JPH04352049A - E2 prom program test system - Google Patents

Abstract

PURPOSE:To check the normality of a program by calculating a check sum again before executing the program and comparing the calculated value with that obtained at normal time. CONSTITUTION:A program to be executed in a CPU is written in an area A. On the other hand, the check sum of the program previously found out by calculation is written in an area B. In the case of executing the program, the CPU reads out the program from the area A and reads out the check sum from the area B. Before executing the program, the CPU calculates the check sum of the read program and compares the calculated check sum with that read out from the area B. When both the values coincide with each other as the compared result, the normality of the program is judged and the program is executed. When there is discrepancy between both the values, the existence of abnormality in the program is recognized.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for testing a program on an E2 PROM, and more particularly to confirming the normality of a program written on an E2 PROM.

0002

[Prior Art] Conventionally, there has been no method for checking the normality of a program written on an E2 PROM.
2. The program written on the PROM is executed by the central processing unit without checking its normality, and an abnormality in the program is detected as a result of the execution.

0003

[Problem to be solved by the invention] As mentioned above, conventionally,
The program on the E2 PROM is being executed without being able to confirm its normality. Therefore, if a program malfunctions, it cannot be detected, resulting in a lack of reliability.

The present invention provides an E2 PR system that detects abnormalities in a program on an E2 PROM before executing the program.
The purpose is to provide a program testing method on OM.

[0005]

[Means for Solving the Problems] According to the present invention, E2
This is an E2 PROM program test method for checking the normality of a program written in a PROM.
2 Write a pre-calculated checksum of the program in a predetermined area of PROM, calculate and obtain the checksum of the program when the central processing unit executes the program, and write the checksum of the program calculated in advance and the checksum of the program when the central processing unit executes the program. E
2. A program test method on E2 PROM is obtained, which is characterized in that the test sum is compared with the checksum written in PROM.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be explained with reference to the drawings. Figure 1 shows the memory map on the E2 PROM. A program to be executed by the central processing unit is written in area [A]. On the other hand, in area [B], a check sum of this program calculated in advance is written.

When the central processing unit executes a program, it reads the program from area [A] and also reads the program from area [A].
Read the checksum from [B]. The central processing unit calculates a checksum of the read program before executing the program. Then, check sum read from area [B] and check sum obtained by calculation.
Compare with Sam. As a result of the comparison, if these checksums match, the program is determined to be normal and is executed. Furthermore, if they do not match, it is recognized that there is an abnormality in the program.

FIG. 2 shows an example of check sum calculation. Checksum adds information bit by bit. However, carry shall be ignored.

[0009]

Effects of the Invention As explained above, the present invention recalculates the checksum before executing the program and
The normality of the program can be confirmed by comparing it with the normal state written in the PROM, and the E2 PRO
This has the effect of improving the reliability of M.

[Brief explanation of the drawing]

[Figure 1] E2 PROM to which the present invention is applied is 64kb
This is a memory map in case of it size.

FIG. 2 is a diagram for explaining a check sum calculation method.

Claims (1)

[Claims] 1. An E2 PROM program test method for confirming the normality of a program written in an E2 PROM, wherein a pre-calculated check sum of the program is written in a predetermined area of the E2 PROM, and a When the processing device executes the program, a checksum of the program is calculated and compared with the checksum written in the E2 PROM. Features E2 PROM program test method.