Method of overwriting data in nonvolatile memory and a control apparatus used for the method

• US 20020199054A1
• Filed: 05/20/2002
• Published: 12/26/2002
• Est. Priority Date: 05/22/2001
• Status: Active Grant

• Current Assignee: Digital Cache, LLC (Oso IP, LLC)
• Original Assignee: Sankyo Seiki Manufacturing Co., Ltd. (Nidec Corporation)
• Inventors: Akahane, Fumihiko, Baba, Tsutomu
• Granted Patent: US 6,851,015 B2
• Time in Patent Office: Days
• US Class Current: 711/103
• CPC Class Codes: G11C 16/102 External programming circuits, e.g. EPROM programmers; In-circuit programming or reprogramming; EPROM emulators
• CPC Class Codes: G11C 16/105 Circuits or methods for updating contents of nonvolatile memory, especially with 'security' features to ensure reliable replacement, i.e. preventing that old data is lost before new data is reliably written

Abstract

A method of overwriting nonvolatile memory data in which data of interest is stored sector by sector comprises, when overwriting data of interest, the steps of providing a backup region having at least the same memory capacity as the sector to which data to be overwritten belongs, pre-overwriting data in the sector to which data to be overwritten belongs is first written in the backup region, then, erasing data to be overwritten pre-overwrite from the sector and then post-overwriting data written in the sector together with an error detection code for the post-overwrite data.

Claims

1. A method of overwriting nonvolatile memory data in which data of interest is stored sector by sector, comprising, when overwriting data of interest, the steps of:

providing a backup region having at least the same memory capacity as said sector to which data to be overwritten belongs;

pre-overwriting data in said sector to which data to be overwritten belongs is first written in said backup region;

then, erasing data to be overwritten pre-overwrite from said sector; and

then, post-overwriting data written in said sector together with an error detection code for said post-overwrite data.

2. The method of overwriting data in nonvolatile memory as set forth in claim 1 wherein, when said pre-overwrite data is written in said backup region, a pre-overwriting data error detection code is written in said backup region.

3. The method of overwriting data in nonvolatile memory as set forth in claim 1 wherein said backup region is a backup sector provided in said nonvolatile memory having the same memory capacity as said sector to which said data of interest belongs.

4. The method of overwriting data in nonvolatile memory as set forth in claim 1 wherein said nonvolatile memory is flash memory.

5. The method of overwriting nonvolatile memory data in which data of interest is stored sector by sector, comprising, when overwriting data of interest, the steps of:

providing a nonvolatile memory control apparatus for a backup region having at least the same memory capacity as said sector to which data to be overwritten belongs;

first writing data in the sector to which data to be overwritten belongs in said backup region;

then, erasing said data to be overwritten from said sector; and

then post-overwriting data written in said sector together with an error detection code for said post-overwrite data.