JPH04336694A - Memory card - Google Patents

Abstract

PURPOSE:To provide a semiconductor storage device with a security function by judging input data and enabling a memory IC. CONSTITUTION:Optional input data from an I/O signal 4 are compared with inherent data 8 by logical elements 9, and when both the data coincide with each other, the memory IC 1 is enabled. In the case of anticoincidence of both the data, the IC 1 is turned to a stand-by state. Since the memory IC can not be accessed until the inherent data 8 are inputted from the I/O signal 4, the data can be protected.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to security of semiconductor memory devices.

0002

2. Description of the Related Art FIG. 3 is a block diagram showing the structure of a conventional semiconductor memory device. In the figure, 1 is a memory IC, 2
3 is a selection signal of the semiconductor memory device, 3 is a decoder, 4 is an input/output signal of the semiconductor memory device, 5 is an output control signal, 6 is an address signal, and 7 is a program signal.

Next, the operation will be explained. Memory IC1
In the read cycle for reading out the written contents, the address to be read is input by the address signal 6. Next, by setting the selection signal 2 of the semiconductor memory device to "L", the memory IC1 is selected from the decoder 3 and becomes standby. By setting the output control signal 5 to "L", the contents written in the memory IC 1 are outputted to the input/output signal 4. Further, when the memory card selection signal 2 is set to "H", the decoder 3 does not output any output and the memory IC 1 becomes standby.

0004

Problem to be Solved by the Invention Since the conventional semiconductor memory device is configured as described above, it is difficult to set the selection signal to "L".
However, since the written contents of the memory IC can be read, there is a problem that the written contents are not secured.

The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide a memory card that can provide security for a semiconductor storage device.

[0006]

A memory card according to the present invention compares and determines input data and unique data, and enables a memory IC based on the result.

[0007]

[Operation] The memory card according to the present invention compares input data and unique data, and if they match, enables the memory IC.

[0008]

【Example】

Example 1. An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, 1 to 7 are 1 to 7 shown in the conventional example of FIG.
Since it is the same as 7, the explanation will be omitted. 8 is unique data provided inside the semiconductor memory device, 9a and 9b are logic elements that compare the input data and the unique data 8, and 10 is a logic element 9a.
, 9b, and 11 is an AND circuit.
This is a latch circuit that holds the output of the circuit 10.

Next, the operation will be explained. When the same operation as that shown in the conventional example of FIG.
C1 becomes inaccessible.

When arbitrary data is input from the input/output signal 4, the input data and the unique data 8 are compared by the logic element 9. If there is a mismatch, the AND circuit 10 goes “L”
The memory IC1 is not selected by the decoder 3 and enters a standby state, the input/output signal 4 becomes high impedance, and the memory IC1 becomes inaccessible.

If the input data and the unique data 8 match, the AND circuit 10 outputs "H" and the decoder 3
Memory IC1 is selected from. Once "H" is output from the AND circuit 10, it is held by the latch circuit 11, and even if "L" is output from the AND circuit 10, the output of the latch circuit 11 is "H". Next, by setting the output control signal 5 to "L" and the selection signal 2 to "L", the memory IC
The written contents are outputted to the input/output signal 4 from 1 to 4.

Example 2. Note that although the above embodiment has been described with respect to a read-only memory card, the same effects as in the above embodiment can also be obtained with a read/write memory card. In FIG. 2, 1 to 8, 9a, 9b, 10,
Since 11 is the same as 1 to 8, 9a, 9b, 10, and 11 shown in FIG. 1, the explanation will be omitted. When writing data to the memory IC1, the same data as the unique data 8 is inputted from the input/output signal 4, and the memory IC1 is left in a state where it is selected by the decoder 3. Selection signal 2 and write signal 12
is set to "L" and data is written to the memory IC1.

[0013]

As described above, according to the present invention, since the input data is determined and the memory IC1 is enabled, security is effectively protected.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of a semiconductor storage device according to an embodiment of a memory card according to the present invention.

FIG. 2 is a block diagram showing the configuration of a readable/writable semiconductor memory device according to another embodiment of the present invention.

FIG. 3 is a block diagram showing the configuration of a conventional semiconductor memory device.

[Explanation of symbols]

1 Memory IC 2 Selection signal 3 Decoder 4 Input/output signal 5 Output control signal 6 Address signal 7 Program signal 8. Unique data 9 Logic element 10 AND circuit 11 Latch circuit 12 Write control signal

Claims (1)

[Claims] 1. A memory card characterized in that a semiconductor memory device having a plurality of semiconductor memories and peripheral circuits is provided with a logic element group and a latch circuit for comparing internally set unique data and input data.