Electrical computers and digital processing systems: memory – Storage accessing and control – Control technique
Reexamination Certificate
1994-12-02
2001-09-25
Nguyen, Hiep T. (Department: 2187)
Electrical computers and digital processing systems: memory
Storage accessing and control
Control technique
C380S043000, C713S152000
Reexamination Certificate
active
06295590
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a semiconductor memory apparatus.
2. Description of the Prior Art
Generally, a semiconductor memory apparatus outputs data stored therein when an address signal and a reading signal are inputted thereto. On the other hand, most of the semiconductor memories are general-purpose products which are compatible with one another even though made by different manufacturers.
For these reasons, it is easy to find out what data are stored in a semiconductor memory, so that it may be possible to illegally copy the data stored in the memory to provide it in another apparatus in order that various functions can be used without permission. For example, in the case of the satellite broadcasting for which viewers have to pay, the receivers are programmed so that only contractors can receive the satellite broadcasting. However, the satellite broadcasting can be received without permission by reading out the contents of the memory in which the program is stored, copying them to another memory and providing the memory in a receiver. Such an illegal use can also be made in the case of apparatuses such as game apparatuses.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a semiconductor memory apparatus from which stored data cannot easily be taken out to prevent an illegal use of the data.
According to the present invention, a semiconductor memory apparatus incorporates a protecting circuit which causes data stored in a memory portion to be output by executing a key canceling sequence in response to an input of a signal from an external apparatus. According to such a feature, the data stored in the memory portion are output only when a key canceling signal, input from an external apparatus, is input to the protecting circuit to execute the key canceling sequence, so that the data are not output only by inputting an address signal and a reading signal to the memory apparatus. As a result, it is impossible to find out the contents of the program stored in the memory portion. The key canceling signal input from an external apparatus is supplied, for example, by a microcomputer which controls the memory apparatus.
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Arent Fox Kintner & Plotkin & Kahn, PLLC
Nguyen Hiep T.
Rohm Col, Ltd.
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