EP0154252A2
Expired / Lapsed
EP
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Programmable read only memory device and memory system employing the same
Assignee: Fujitsu Ltd
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Filing: 1985-02-20
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Granted: —
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Expires: 2005-02-20
Abstract
Abstract A memory system having an erasable programmable read only memory (EPROM) (52) for storing principal data. A read only memory (ROM) (71) for storing key data, and a processing unit (2) for writing or reading the principal data into or from the EPROM (52) applying the key data. The EPROM (52) has an address converter (504) having a volatile memory (5042,5045) for storing tentatively the key data. External address data for writing the principal data into the EPROM (52) are converted to internal address data by the address converter (504) using the key data stored in the volatile memory (5042,5045), so that the principal data stored in the EPROM (52) are read out by converting the external address data into the internal address data using the key data stored in the volatile memory (5042,5045). The key data stored in the ROM (71) are read out and applied to the volatile memory (5042, 5045) during the power of the memory system is ON, the control of the key data ist processed by processing unit (2).
Inventors
- 👤 Masanobu Yoshida
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-04 08:51
CPC Classifications
G; G06; G06F; G06F13/00; G06F13/14; G06F13/16; G06F12/00; G06F12/14; G06F12/1408
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
94 words
A programmable read only memory device for storing principal data receiving external address data and key data, characterized in a plurality of address input terminals XTO,T1...T(n-1) for receiving said external address data; a plurality of non-volatile memory cells (501) for storing said principal data; volatile memory means (5042,5045) for storing said key data; address converting means (504') for converting said external address data into internal address data according to said key data stored in said volatile memory means (5042,5045); and means (502) for accessing said non-volatile memory cells designated by said internal address data.
Claim 2
Dependent Claim
94 words
A programmable read only memory device for storing principal data receiving external address data and key data, characterized in a plurality of address input terminals XTO,T1...T(n-1) for receiving said external address data; a plurality of non-volatile memory cells (501) for storing said principal data; volatile memory means (5042,5045) for storing said key data; address converting means (504') for converting said external address data into internal address data according to said key data stored in said volatile memory means (5042,5045); and means (502) for accessing said non-volatile memory cells designated by said internal address data.
Claim 3
Dependent Claim
43 words
A programmable read only memory device according to claim 1 characterized in transfer gate means (5041, 5043) controlled by a control signal (Ø), said transfer gate means (5041,5044) transferring said key data applied to said address input terminals to said volatile memory means.
Claim 4
Dependent Claim
28 words
A programmable read only memory device according to claim 1 or 2, characterized in that said address converting means (1504) comprises a plurality of logical gate circuits (5043).
Claim 5
Dependent Claim
27 words
A programmable read only memory device according to claim 3 characterized in that said logical gate circuits (5043) comprises a plurality of exclusive OR gates (GO,G1 ....G(n-1).
Claim 6
Dependent Claim
31 words
A programmable read only memory device according to anyone of claims 1 - 4 characterized in that said volatile memory means (5042) comprises a plurality of flip flop circuits (FFO, FF1....FF(n-l).
Claim 7
Dependent Claim
27 words
A programmable read only memory device according to anyone of claim 1 bis 4 characterized in that said volatile memory means (5045) comprises a shift register. (MO,Ml...M(n-1).
Claim 8
Dependent Claim
165 words
A memory system for storing principal data receiving external address data and using key data provided in said memory system characterized in non-volatile memory means (71)for storing said key data; means (2) for processing the sequence of writing said principal data in said memory system using said key data and reading said stored principal data from said memory system using said key data; and a programmable read only memory device (52) for storing said principal data receiving said external address data and said key data, said memory device (52) comprising: a plurality of address input terminals (TO,Tl..T(n-1) for receiving said external address data; a plurility of non-volatile memory cells (501) for storing said principal data; volatile memory means (5042,5045) for storing said key data; address converting means (504) for converting said external address data into internal address data according to said key data stored in said volatile memory means (5042,5045); and means (502) for accessing said non-volatile memory cells designated by said internal address data.
Claim 9
Dependent Claim
165 words
A memory system for storing principal data receiving external address data and using key data provided in said memory system characterized in non-volatile memory means (71)for storing said key data; means (2) for processing the sequence of writing said principal data in said memory system using said key data and reading said stored principal data from said memory system using said key data; and a programmable read only memory device (52) for storing said principal data receiving said external address data and said key data, said memory device (52) comprising: a plurality of address input terminals (TO,Tl..T(n-1) for receiving said external address data; a plurility of non-volatile memory cells (501) for storing said principal data; volatile memory means (5042,5045) for storing said key data; address converting means (504) for converting said external address data into internal address data according to said key data stored in said volatile memory means (5042,5045); and means (502) for accessing said non-volatile memory cells designated by said internal address data.
Claim 10
Dependent Claim
48 words
A memory system according to claim 7 characterized in that said programmable read only memory device (52) comprises transfer gate means (5041,5044) controlled by a control signal (Ø), said transfer gate means(5041,5044) transferring said key data applied to said address input terminals to said volatile memory means (5042,5044)..
Claim 11
Dependent Claim
25 words
A memory system according to claim 7 or 8 characterized in that said address converting means (504) comprises a plurality of logical gate circuits (5043).
Claim 12
Dependent Claim
23 words
A memory system according to claim 9, characterized in that said logical gate circuits (5043) comprises a plurality of exlusive OR gates (GO.G1...G(n-1).
Claim 13
Dependent Claim
28 words
A memeory system according to any one of claims 7 - 10, characterized in that said volatile memory means (5042) comprises a plurality of flip flop circuits (FF1,FF2....FF(n-1).
Claim 14
Dependent Claim
25 words
A memory system according to any one of claims 7 - 10, characterized in that said volatile memory means (5045) comprises a shift register (M0,M1....M(m-1).
References Cited (Backward Citations)
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