Methods and apparatus for efficiently managing flash memory

• US 5,912,848 A
• Filed: 09/26/1997
• Issued: 06/15/1999
• Est. Priority Date: 09/30/1996
• Status: Expired due to Term

• Current Assignee: RPX Corporation
• Original Assignee: Nokia Mobile Phones UK Limited (Nokia Corporation)
• Inventors: Bothwell, Leslie Innes
• Primary Examiner(s): Nelms, David
• Assistant Examiner(s): NGUYEN, HIEN N
• Application Number:
  US08/938,494
• Time in Patent Office: 627 Days
• Field of Search: 365/195, 365/185.33, 365/185.29, 365/185.3
• US Class Current: 365/195
• CPC Class Codes: G06F 12/0246 in block erasable memory, e.g. flash memory
• CPC Class Codes: H04M 1/724 User interfaces specially adapted for cordless or mobile telephones

Abstract

An electronic device, such as a radio telephone, includes a non-volatile memory, such as a Flash memory, for storing data and instructions, a non-volatile memory, typically a RAM, for storing data and instructions, and a controller. The data stored in the RAM includes data intended for storage in the Flash memory. The controller controls memory management operations of the radio telephone and is responsive to an occurrence of an interrupt during one of a Flash memory write operation or a Flash memory erase operation for selectively one servicing the interrupt or delaying servicing the interrupt. The controller is further responsive to priorities of data stored in the RAM, as well as to an amount of stored data for predetermined priorities, for scheduling a Flash memory write operation for transferring stored data from said RAM to said Flash memory.

Claims

1. A memory management method, comprising the steps of:

executing instructions in non-volatile memory until a modification command to modify non-volatile memory is received;

on receipt of the modification command to modify non-volatile memory, commencing an execution of instructions in a volatile memory and a modification operation in the-non-volatile memory;

on receipt of an interrupt signal, determining whether the non-volatile memory is undergoing a modification operation and, if so, suspending the modification operation and servicing the interrupt signal;

once the interrupt signal has been serviced, resuming the non-volatile memory modification operation; and

once the modification operation is completed, re-commencing the execution of instructions in the non-volatile memory.

2. A method according to claim 1, wherein the modification command specifies a write command, and on receipt of a write command, the method further comprises a step of determining a duration for the writing of an electronic signal to the non-volatile memory.

3. A method according to claim 2, further comprising a step of delaying servicing the interrupt for the determined duration of the writing if the duration is less than a predetermined time period.

4. A method according to claim 2, further comprising steps of:

determining when a pause exists during the writing,

delaying servicing the interrupt for the occurrence of the pause,

inhibiting the writing during the pause, and

servicing the interrupt while the writing is inhibited.

5. A method according to claim 4, wherein the writing comprises writing a plurality of data representing first and second groups of electronic signals, and wherein the pause occurs between writing the first group and writing the second group.

6. A method according to claim 5, wherein the groups of electronic signals are representative of digital words.

7. A method according to claim 1, wherein the modification command specifies an erase command, and during an erase operation of the non-volatile memory means, the method further comprises a step of inhibiting the erase operation and servicing the interrupt signal during the time that the erase operation is inhibited.

8. Electronic apparatus, comprising:

volatile memory means, non-volatile memory means and control circuitry,

wherein the control circuitry causes instructions to be executed in the non-volatile memory means until a modify command is received to perform a modification operation on said non-volatile memory means;

on receipt of a modify command, said control circuitry causes an execution of instructions in said volatile memory means and an execution of the modify command;

on receipt of an interrupt signal, said control circuitry determines whether said non-volatile memory means is undergoing a modification operation and, if so, suspends the modification operation and services the interrupt signal;

once the interrupt signal has been serviced, said control circuitry causes resumption of the modification operation of the non-volatile memory means; and

once the modification is complete, the control circuitry causes re-commencement of the execution of the instructions in said non-volatile memory means.

9. Electronic apparatus as in claim 8, wherein said electronic apparatus is comprised of a radio telephone, and wherein said modify command specifies that a write operation be performed in said non-volatile memory means.

10. Electronic apparatus as in claim 8, wherein said electronic apparatus is comprised of a radio telephone, and wherein said modify command specifies that an erase operation be performed in said non-volatile memory means.