JPH0648472B2 - Back-up memory check method - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a back-up memory check system including a non-volatile memory that backs up a volatile memory.

[Background of the Invention]

A back-up memory that backs up a volatile memory such as a semiconductor memory with a non-volatile memory such as a magnetic disk is disclosed in, for example, Japanese Patent Laid-Open No. 58-194187, "Memory Device". Since such a backup memory cannot be directly written and read from the upper level, the following procedure must be performed to check the normality of the backup memory.

(1) Write specific data on the entire surface of the volatile memory.

(2) Stop access to the volatile memory and save the entire area to the backup memory.

(3) Turn off the power and then turn it on again.

(4) Wait for the saved data in the non-volatile memory to be transferred to the entire volatile memory.

(5) Read the entire volatile memory.

(6) Check the agreement with the data written in (1).

As described above, in order to check the normality of the backup memory, there is a problem in that it takes manpower at the time of turning off and on the power again in the step (3), which makes it impossible to perform automatic diagnosis only by the program.

[Object of the Invention]

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the drawbacks of the conventional check-up system of the backup memory and to provide a check-up system of the backup memory which can be performed without human intervention.

[Outline of Invention]

The main point of the present invention is to stop the saving operation from the volatile memory to the backup memory, and to make the command of pulling up the volatile memory from the backup memory programmable so that this command can be used in the following procedure. This is a check-up of the backup memory.

(1) Write specific data on the entire surface of the volatile memory.

(2) Stop access to the volatile memory and save the entire area to the backup memory.

(3) Set to cancel the data save operation.

(4) Write data different from that in (1) on the entire surface of the volatile memory.

(5) Set the pull-up operation from the backup memory to the volatile memory and transfer it to the entire volatile memory.

(6) Read the entire surface of the volatile memory.

(7) Whole surface Confirm the agreement with the data written in (1).

From the above, if the data in the volatile memory in item (7) has been rewritten from the data written in item (4) to the data written in item (1), the save operation and the pull-up operation to the backup memory can be performed. The normality can be confirmed, and the normality of the back-up memory can be performed by the instruction of only the program without human intervention.

Example of Invention

An embodiment of the present invention will be described below with reference to the drawings. In the figure, 1 is a host device, 2 is a volatile memory written (hereinafter abbreviated as W) and read (hereinafter abbreviated as R) from the host device 1, and 3 is a non-volatile memory that backs up the volatile memory 2. Back-up memory consisting of 4
Is a save instruction circuit that senses that the volatile memory 2 has been W and instructs that part to be saved in the backup memory 3. Reference numeral 5 is a backup memory 3 that is used when the power of the memory device is turned on. A pull-up instruction circuit for instructing the pulling up of data, 6 is a save operation inhibiting circuit for inhibiting the operation of the data save instruction circuit 4 in response to a command from the host device 1, and 7 is a backup memory 3 in response to a command from the host device 1. 8 is an AND gate, 9 is an OR gate, and 8 is an AND gate.

First, the operation of the backup memory 3 at the normal time in the figure will be described.

(1) W is applied to the volatile memory 2 from the host device 1.

(2) From the save instruction circuit 4, the portion which is W in (1) when there is no access from the host device 1 is backed up in the backup memory 3
Go to W.

(3) Continue executing the above (1) and (2), and match the contents of the backup memory with the latest data in the volatile memory 2.

(4) When the power is turned off and then turned on again, the pull-up instruction circuit 5 transfers the entire contents of the backup memory 3 to the volatile memory 2 so that the contents of the volatile memory 2 can be restored to the data when the power was turned off.

Next, the operation of the back-up memory 3 at the time of checking will be described.

(1) W specific data over the entire surface of the volatile memory 2.

(2) The save instruction circuit 4 saves the above data (1) in the entire back-up memory 3.

(3) Set the save operation prohibition circuit 6. As a result, the AND gate 8 inhibits the output of the save operation circuit 4.

(4) W data (for example, its inversion pattern) different from the item (1) is written on the entire surface of the volatile memory 2.

(5) Set the pull-up instruction circuit 7, and set the backup memory 3
To the volatile memory 2.

(6) R the entire surface of the volatile memory 2 and confirm that it matches the data written in (1).

By checking (6), the normality of the backup memory 3 is checked.

〔The invention's effect〕

According to the present invention, the check-up of the backup memory can be performed only by the program without the manual operation of turning the power off and on, and the self-diagnosis of the device can be facilitated.

[Brief description of drawings]

 FIG. 1 is a block diagram showing an embodiment of the present invention. DESCRIPTION OF SYMBOLS 1 ... Host device, 2 ... Volatile memory 3 ... Backup memory 4 ... Save operation instruction circuit 5, 7 ... Pull up instruction circuit 6 ... Save operation prohibition circuit 8 ... AND circuit, 9 ... OR circuit

Claims (1)

[Claims] 1. A back-up memory comprising a volatile memory and a non-volatile memory that saves the contents of the volatile memory each time writing is performed in the idle time of the operation of the volatile memory. The check-up method of the backup memory is characterized in that the cancellation of the backup and the transfer from the backup memory to the volatile memory are made possible by a command from the host for the diagnosis of the backup memory.