Patent EP0283238A2 successfully refreshed from Google Patents.
EP0283238A2
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EP
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Non-volatile memory
Assignee: Hitachi Ltd
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Filing: 1988-03-15
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Granted: —
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Expires: 2008-03-15
Abstract
Abstract A means (35) for latching stored data is disposed outside an array of non-volatile memory cells (1). Before erasure of the memory cells (1), some of the stored data items in the non-volatile memory cells are transferred to and held in the latch means (35). The saved data items are written again after erasure, or alternatively, the data items transferred to the latch means (35) are used to determine certain designated regions in which erasure is inhibited. This enables the conservation of certain stored items, and thus, the prevention of illicit use. The shortening of testing time is also made compatible with the conservation.
Inventors
- 👤 Naoki Mitsuishi
- 👤 Yoh No. 103 Dainifujikohpo Takamori
- 👤 Kiyoshi Matsubara
- 👤 Yoshiyuki Ozawa
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-07 12:46
CPC Classifications
G; G11; G11C; G11C17/00; G11C16/00; G11C16/02; G11C16/06; G11C16/10; G11C16/14; G11C16/16; G06; G06F; G06F12/00; G06F12/14; G06F12/1416; G06F12/1425; G06F12/1433; G11C16/22; G11C16/26
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
58 words
A non-volatile memory comprising an array of non-volatile memory cells (1), and means (36) adapted to electrically write and erase data into and from the group (1) of non-volatile memory cells, characterised in that the means (36) enables the conservation of the contents of at least one rank of memory cells during erasure of the other memory cells.
Claim 2
Dependent Claim
58 words
A non-volatile memory comprising an array of non-volatile memory cells (1), and means (36) adapted to electrically write and erase data into and from the group (1) of non-volatile memory cells, characterised in that the means (36) enables the conservation of the contents of at least one rank of memory cells during erasure of the other memory cells.
Claim 3
Dependent Claim
33 words
A non-volatile memory according to claim 1, having an address decoder (31), wherein the means for electrically writing and erasing data is a control circuit (36) connected directly to the address decoder (31).
Claim 4
Dependent Claim
92 words
A non-volatile memory according to claim 2, having a volatile storage means (35) separate from the group (1) of non-volatile memory cells, and the control circuit (36) operates to effect the transfer of the contents of at least one rank of memory cells within the group (1) of non-volatile memory cells to the volatile storage means before erasure of all the non-volatile memory cells and thereafter to effect the writing of the contents of the at least one rank into its original memory cell rank of the group of non-volatile memory cells.
Claim 5
Dependent Claim
42 words
.4. A non-volatile memory according to claim 2 or claim 3, wherein the volatile storage means (35) also serves as a latch means for holding stored data items of a non-volatile memory cell rank at a designated address in a read mode.
Claim 6
Dependent Claim
64 words
A non-volatile memory according to any of claims 2 to 4, wherein the address decoder (31) for selecting a specified rank within the group of non-volatile memory cells operates in the erase mode to first form a signal for selecting a predetermined rank, to subsequently form a signal for selecting all ranks, and to thereafter form a signal for selecting the predetermined rank again.
Claim 7
Dependent Claim
42 words
A non-volatile memory according to claim 2, wherein some of the contents of the volatile storage means held in the erase mode are used for designating whether or not the saved contents are to be rewritten into the original memory cell rank.
Claim 8
Dependent Claim
38 words
A non-volatile memory according to claim 1, claim 2, claim 4 or claim 5, wherein protected information contained in at least one predetermined memory cell rank is used to determine which memory cell ranks are to be erased.
Claim 9
Dependent Claim
14 words
A microcomputer comprising a built-in non-volatile memory according to any of the preceding claims.
Claim 10
Dependent Claim
40 words
A microcomputer according to claim 8, having a first path for accessing the group of non-volatile memory cells directly from outside the microcomputer and a second separate path for access to the group of non-volatile memory cells by the microprocessor.
Claim 11
Dependent Claim
53 words
A microcomputer according to claim 9, comprising mode setting means for determining an operation mode on the basis of a specified control signal applied from outside said microcomputer, said mode setting means being adapted to deliver a control signal for validating either of the first or second access paths to said non-volatile memory.
Claim 12
Dependent Claim
28 words
A microcomputer according to claim 9, wherein the cells of said group of non-volatile memory cells can be erased only through the first path to said non-volatile memory.
Claim 13
Dependent Claim
26 words
A microcomputer according to claim 9, wherein the cells of said group of non-volatile memory cells can be erased through either the first or second paths.
Claim 14
Dependent Claim
54 words
A microcomputer according to claim 8, wherein the microcomputer is a single-chip microcomputer in which a microprocessor, a read only memory for storing programs, a volatile random access memory, and communication means for sending and receiving data to and from an external equipment are packaged on a semiconductor chip together with the non-volatile memory.
Claim 15
Independent Claim
60 words
A method of operating a non-volatile memory containing secret or protected information comprising the steps of: reading at least the part of the non-volatile memory containing the protected or secret information; storing the information read from the non-volatile memory in a volatile storage means; and erasing at least those parts of the memory not containing the secret or protected information.
Claim 16
Independent Claim
60 words
A method of operating a non-volatile memory containing secret or protected information comprising the steps of: reading at least the part of the non-volatile memory containing the protected or secret information; storing the information read from the non-volatile memory in a volatile storage means; and erasing at least those parts of the memory not containing the secret or protected information.
Claim 17
Dependent Claim
43 words
A method of operating a non-volatile memory according to claim 14, wherein the whole of the contents of the non-volatile memory are erased and further comprising the steps of: rewriting the contents of the volatile storage means in the non-volatile memory after erasure.
Claim 18
Dependent Claim
31 words
A method of operating a non-volatile memory according to claim 14 wherein the contents of the volatile storage means is used to determine which parts of the non-volatile memory are erased.
References Cited (Backward Citations)
No citation records indexed.
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