JPS61256449A - Bus diagnosis system - Google Patents

Abstract

PURPOSE:To attain the simple checking of buses with no increase of the hardware quantity by reading the data written previously when a power supply is applied and using the difference from a writing mode to check a bus. CONSTITUTION:The check data is written to a data area 5 by the program of a central processing unit 3 in an initial register mode of a microdisk device 4. Then the check data is read when a system power supply is applied and compared with the writing data obtained in the initial register mode according to the program of the unit 3. It is decided that a bus has the abnormality if a difference is obtained from said comparison. Thus the bus can be easily checked without increasing the hardware quantity.

Description

[Detailed Description of the Invention] [Summary] The present invention provides an external device and a main control device (central processing unit).
This is a path diagnosis method that can perform hardware pass checks during bus checks.

The present invention relates to a method for checking a bus that connects processing units.

[Conventional technology]

Conventionally, a bus check of an external storage device in a central processing unit has been performed using a data parity check method. This method uses a parity check bit and provides parity check in hardware (ECC circuit) to perform parity check during data transfer.

[Problem that the invention seeks to solve]

This conventional method has the disadvantage that an extra check circuit must be provided, making it difficult to downsize the device.

The present invention has been made in view of the above-mentioned drawbacks, and it is an object of the present invention to provide a method that allows bus checks to be easily performed without increasing the amount of hardware.

[Means for solving problems]

The purpose is to read the check data written to the data area (5) by the program (6) at the time of initial registration of the microdisk device 4 when the system power is turned on, and compare it with the same data written at the time of the initial registration. This is achieved by a bus diagnosis method in which if there is a difference in the comparison results, it is assumed that there is an abnormality in the bus.

[Effect]

In response to the need for miniaturization of control devices using external storage devices, the present invention provides a means for bus checking to reduce the number of ICs for parity checks, etc. in response to the need for miniaturization of control devices using external storage devices. By writing check data in a predetermined format in a predetermined area of the system, and reading and checking the data each time the system power is turned on,
This method easily detects data bus abnormalities.

〔Example〕

The present invention will be described in detail below with reference to the drawings.

FIG. 1 is a principle block diagram showing an embodiment of the present invention.

In the figure, 1 is a data bus, 2 is a driver/receiver, 3 is a central processing unit (CPU or microprocessor chip), 4 is a microdisk device, 5 is a data area, and 6 is a program.

FIG. 2 is a diagram showing details of the contents of a data area showing an embodiment of the present invention.

In this explanation, the same symbols represent the same contents.

At the time of initial registration of the microdisk device 4, the program 6 of the central processing unit 3 writes 8 bytes of data corresponding to each data bit (8 bits) as shown in FIG. 8 into the data area 5. In other words, "0000 in FIG.
0001” is the first bit check data,
“oooooo.

10" is the check data for the second bit. "1oo
oooooo" is the check data for the 8th bit. By reading the check data when the system power is turned on and comparing it with the same data written at the time of initial registration using the program 6 in the central processing unit 3, etc. If they do not match, it is known that there is an abnormality in the data bus or microdisk.Since this error check for microdiscs is a well-known technique, the data bus can be checked using the check results.

〔Effect of the invention〕

As explained above, according to the present invention, there is an effect that bus checking can be easily performed without increasing the amount of hardware.

[Brief explanation of the drawing]

FIG. 1 is a principle block diagram showing an embodiment of the present invention. FIG. 2 is a diagram showing details of the contents of a data area showing an embodiment of the present invention. Explanation of symbols: 1 is a data bus, 21 is a driver/receiver, 3 is a central processing unit (CPU or microprocessor chip), 4 is a microdisk device, 5 is a data area) 6 is a program.

Claims (1)

[Claims] The check data written in advance in the data area (5) of the microdisk device (4) is read when the system is powered on, and the path is checked by checking the difference between the read check data and the data at the time of writing. A path diagnosis method characterized by performing the following.