Non-volatile memory, memory card and information processing apparatus using the same and method for software write protect control of non-volatile memory

• US 6,032,237 A
• Filed: 06/19/1998
• Issued: 02/29/2000
• Est. Priority Date: 08/03/1994
• Status: Expired due to Term

• Current Assignee: Emergence Memory Solutions LLC
• Original Assignee: Hitachi, Ltd., Hitachi ULSI Engineering Corp, Hitachi Tohbu Semiconductor, Ltd. (Renesas Electronics Corporation)
• Inventors: Suzuki, Shigeru, Inoue, Manabu, Iwasaki, Hironori, Kubota, Yasuro, Nakanishi, Satoru, Okubo, Takao, Kadowaki, Shigeru, Kishi, Masamichi
• Primary Examiner(s): Chan, Eddie
• Assistant Examiner(s): Portka, Gary J.
• Application Number:
  US09/100,326
• Time in Patent Office: 620 Days
• Field of Search: 711/103, 711/152, 711/163, 365/185.11, 365/185.29, 365/185.33, 365/195, 365/218
• US Class Current: 711/163
• CPC Class Codes: G06F 12/1441 for a range
• CPC Class Codes: G11C 16/22 Safety or protection circuits preventing unauthorised or accidental access to memory cells
• CPC Class Codes: G11C 8/20 Address safety or protection circuits, i.e. arrangements for preventing unauthorized or accidental access

Abstract

A non-volatile memory, such as a flash memory card, using a rewritable non-volatile memory is provided with an improved write-protect arrangement. The non-volatile memory includes a collectively electrically erasable and writable memory (e.g., a flash memory), a reset IC for generating a power-on reset signal upon turn-on of the power supply, and a card controller for performing control between each flash memory device and a memory card interface. The flash memory is set with a write protect save register written with an address of an area desired to be subjected to write protect, the write protect save register belonging to an attribute area, and a protect range is set from the system. Since the address to be write-protected is itself written in the non-volatile flash memory, the address will continue to be stored, even if the power is turned off. A method for software write protection control is also provided.

Claims

1. A non-volatile memory card comprising:

a rewritable non-volatile memory including;

a data storage area, and

a write protect information save area which stores write protect information representing a write protect area of the data storage area;

a volatile register into which the write protect information is set from the write protect information save area in response to a reset operation; and

a judgment circuit which receives an input address signal and the write protect information stored in the volatile register and which judges whether an address of an accessed location of the rewritable non-volatile memory by the input address signal is in the write protect area, and which inhibits a write operation based on the input address signal when the address of the accessed location of the rewritable non-volatile memory indicated by the input address signal is in the write protect area.

2. A non-volatile memory card according to claim 1, wherein the volatile register and the judgment circuit are included in a card controller.

3. A non-volatile memory card according to claim 1, wherein the write protect information save area is located at an attribute area of the address space of the rewritable non-volatile memory.

4. A non-volatile memory card according to claim 1,

wherein a memory space of the rewritable non-volatile memory is divided into sector units, and

wherein the write protect information represents one or more sectors in the data storage area as the write protect area.

5. A non-volatile memory card according to claim 4, wherein the write protect information save area is located at the final sector in the memory space of the rewritable non-volatile memory.

6. A non-volatile memory card according to claim 1, wherein the reset operation is one of a power-on reset operation, a hardware reset operation and a software reset operation.

7. A non-volatile memory card according to claim 1,

wherein the write protect information save area is located at an attribute area of the address space of the rewritable non-volatile memory,

wherein the volatile register and the judgment circuit are included in a card controller, and

wherein the write protect information is transferred to said volatile register from said write protect information save area in response to a control signal for selecting the attribute area.

8. A non-volatile memory card according to claim 2, wherein each of memory cells included to said rewritable non-volatile memory has a floating gate.

9. A non-volatile memory card according to claim 3, wherein each of memory cells included to said rewritable non-volatile memory has a floating gate.

