JPH01284932A - Access device to internal memory area - Google Patents

Abstract

PURPOSE:To ensure the transfer of data to an internal memory even in case a system has the abnormality by using a means with which the system is forcibly stopped and meanwhile an external device gives an access to a memory bus via an interface. CONSTITUTION:A back-up memory 3 is connected to an internal memory bus 8 via an external interface 4 and at the same time a signal is supplied to a CPU 5 to stop a system. Then a pseudo control signal needed for memory access is inputted from a control signal generating circuit 10 while the system stops. Then the data prepared in the memory 3, for example, are loaded into an internal memory or the data are read out of a RAM 6 and saved into the memory 3.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an access device for an internal memory area that can directly exchange data with an internal memory.

(Prior art) Conventionally, there has been a technology to retrieve the data stored in the internal memory without losing it when the system falls into an abnormal state and the data in the internal memory cannot be retrieved through the normal route. Various types have been developed.

One method is to use external storage means, and another method is to assemble the internal memory so that it can be physically separated from the system, so that if the system goes down, the internal memory can be removed. This is a replacement for another system. This latter method uses a printed circuit board (PC
B) etc. are used.

(Problems to be Solved by the Invention) Such conventional techniques have drawbacks such as an increase in the price of the system and a decrease in the degree of freedom in system configuration. Furthermore, even if the system were to go into an abnormal state due to a software problem, it would have to be dealt with by replacing the hardware, posing a major cost problem.

The present invention was made to solve the above problems, and
The purpose of the present invention is to provide an access device to an internal memory area that can exchange data with the internal memory when the system is in an abnormal state and the data in the internal memory cannot be retrieved through a normal route.

(Means for Solving the Problems) According to the present invention, in an access device for an internal memory area that exchanges data with the internal memory when the system of an electronic circuit having an internal memory goes down, a memory bus of the electronic circuit is provided. An internal device comprising an external interface to be connected, a control signal generating means for inputting a predetermined control signal from outside the system via this external interface, and an external device including a backup memory connected to the internal memory. A device for accessing a memory area can be provided.

(Function) The device for accessing an internal memory area of the present invention forcibly stops the system using the control signal, and during that time, the external device accesses the memory bus from the interface to load or load predetermined memory contents. The feature is that it saves.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

The block diagram shown in the drawings shows an input/output device 1 and a target system to which this device is connectable. The input/output device 1 is provided with a backup memory 3 having a predetermined capacity such as RAM (random access memory),
On the other hand, an external interface 4 connectable to the input/output device 1 is provided in advance on the target system 2 side. The system 2 is composed of a CPU 5, a RAM 6, a memory control circuit 7, etc., and its internal memory path 8 is connected to the external interface 4.

In the electronic circuit system 2 having an internal memory such as the RAM 6, in order to exchange data with the internal memory when the system goes down, it is first necessary to stop the function of the CPU 5. The input/output device 1 includes a stop control signal generation circuit 9 that generates a stop control signal for this purpose;
The memory control circuit 7 also includes a control signal generation circuit 10 for controlling the memory control circuit 7 and accessing a predetermined area of the RAM 6. The connection means 4' corresponding to the external interface 4 is used to exchange data with the backup memory 3 when the system 2 falls into an abnormal state and cannot output the memory contents through the normal route. That's what I do.

That is, the backup memory 3 is connected to the internal memory path 8 through the external interface 4, and at the same time, a signal for stopping the system is supplied to the CPU 5. after that,
While the system is stopped, a pseudo control signal necessary for memory access is input from the control signal generation circuit 10, and data stored in the backup memory 3 is loaded into the internal memory, or from the RAM 6. It can be read out and saved in the backup memory 3. The control signal generation circuit 10 enables address specification of the RAM 6 or the backup memory 3, and the data can be transferred to another system without destroying the data in place of the electronic circuit system that has gone down. can.

In this way, according to the method of the above embodiment, it is possible to cope with a system failure without impairing the degree of freedom of the system.

As above, this invention has been described in some detail with respect to its most preferred embodiment, but the description of the preferred embodiment does not include variations in detailed parts of the configuration or contrary to the spirit of the invention as described in the claims. It is clear that various modifications or combinations thereof may be made.

(Effects of the Invention) As explained above, according to the present invention, even if the CPU of the target system does not operate normally, memory contents can be read from the outside or predetermined contents can be written to a predetermined area from the outside. Furthermore, it is possible to provide a device for accessing an internal memory area that allows for free system configuration without impairing system maintainability and is cost-effective compared to conventional methods.

[Brief explanation of the drawing]

The figure is a block diagram showing one embodiment of the present invention. 1... Input/output device, 2... Target system, 3
...Backup memory. Patent applicant Representative of FANUC Co., Ltd. Patent attorney Minoru Tsuji

Claims (3)

[Claims] (1) In an access device for an internal memory area that exchanges data with the internal memory when the system of an electronic circuit having an internal memory goes down, an external interface connected to a memory bus of the electronic circuit, and an external interface connected to the memory bus of the electronic circuit; and an external device including a backup memory connected to the internal memory. An apparatus for accessing an internal memory area, wherein the external device accesses the memory bus from the interface to load or save predetermined memory contents. (2) The device for accessing an internal memory area according to claim 1, wherein the external device has a backup memory configured as RAM. (3) Claim (1) characterized in that the control signals input from the external device via the external interface include a stop control signal for stopping the CPU and a transfer control signal for the internal memory. The device for accessing the internal memory area described in .