JPH03102426A - Rom control system using address conversion mechanism - Google Patents

Abstract

PURPOSE:To easily change and add the functions of a ROM program with no exchange of ROMs by rewriting a table to give an access to a virtual ROM via an address conversion mechanism when an access is given to a ROM. CONSTITUTION:A ROM program 1-1 is loaded to a ROM 1 which is assigned to a fixed address and simultaneously a ROM program undergone the change and addition of functions is loaded to the virtual ROM 2-1 of a RAM 2 from an auxiliary storage at an early stage of the start. Meanwhile a table is rewritten so that an address conversion mechanism 3 has an access to be given to the ROM 1 to the ROM 2-1. Hereafter the access is given to the ROM 2-1 of the RAM 2 for the execution of a due process. Thus, the functions of the program 1-1 can be easily changed and added with no exchange of the ROM 1.

Description

[Detailed Description of the Invention] [Summary] Regarding a ROM control method that changes or adds functions to a ROM program using an address conversion mechanism, the RA
A ROM program with changed or added functions is loaded into the virtual ROM on M, and the table of the address translation mechanism is rewritten, and the virtual ROM is then accessed and processed to change or add functions to the ROM program without replacing the ROM.
For the purpose of easy addition, there is a ROM in which system programs of a computer system are assigned to fixed addresses and implemented, a RAM for storing data and programs, and a memory access from the computer system. Equipped with an address conversion mechanism that performs address conversion in response to requests and accesses the above ROM or virtual ROM in RAM, and at the time of startup, it is written from the 6 auxiliary storage devices to the virtual ROM on the RAM to change or add functions. At the same time as loading the above ROM program, rewrite the table so that the address translation mechanism accesses the virtual ROM when accessing the ROM, and configure the address translation mechanism to access the virtual ROM on the RAM and perform processing thereafter. .

[Industrial application field]

The present invention relates to a ROM control system that changes or adds functions to a ROM program using an address translation mechanism ζ. In many electronic meters, essential software such as system startup programs are built into the hardware in the form of ROM and shipped. Even if the system uses virtual addressing, this ROM program is usually located and used in a virtual address space. However, −
It is common for software to be revised for hardware (including firmware) that is unlikely to change once shipped, and the ROM program may lack functionality for the new software.
It is desired to change the Mb[:z-gram as necessary.

[Prior art and the problem to be solved by the invention] Conventionally, when it becomes necessary to change or add functions to an essential ROM program such as a startup program for a computer system, the ROM itself and the hardware containing it are There was no other option but to replace it with a new one. For this reason, there is a problem in that replacing parts of a system that has already been shipped is a costly task in terms of cost and time.

The present invention changes the function to the virtual ROM on RAM at startup.
The purpose is to load the added ROM program, rewrite the table of the address conversion mechanism, and then access and process the virtual ROM, making it easy to change and add functions to the ROM program without replacing the ROM. .

Means to solve problem C] Means for solving the problem will be explained with reference to FIG.

In FIG. 1, ROML is a read-only memory in which system programs of an electronic computer system (ROM program 1-↓) are assigned to fixed addresses.

The RAM 2 is a readable and writable memory that stores data, programs, and the like.

The address translation mechanism 3 performs address translation in response to a memory access request from the computer system, and converts the address into a ROM.
This is to access the I or the virtual R○M2-1 on the RAM2.

As shown in FIG. 1, the present invention implements a ROM program 1-1 such as a system program of a computer system in ROM1 assigned to a fixed address, and transfers it from an auxiliary storage device to a virtual ROM2 on RAM2 at the time of startup. R.-1 with functional changes and additions. When the OM program is low 1', the ROMI is sent to the C address conversion mechanism 3.
The table is rewritten so that the access to the R. A M 27 virtual ROM 2-{ is accessed to perform processing.

Therefore, at startup, the ROM program with changed or added functions is loaded into the virtual ROM 2) on RAMZ, and the table of the address translation mechanism 3 is rewritten.
By accessing OM2-1 and performing processing, RO
It becomes possible to easily change or add functions to the ROM program 1-1 without replacing the MI.

〔Example〕

[Operation] Next, the structure and operation of one embodiment of the present invention will be explained in detail using FIGS. 1 and 2.

In FIG. 1, an address translation mechanism 3 performs address translation in response to a memory access request from an electronic computer system, and converts addresses into ROMI or virtual ROM on RAM 2.
Address management table 3-1 is a table that converts the address requested for memory access into the physical address to be actually accessed.
1, and an address management section 3-2 that manages this address management table 3-1.

