JP2842442B

PURPOSE:To realize various types of protective functions of the memory by a small quantity of units, to set the conditions to prevent the rewriting by providing the memory element for protective information, the temporary memory register of protective information and the address decision circuit, et...

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Bibliographic Details
Main Authors NAKAMURA HIDEO, SAWASE TERUMI
Format Patent
LanguageEnglish
Published 06.01.1999
Edition6
Subjects
CALCULATING
COMPUTING
COUNTING
ELECTRIC DIGITAL DATA PROCESSING
INFORMATION STORAGE
PHYSICS
STATIC STORES
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Summary:PURPOSE:To realize various types of protective functions of the memory by a small quantity of units, to set the conditions to prevent the rewriting by providing the memory element for protective information, the temporary memory register of protective information and the address decision circuit, etc. CONSTITUTION:When a chip selecting signal 43 and an address 41 are given, the contents of a memory element 151 for the data and a memory element 152 for protective information are read by respective sense amplifiers 341 and 342. The output of the amplifier 342 is set to a register 37 to store temporarily the protective information, and when the output 47 is '1', the data are read onto a data bus 42. When the output 47 of the protective information is '0', a driver 351 is controlled, the output is prohibited and the data are not sent to the bus 42. By adding the address decision circuit, the writing preventing data latch circuit, and the deleting preventing data latch circuit, the conditions to prevent the rewriting can be set. Namely, various types of the protective functions of the memory can be realized by a small quantity of the units and the conditions to prevent the rewriting can be set.
Bibliography:Application Number: JP19850090268