JPS6126154A - Device for adding and correcting equivalent contents of read-only memory - Google Patents

Abstract

PURPOSE:To correct and add easily the equivalently unrewritable contents of a ROM by temporarily transferring the contents of the ROM to a RAM and adding and correcting the contents of the RAM by the contents of another adding/ correcting information memory. CONSTITUTION:When it is necessary to correct the contents of the ROM2, the contents of the ROM2 are equivalently corrected by a memory adding/correcting means 10. Namely, correcting information for a main memory 3 is read from an I/O device 8 through an I/O interface 7 to correct the contents of the main memory so that system operation is not influenced. Consequently, the correcting information can be written in a memory 5 backed up by power supply using a battery. If the correction of the contents of the ROM2 is urgently required, the correcting information is inputted to the memory 5 and then erased from the memory 5, so that the memory can be patched in accordance with the using status of the system.

Description

[Detailed Description of the Invention] Industrial Application Field The present invention is applicable to a read-only memory that stores programs or data of a processor, corrects design errors in programs or data, corrects bit garbled bits due to defects, and functions. FIG. 1 shows the configuration of a conventional example of an addition/modification device for modifying a part of the system for the purpose of adding or changing a part of the system. In FIG. 1, a processor 1 is configured to execute a program in a semiconductor masked read-only memory 2 and access a random access memory 3 through a bus 4. By the way, in such a configuration, if it is necessary to make some kind of modification to the masked read-only memory 2, it is necessary to recreate the masked read-only memory 2 and replace it. It was extremely inconvenient, requiring a lot of expense and effort.

Purpose of the Invention The present invention eliminates the above-mentioned problems of the conventional method, and eliminates factors such as program design errors, bit errors due to defects, and partial additions and modifications of functions to the contents of non-rewritable read-only memory. The object of the present invention is to provide an excellent addition/modification device that can easily modify or add the contents of a read-only memory, which is equivalently non-rewritable, even if the contents change. .

Structure of the Invention In order to achieve the above object, the present invention first transfers the contents of a non-rewritable read-only memory to a rewritable random-access memory, and then modifies and adds the contents of this random-access memory to the read-only memory. The information is stored together and is configured to be additionally modified based on the contents of another additional/modified information memory.

Description of examples FIG. 2 shows the configuration of an embodiment of the present invention.

In FIG. 2, 1 is a processor, and 2 is a memory that stores programs executed by the processor 1. 3
is a random access main memory memory 1c accessed by the processor 1; 4 is a bus; 5 is a read/write random access memory that can be saved during power outage; in this embodiment, it is a semiconductor random access memory backed up by a battery; using memory. 6 is a read-only memory, and in this embodiment, an erasable programmable read-only memory (EPR, OM) is used.

In addition, random access memory 5, read-only memory 6
In both cases, the correction data of the memory contents of the main memory 3 is stored in the format as shown in FIG.
The data is stored in the order of yte number and modified data. and,
Processor 1 connects each memory 2.3.5 via bus 4.
．． 6. The read-only memory 2 still stores a program loading means 9 and a memory addition/modification means 10 that operate according to the flowcharts shown in FIGS. 4 and 5, which will be described later. It is configured so that it can be accessed by the processor 1 as a memory.

In the embodiment described above, when the power is turned on or the system is reset, the processor 1 detects this and executes the program loading means 9 in the read-only memory 2. That is, as shown in FIG. 4, the contents of the read-only memory 2 are loaded into the main memory 3 of the random access memory in 5 tepl, and
Main memory 3 from read-only memory 6 at 5tep2
In step 3, the content of the main memory 3 is corrected, and in step 3, the correction information for the main memory 3 is extracted from the Ndam Access Memory 5 with battery power backup, and the content is stored in the main memory 3. Make corrections.

On the other hand, if it is necessary to modify read-only memory 2,
Either the read-only memory 6 is replaced and the PL is performed again, or the read-only memory 2 can be equivalently modified by the memory addition/modification means 10 using the input/output device 8 as shown in FIG. In other words, 5 tepl in Figure 5
In step 2, correction information for the main memory 3 is read from the input/output device 8 via the input/output interface circuit 7 so as not to affect system operation.
If the contents are corrected, the correction information can be written in the memory 5 with battery power backup in step 5. Therefore, if it becomes necessary to urgently modify the read-only memory 2, it is sufficient to equivalently modify the latter, that is, according to the flowchart of FIG. 5, and then permanently modify it at a later date. That is, in this case, it is possible to patch the memory according to the operational status of the system, such as by putting the correction information into the backup memory 5 and erasing the same information from the memory 5.

In addition to the effects of the invention, as is clear from the embodiments, the additional modification device of the present invention can prevent read-only memories that have been manufactured in large quantities from becoming necessary to make additional modifications to their contents due to program bugs or other causes. Even if a bug occurs in the program, it can be fixed equivalently, so ■ The time and cost of remanufacturing read-only memory can be greatly reduced ■ Even if a program bug or correction occurs, it can be fixed. As a result, manufacturing of read-only memory can be started at an early stage, equipment testing time and manufacturing shipment can be shortened, and even if bit corruption occurs in read-only memory, it can be fully dealt with. has advantages.

[Brief explanation of the drawing]

Fig. 1 is a schematic block diagram showing a conventional configuration, Fig. 2 is a schematic block diagram of an embodiment of the isometric content addition/modification device of the present invention, and Fig. 3 is a random access with power backup used in the same embodiment. An explanatory diagram showing the internal structure of the memory, an erasable program read-only memory, and FIGS. 4 and 5 are flowcharts showing the operation of the main parts of the same embodiment. ... Read-only memory, 3 ... Random access memory that can be read and written 1c4 ... Bus, 5 ... Random access memory with battery power backup,
6... Erasable program read only memory, 7... Input/output interface circuit, 8...
- Input/output device, 9...Program loading means,
10...Memory addition/correction means. Name of agent: Patent attorney Toshio Nakao and one other person Figure 1 Figure 2 Figure 4 Figure 5

Claims (1)

[Claims] a read-only memory storing a program or data of a processor; a readable/writable random access main memory for loading the contents of the read-only memory; and error correction of the program or data stored in the read-only memory; Additional modification information memory, such as a read-only memory that stores additional modification information for the purpose of bit error correction and partial functional addition modification, and a readable/writable random access memory that can be saved during a power outage, and the contents of the read-only memory described above. Addition of equivalent content to a read-only memory comprising loading means for loading into the main memory, and means for reading the contents of the additional modification information memory and additionally modifying the contents of the main memory based on this. Correction device.