The memory access mechanism 4 receives memory access requests from the CPU 5, etc., and sends them via the address translation mechanism 3.
The virtual ROM 2-1 or ROM 1 on AM2 is accessed.

CPU5 is ROMI! Various processes are performed in accordance with the stored ROM program kl or the ROM program with modified or added functions stored in the virtual ROM 2-1 of the RAM 2J.

The auxiliary storage device 6 is an external storage device such as a floppy disk device, and stores ROM programs with modified or added functions in the RA. This is for loading into the virtual ROM 2 of M2J2.

Next, the operation of wj in FIG. 1 will be explained in detail using FIG.

FIG. 2(A) shows the initialization procedure of the system.

In FIG. 2(A), (2) indicates that the IPL ROM initializes the system. This uses the ROM program 1-1 shown in FIG. 1 R○M1 to perform various initial settings of the system.

(2) loads the boot loader from the auxiliary storage device 6 onto the RAM 2;

■The bootloader initializes the system.

This is 0 and the auxiliary {. ! The bootloader loaded onto the RAM 2 from the y device 6 initializes the system.

■ is the R program for the virtual ROM from the auxiliary storage device 6.
Load on AM. This is the RA from the auxiliary storage device 6.
Load a new ROM program [1 gram] with changed functions and additions to virtual ROM 2-1 on the MZ.

(2) requests the address management section 3-2 to transfer the portion of the address management table 3-1 indicating ROMI to the RAM.
Rewrite to indicate virtual ROM2-1 on Z. As a result, when the CPU 5 accesses the ROM 2-1, the address management table 3-1 allows the virtual ROM 2--
The address is converted to access 1.

[Phase] is R A
Load into M2.

The new RO whose functions have been changed and added by the process described in 2.
Load the M program into the virtual ROM2) on RAMZ, rewrite the address management table 31, and load it into the ROM.
A setting is made so that an access to i is converted into an address to access temporary fiROM 1-1 on RAMz.

FIG. 2(0) shows the ROM access procedure.

In FIG. 2(b), the memory access mechanism 4 receives access in (2).

If 0, the corresponding {reflection)' address is converted into a physical address according to the data in address table 3-1.

O accesses memory (virtual ROM 2-1 on RAMZ, etc.) using a physical address.

By the above processing, virtual ROM2-1 of RAM2J2
By accessing and processing the ROM program of ROMI or virtual ROM2-1, the software can access and process the ROM program of ROMI or virtual ROM2-1 without being aware of the changed or added ROM program. It becomes possible to do so.

〔Effect of the invention〕

As explained above, according to the present invention, a ROM program with modified or added functions is loaded from the auxiliary storage device to the virtual ROM 2-1 on the RAM 2, and the address management table 3-1 of the built-in address conversion mechanism 3 is loaded. Since we have adopted a configuration in which the virtual ROM 2-1 is accessed and processed after rewriting, it is possible to easily change or add functions to the ROM program without replacing the ROMI, and the software can be changed without changing the ROM program. Processing can be performed without being aware of what has been done.

[Brief explanation of drawings]

FIG. 1 shows the configuration of one embodiment of the present invention, and FIG. 2 shows a flowchart explaining the operation of the present invention. In the figure, l is ROM, 11 is ROM program, 2 is RA
M, 2-1 is a virtual ROM, 3 is an address translation mechanism, 3-
Above is the address management table, 32 is the address management section, 4
5 represents a memory access mechanism, 5 represents a CPU, and 6 represents an auxiliary storage device.

Claims (1)

[Claims] In a ROM control method that changes or adds functions to a ROM program using an address conversion mechanism, a ROM (1) in which a system program of a computer system, etc. is assigned to a fixed address and mounted; RAM (2) that stores programs, etc., and ROM (1) or RAM that performs address conversion in response to memory access requests from electronic computer systems.
(2) An address translation mechanism (3) that accesses the virtual ROM (2-1) above, and the virtual RO on the RAM (2) is transferred from the auxiliary storage device at the beginning of startup.
A ROM program with modified or added functions is loaded into M (2-1), and the address translation mechanism (3
) when accessing ROM (1), the virtual ROM
Rewrite the table to access (2-1),
A ROM control system using an address translation mechanism, characterized in that the virtual ROM (2-1) on the RAM (2) is subsequently accessed to perform processing.