10. A non-volatile memory card according to claim 5, wherein each of memory cells included to said rewritable non-volatile memory has a floating gate.

11. A non-volatile memory card according to claim 8, wherein each of memory cells included to said rewritable non-volatile memory has a floating gate.

12. A non-volatile memory card according to claim 7, wherein each of memory cells included to said rewritable non-volatile memory has a floating gate.

13. A memory card comprising:

an electrically erasable and rewritable non-volatile memory including;

a data storage area, and

an attribute area at which write protect information defining addresses representing a write protect area of the data storage area is stored; and

a card controller including;

a volatile register into which the write protect information is set from the attribute area; and

a judgment circuit which receives an input address signal and the write protect information stored in the volatile register and which judges whether an address of an accessed location of the rewritable non-volatile memory by the input address signal is in the write protect area so as to prevent a write operation based on the input address signal when the address of the accessed location of the rewritable non-volatile memory by the input address signal is in the write protect area,

wherein the card controller controls to transfer the write protect information to said volatile register from said write protect information save area in response to a control signal for selecting the attribute area.

14. A memory card according to claim 13, wherein each of memory cells included to said electrically erasable and rewritable non-volatile memory has a floating gate.

15. A memory card comprising:

an electrically erasable and rewritable non-volatile memory including;

a data storage area, and

an area at which write protect information defining addresses representing a write protect area of the data storage area is stored, and

a card controller including;

a reset control circuit responsive to a reset operation and generating first to third transfer control signals,

an address controller responsive to the first transfer control signal and generating an address signal for accessing the area to the electrically erasable and rewritable non-volatile memory, and

a control signal generating circuit responsive to the second transfer control signal and generating an output enable signal and a chip select signal to the electrically erasable and rewritable non-volatile memory, so that the write protect information stored in the area of the electrically erasable and rewritable non-volatile memory is read out,

a volatile register responsive to the third transfer control signal and latching the write protect information read out from the electrically erasable and rewritable non-volatile memory therein; and

a judgment circuit which receives an input address signal and the write protect information stored in the volatile register and which judges whether an address of an accessed location of the rewritable non-volatile memory by the input address signal is in the write protect area so as to prevent a write operation based on the input address signal when the address of the accessed location of the rewritable non-volatile memory by the input address signal is in the write protect area.

16. A memory card according to claim 15, wherein the area is located at an attribute area of the address space of the electrically erasable and rewritable non-volatile memory.

17. A memory card according to claim 15,

wherein a memory space of the electrically erasable and rewritable non-volatile memory is divided into sector units, and

wherein the write protect information represents one or more sectors in the data storage area as the write protect area.

18. A memory card according to claim 17, wherein the area is located at the final sector in the memory space of the electrically erasable and rewritable non-volatile memory.

19. A memory card according to claim 15, wherein the reset operation is one of a power-on reset operation, a hardware reset operation and a software reset operation.

20. A memory card according to claim 15,

wherein the write protect area is located at an attribute area of the address space of the rewritable non-volatile memory, and

wherein the card controller is responsive to a control signal for selecting the attribute area and accesses the attribute area to rewrite the write protect information with new write protect information, thereby setting a desired write protection area.

21. A memory card according to claim 15,

wherein the write protect information includes start and end address data for the write protect area, and

wherein the volatile register includes:

a first register for storing the start address data for the write protect area, and

a second register for storing the end address data for the write protect area.

22. A memory card according to claim 16, wherein each of memory cells included to said rewritable non-volatile memory has a floating gate.

23. A memory card according to claim 18, wherein each of memory cells included to said rewritable non-volatile memory has a floating gate.

24. A memory card according to claim 19, wherein each of memory cells included to said rewritable non-volatile memory has a floating gate.

25. A memory card according to claim 20, wherein each of memory cells included to said rewritable non-volatile memory has a floating gate.

26. A memory card according to claim 21, wherein each of memory cells included to said rewritable non-volatile memory has a floating gate.