Title:
CIRCUIT FOR PREVENTING DECODING OF CIPHER CODE DATA IN SEMICONDUCTOR MEMORY
Document Type and Number:
Japanese Patent JPH10105469
Kind Code:
A
Abstract:
To prevent an enciphering code from being decoded by reading an area which is not used in an EPROM cell.
A logical operation is executed by a NAND gate ND1 concerning data which is read from the EPROM cells 31B1-31BmB, and latched by the respective second latches LT2 of read data enciphering processing part 33A-33M. When at least one bit value is 'zero', an output detecting signal DET becomes 'one' and latched data is enciphered and outputted. When the whole bit values are 'zero', the output detecting signal DET becomes 'one' and the output of enciphering code data is interrupted.
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Inventors:
SUN SHIKU KIMU
Application Number:
JP19449497A
Publication Date:
April 24, 1998
Filing Date:
July 18, 1997
Export Citation:
Assignee:
LG SEMICON CO LTD
International Classes:
G06F12/14; G06F21/60; G06F21/62; G06F21/72; G11C8/20; G11C16/00; G11C16/22; H04L9/36; (IPC1-7): G06F12/14
Attorney, Agent or Firm:
Fumio Sasashima (1 person outside)