Memory cartridge including a key detector for inhibiting memory access and preventing undesirable write operations
First Claim
1. A memory cartridge removably attachable to a data processing apparatus, said memory cartridge comprising:
- a random access memory (RAM) for storing data generated by said data processing apparatus;
a read only memory (ROM) for storing a program executable by said data processing apparatus and for storing first multi-bit key data for allowing said data processing apparatus to access said RAM;
holding means for receiving and holding multi-bit key data read from said ROM by said data processing apparatus in accordance with said program;
key detecting means for generating a first key detection signal when said multi-bit key data read from said ROM and held in said holding means corresponds to said first multi-bit key data; and
a control circuit for generating a RAM selection signal for enabling said RAM in response to said first key detection signal and a power detection signal.
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Accused Products
Abstract
A memory cartridge which may be loaded in an attachable/detachable manner to a data processing apparatus, such as a hand-held electronic game machine having a central processing unit (CPU), includes logic control circuitry, a program read only memory (ROM), a bank changing circuit, and external random access memory (RAM). The external RAM is backed-up by a battery. First key data and second key data are initially stored in the program ROM. After a power source of the data processing apparatus is turned-on and a power source voltage reaches a predetermined value, a reset signal is provided to the memory cartridge to enable circuits on the memory cartridge. When the first key data is read from the program ROM and the reset signal is detected, the external RAM may be accessed by the CPU to read and write information from/into the external RAM. When the second key data is read from the program ROM, the CPU is inhibited from such access to the external RAM.
82 Citations
18 Claims
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1. A memory cartridge removably attachable to a data processing apparatus, said memory cartridge comprising:
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a random access memory (RAM) for storing data generated by said data processing apparatus; a read only memory (ROM) for storing a program executable by said data processing apparatus and for storing first multi-bit key data for allowing said data processing apparatus to access said RAM; holding means for receiving and holding multi-bit key data read from said ROM by said data processing apparatus in accordance with said program; key detecting means for generating a first key detection signal when said multi-bit key data read from said ROM and held in said holding means corresponds to said first multi-bit key data; and a control circuit for generating a RAM selection signal for enabling said RAM in response to said first key detection signal and a power detection signal. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A memory cartridge removably attachable to a data processing apparatus which generates write and read signals, address signals, and execution data for executing a desired program, comprising:
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data input terminals for receiving data supplied from said data processing apparatus; address input terminals for receiving the address signals supplied from said data processing apparatus; a random access memory (RAM) having data inputs connected to said data input terminals and address inputs connected to said address input terminals; a read only memory (ROM) for storing said program and first multi-bit key data for allowing said data processing apparatus to access said RAM; holding means, connected to said data input terminals, for holding multi-bit key data read from said ROM by said data processing apparatus in accordance with said execution data; key detecting means for generating a first key detection signal when said first multi-bit key data read from said ROM and held in said holding means corresponds to said first key data; and a control circuit for generating a detection output signal in response to an inactive ROM selection signal, a power detection signal, and said first key detection signal, wherein writing of data into said RAM is enabled in response to said detection output signal and a write signal. - View Dependent Claims (8, 9, 10, 11, 12, 13, 14)
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15. A memory cartridge removably attachable to a data processing apparatus, comprising:
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a random access memory (RAM) for storing data generated by said data processing apparatus; a read only memory (ROM) for storing program instructions executable by said data processing apparatus, first multi-bit key data for allowing said data processing apparatus to access said RAM, and second multi-bit key data for preventing said data processing apparatus from accessing said RAM; a register for holding key data read from said ROM by said data processing apparatus in accordance with said program instructions; a key detector for generating a first key detection signal when said key data read from said ROM and held in said register corresponds to said first multi-bit key data and a second key detection signal when said key data read from said ROM and held in said register corresponds to said second multi-bit key data; a control circuit for enabling said RAM at least in part in response to said first key detection signal to permit said data processing apparatus to write data into said RAM and for disabling said RAM in response to said second key detection signal. - View Dependent Claims (16, 17, 18)
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Specification