CIRCUIT

ERASE NVM BLOCK OF FLASH MEMORY

DO I FROM

NVM END

,

I

loo

f

102

t 1

OFF TURN SAVE VALUE t READ RAM (I)

POWER

BATTERY CIRCUIT

WRITE FLASH (I + NVM STORAGE OFFSET, SAVE VALUE)

FIG. 3

XEROX DISCLOSURE JOURNAL - Vol. 21, No. 6 NovemberDecember 1996 3 89

[This page contains 1 picture or other non-text object]

Page 4 of 6

NONVOLATILE MEMORY ARCHITECTURE USING FLASH MEMORY INSTEAD OF BATTERY BACKED RAM (CONT'D)

Disclosed is an apparatus that bi-directionally transfers bytes of memory between volatile and nonvolatile storage allocations using a RAM (Random Access Memory) architecture and a Flash Memory. One skilled in the art will recognize that Flash Memory is a type of nonvolatile memory similar in function to EEPROM (Electrically Erasable Programmable Read Only Memory). However, Flash Memory must be erased in blocks, whereas EEPROM can be erased one byte at a time.

Currently NVM (Nonvolatile Memory) requirements for most designs represent a small portion of the total RAM storage allocation. Flash Memory is becoming popular because it is easy to program and erase. In traditional NVM applications a battery is used to maintain the integrity of data stored in RAM during the absence of power. The disclosed architecture uses battery power to allow a NVM device to operate long enough to transfer RAM data to the Flash Memory. Once the transfer is complete a processor isolates the battery so no additional power is drained therefrom.

A Lithium battery has an expected lifetime of approximately 5 years assuming that the drain on the battery is idle for about 16 hours a day (typical for office equipment). The disclosed apparatus consumes approximately 13 seconds of battery life each time it is turned on and off. A Flash Memory can be programmed at least 10,000 times and can reliably sustain being programmed approximately 100,000 times. Assuming the disclosed architecture is powered on and off once a day, 365 days a year, the Flash Memory is capable of functioning as a NVM for 27.4 to 274 years.

Figure 1 schematically represents a preferred embodiment of the disclosed apparatus. Componen...