JPS60254258A - Detecting method for breakdown of rom memory data - Google Patents

Abstract

PURPOSE:To always attain a fault check with no use of an external device by incorporating a breakdown detecting method for data converted into a ROM to a part of a system control program. CONSTITUTION:A microcomputer 1 contains a CPU2, memory 3, RAM4, RAM5, input device 6 and an output device 7. An external memory 8 is also connected to the computer 1. The total value of the fixed data stored in the ROM5 is stored to the final area of the ROM5, then compared with the total value of data obtained when the data are read out of the ROM5. Thus the breakdown of the ROM data can be detected.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a method for detecting destruction of data read from a read-only memory (ROM).

[Prior art]

Conventionally, there has been a data processing apparatus related to this type of method as shown in FIG. In the figure, 1.1 is a microcomputer, which consists of a processor (CPU) 2, a memory 8 that stores a system control program, a random access memory, and a memory (RAM) that stores variable data.
4% A read-on memory 9, a memory (ROM) 5 for storing fixed data, an input device 6, and an output device 7 are provided. 8 is an external memory consisting of a magnetic tape, a magnetic disk, or the like.

In order to check whether the contents of the fixed data stored in the memory 1J5 are not destroyed, first store this data in the memory 5, that is, convert it into a ROM, and store the same contents as the data at this time in the external memory 8. to be memorized. These two data contents are read into the memory 4 under the control of the processor 2, and then a data content comparison program in the system control program is run to compare the data contents stored in the memories 4 and 5. If the two do not match, it is determined that there is an abnormality in the memory 5.

゛Since the conventional method is configured as described above, an external memo IJ with the same contents as the contents stored in the memory is always stored.
Since it is necessary to connect the device to a microcomputer, the preparation and operation of these devices becomes complicated, and there are problems in that there are many erroneous operations.

[Summary of the invention]

This invention was made to solve the problems of the conventional method as described above, and by calculating the total amount of data to be stored in the ROMK and storing this total value in the final part of the ROM storage area, It is an object of the present invention to provide a memory data destruction detection method that can self-detect destruction of ROMized data in a microcomputer system control program.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings. Second
The figure is a memory map diagram of the memory 5, where 9 is a fixed data area handled by the system control program, and 10 is a total data area that stores the total of these fixed data. FIG. 3 is a flowchart for writing data into the memory 5 as shown in the memory map shown in FIG. FIG. 4 is a flowchart for detecting whether data written in the memory 5 is corrupted.

First, in step 11, the ninth register, which sums up the data to be written into the memory 5, is set to 0.

In step 12, data is written word by word,
At step 18, the data contents are added to the total register each time. In step 14, it is checked whether there is still data, and when all data has been written and totaled, this total data is written in the final part of the storage area of the memory 5 in step 15, and data writing to the memory 5 is completed.

Detection of destruction of ROMized data will be explained with reference to the flowchart of FIG. For example, this destruction detection is performed when the system is initialized and the power is turned on. In step 16, the register for summing the data written in the memory 5 is set to 0, in step 17 the data is read word by word, and in step 1B, the sum is added to the register. When the totalization of the fixed data area 90 is completed as determined in step 19, the contents of the total data area 10 are read out in step 20, and compared with the contents of the total register in step 21. If the two match, the contents of the memory 5 are determined to be normal in step 22, and the fixed data in the memory 5 can be permitted to be used in the system control program. If they do not match, the contents of the memory 5 are treated as being destroyed in step 28, and use of this fixed data is prohibited.

If the memory 4 is used in the same way as the memory 5, that is, used to store fixed data, the same effects as in the above embodiment can be obtained.

〔Effect of the invention〕

As described above, according to the present invention, the destruction detection of ROM data is incorporated into a part of the system control program, so that the microcomputer can perform self-diagnosis. This has the effect that it is possible to check for abnormalities.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of the configuration of a data processing device, FIG. 2 is a memory map diagram of the memory (ROM) according to the present invention, FIG. 3 is a flowchart for writing data to the memory map shown in FIG. 2, and FIG. is a flowchart for detecting destruction of data in the ROM shown in FIG. 2; DESCRIPTION OF SYMBOLS 1...Microcomputer, 2...CPU, 3°4.5...Memory, 6...Input device, 7...Output device, 8...External memory, 9...Fixed data region,
10...Total data area. Patent applicant Mitsubishi Electric Corporation Figure 1 Figure 2 Figure 3 Procedural amendment (voluntary) Indication of the case by the Commissioner of the Japan Patent Office Patent application No. 1987-109349 Name of the invention Read-only memory data Representative Hitoshi Katayama Department First agent Postal code: 105 Address: 1-4-10-5 Nishi-Shinbashi, Minato-ku, Tokyo, Column 6 of the detailed description of the invention in the specification subject to amendment, and the description of the contents of the amendment, are corrected as follows.

Claims (1)

[Claims] A read-only memory that stores fixed data read by a processor that executes data processing includes a first area for storing the fixed data, and a second area for storing the sum of the fixed data stored in the first area. Set,
When data is read from the first area, the sum of the data is calculated, and the sum is compared to see if it matches the value of the data stored in the second area. If no match is detected, the sum of the data is calculated. A read-only memory data destruction detection method that determines that data in a first area is destroyed.