JPS63301384A - Method for inspecting write of portable storage medium - Google Patents

Abstract

PURPOSE:To inspect memory write without being affected by distributed capacity between wirings, by sending data different from write data onto a data bus after writing the data, and after that, reading the write data. CONSTITUTION:The write data is set in a CPU1, and it is sent onto the data bus 7, and the data is written on a memory 3. After that, another data different from the write data is set in the CPU1. Then, the another data is send onto the bus 7. Thereby, the data stored in the distributed capacity of the bus 7 in a preceding operation, that is, the same data as the write data is changed to the another data. Next, the data is read out from the memory 3 to the CPU1. The data read out in such way is placed in the CPU1 and is compared with the write data. As a result of comparison, it is decided that read out data is not equal to the write data is decided as the true error of the memory 3.

Description

[Detailed Description of the Invention] [Objective of the Invention] (Industrial Application Field) The present invention provides a method for writing data to a portable storage medium.
The present invention relates to a write inspection method for a portable storage medium in which written contents are confirmed by successively reading and comparing the read data.

(Prior Art) A write verification method for inspecting written data in a memory built into a so-called IC card, which is a portable storage medium formed in a card shape and incorporating an integrated circuit such as a CPU and a memory. This is done using an EPROM writer, etc., as in conventional machines.

i.e. buffer all data first? , and prepares the write data in the register (RAM) of the CPU. Then, the write address of the memory is set, the memory is set to the write enable state, and the write data is sent to the data bus and written to the memory. After writing data to all addresses, set the memory to read mode and read the data from the memory. This successive data is compared with the write data stored in the buffer to check whether the data has been written correctly.

After writing the data to the memory of the IC card in this way, the written data can be continuously read and compared.
A write check of the memory of the C card is being executed.

(Problems to be Solved by the Invention) As mentioned above, an IC card usually has at least two chips consisting of a CPU and a memory, and the data bus etc. between these chips are naturally connected by wiring. Because distributed capacitance usually occurs between the ground and the ground,
This distributed capacitance affects the data when writing or reading data into the memory, causing the problem that incorrect data may be written or read. Specifically, if some data is written into memory via a data bus, the same data as this write data will remain accumulated in the distributed capacity of the data bus, so the next memory read operation will be performed. In this case, the data stored in the distributed capacitance of the data bus may be latched as read data. Therefore, even if the memory is defective, the data stored in the distributed capacitance of the data bus is latched when read, and the memory is incorrectly judged to be normal. There is a problem that it cannot be detected accurately.

The present invention has been made in view of the above, and an object of the present invention is to provide a portable storage medium that can accurately perform a memory write test without being affected by distributed capacitance between wirings. The objective is to provide an inspection method.

[Structure of the invention]

(Means for Solving the Problems) In order to solve the above problems, the writing inspection method for a portable storage medium of the present invention is such that after writing data to a portable storage medium, the written data is continuously In a write inspection method for a portable storage medium in which the written contents are confirmed by reading and comparing, after predetermined data is written to the portable storage medium via a data bus, the predetermined written data and sending different data onto the data bus;
The gist is to read the written data from the portable storage medium after this sending.

[Effect]

In the write inspection method for a portable storage medium of the present invention, after data is written to the portable storage medium via a data bus, data different from the written data is sent onto the data bus, and after this sending, data is written to the portable storage medium via a data bus. Reading data from a portable storage medium.

(Example) Hereinafter, the present invention will be explained in detail using the drawings.

Figure 1 shows the portable recorder of the present invention! FIG. 2 is a flowchart showing an example of a processing operation for carrying out a writing inspection method for a portable storage medium, and FIG. 2 shows a circuit configuration of a portable storage medium, that is, an IC card, to which the writing inspection method for a portable storage medium is applied. It is a block diagram.

As shown in FIG. 2, the IC card has a CPU 1 and a memory 3, each of which is an integrated circuit chip, for storing and processing various data, and an address bus 5, a data bus 7 and a chip enable line 11. Distributed capacitance is generated in the wiring that constitutes these buses, for example, between the ground and the ground, and in particular, as shown in the figure, the distributed capacitance 9 connected to the data bus 7 is used for testing data writing to the memory 3, In other words, it has an adverse effect on the write verify operation.

In other words, in the conventional write verify operation,
When data is sent to and read from the memory 3 via the data bus 7, the write data is accumulated in the distributed capacitor, so when the write data is read from the memory 3 following the write operation, it is accumulated in the distributed capacitor. However, in the write inspection method for a portable storage medium of the present invention, the written data stored in the distributed capacitor is latched as read data, e.g. By changing the data to data that has an exclusive OR relationship with the data, that is, inverted data, etc., it is possible to receive only the true write data read from the memory 3, thereby accurately detecting defects in the memory 3. It is something to do.

FIG. 1 is a flowchart showing a write verify operation based on such an operating principle. The operation will be explained below according to this flowchart.

First, write data is set in the register of CPU 1, and a write address is set (steps 110 and 120).

Then, the write data set in the register is sent to the data bus 7 (Do-D7), the memory 3 is set to write enable, the memory 3 is set to high impedance, and the data is written to the memory 3 (step 130).
-160>. Note that in this state, the same data as the write data is accumulated in the distributed capacitance of the data bus 7.

After writing the data to the memory 3, other data different from the write data, such as exclusive OR data, for example, inverted data of the write data, is set in the register (step 170). This other data is then sent to the data bus 7 (step 180). As a result, the data accumulated in the distributed capacitance of the data bus 7 in the write operation, that is, the same data as the write data, is changed to different data.

Next, the memory 3 is made read-enabled and data is read from the memory 3 to the CPLll (step 190.20).
0). The thus read data is compared with the written data in the CPU 1 (step 210). As a result of this comparison, if the read data is not equal to the write data, it can be determined that there is a true error in the memory 3, and error processing for the memory 3 is performed (step 220). If the read data is equal to the 8-write data, the memory 3 is normal and the write operation of the next address is continued (step 230).

〔Effect of the invention〕

As explained above, according to the present invention, after data is written into a portable storage medium via a data bus, data different from the written data is sent onto the data bus, and after this sending, the written data is is being read from a portable storage medium, so even if there is a distribution capacity Φ on the data bus and the written data is temporarily stored in the distribution capacity, the distribution can be changed by sending different data to the data bus. The write data stored in the capacitor is changed to different data, and the next read operation does not latch the same data as the write data from the distributed capacitor, so it is not affected by the distributed capacitor. It is possible to latch data that has been truly read from the memory, perform a memory write test accurately, and reliably detect memory defects.

[Brief explanation of drawings]

FIG. 1 is a flowchart showing an example of processing operations for carrying out the write inspection method for a portable storage medium of the present invention, and FIG. 2 is a portable storage medium to which the write inspection method for a portable storage medium of the present invention is applied. FIG. 2 is a circuit configuration diagram of an IC card. 1...CPU, 3...Memory, 7...Data bus, 9...Distributed capacity

Claims (1)

[Claims] In a write inspection method for a portable storage medium in which data is written to a portable storage medium and then the written data is read out and compared to confirm the written contents, a data bus is connected to the portable storage medium. After writing predetermined data through the data bus, data different from the predetermined write data is sent onto the data bus, and after this sending, the write data is read from the portable storage medium. Method for inspecting writing on media.