JPH03214324A - Computer system - Google Patents

Abstract

PURPOSE:To eliminate the need of extending a memory area for a program whose residence is not required by loading a menu program by an overlay method in a store area of a Basic Input Output System which is made resident originally and using it. CONSTITUTION:ROMs 203, 301, and a RAM 302 constitute a first memory and a second memory, respectively, and all programs in the ROM 203, and a menu program in the ROM 301 constitute a first program and a second program, respectively. In such a state, after a first program is written in a second memory 302 of a high speed, it is made resident by inhibiting write fundamentally and the processing is executed, and also, at the time of necessity, the writing inhibition is released and a second program is overwritten in a first program. Accordingly, a necessary part of a first program can be used by a second program. In such a way, it becomes unnecessary to extend a memory area for a second program being non-resident originally of the capacity of a second memory 302.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a computer system such as a personal computer.

[Conventional technology]

In conventional computers, BIO
S (Basic input output
Basic control software called ``stem'' is written into the ROM, and the BIOS is used to perform processing.

However, since the BIOS is stored in ROM, C
It takes a long time for the PU to access, for example, the access time of RAM is several tens of nanoseconds or less, whereas the access time of ROM is over 100 nanoseconds, which becomes a problem when trying to increase the speed. was.

Therefore, conventionally, as a memory configuration of a personal computer, the BIO is stored during system operation as shown in FIG.
A RAM 102 is provided to store the BIOS stored in ROMI 0 1 when the system is started up.
I am trying to load M102. And this R
With AM102 write-protected, B in RAM102
Processing was performed using IOS to speed up the processing. Note that the RAM 103 is a storage area for user programs, and is not write-protected.

[Problem to be solved by the invention]

However, due to the diversification of user requirements in recent years, it has become difficult to perform system startup processing after running a menu program for setting a dispersion switch that defines the system environment when starting up a system. be exposed. This menu program is a program that uses the required parts of the BIOS, so the BIOS
It is necessary to coexist with However, in conventional personal computers, as explained using FIG.
After S is written to the RAM 102, writing is prohibited, so coexistence of the BIOS and menu program cannot be achieved except by increasing the capacity of the RAM 102. However, in addition to the problem of having to increase the memory capacity when doing this, memory space is reserved for menu programs that do not originally need to be resident (they only need to exist at system startup, etc.). In terms of
The problem was that it was inefficient.

Another method is to load the menu program into the RAM 103, but in this case, the system program and application program will be overwritten, making it impossible to start up the system with the system program and application program remaining. It was put away.

Therefore, it is an object of the present invention to provide a computer system in which there is no need to expand a memory area for a program that does not need to be made resident, and in addition, it is possible to use a necessary part of a program that is originally made to be resident from this program. With the goal.

[Means to solve the problem]

The computer system according to the present invention includes a first program that is not writable and stores a first program and a second program.
and a second memory that has a smaller capacity than the first memory, can be accessed at a higher speed than the first memory, and can be read and written, and the second memory can read and write the first program when necessary. is loaded into a second memory, and then the second memory is write-protected and processing is performed using the first program in the second memory, and when a predetermined condition is met, the second memory is read-protected. Release the write protection of the memory, overwrite a second program in a predetermined area of this second memory, execute the second program, and then overwrite the first program again in the predetermined area after execution is completed. The feature is that the erased portion is loaded and write-protected.

[Effect]

Since the computer system according to the present invention is configured as described above, the first program that should originally be resident is loaded into the second memory and is accessed and used at high speed while being write-protected and protected. At the same time, when necessary, the write protection is canceled and the first program is overwritten with the second program, so that the second program can use the required part of the first program. Further, the original state is returned upon completion of execution of the second program, and the residency and protection of the first program can be realized while employing an overlay method.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS A computer system according to an embodiment of the present invention will be described below with reference to FIGS. 1 to 9 of the accompanying drawings.

FIG. 2 shows a personal computer system according to an embodiment of the present invention, in which a personal computer centered on a CPU 201 is connected to a large number of peripheral devices. The CPU 201 is connected via a bus 202 to a ROM 203 in which the BIOS is stored, and a RAM 20 which is a user memory.
4. VRAM 20 where display text is stored 5. RAM 206 where graphic data is stored, interrupt controller 207, calendar clock 208, serial communication interface 209, printer interface 210, floppy disk controller (FDC)
) 211, timer 212, interface 213 for cassette streamer (stream type magnetic tape device)
, Graph Inok display controller 214, 21
5. A DMA controller 216, a keyboard interface 217, and a mouse interface 218 are connected. A communication device such as a modem is connected to the interface 209, a printer 220 is connected to the interface 210, and a floppy disk controller 2 is connected to the interface 209.
A floppy disk device 221 is connected to 11, and a buzzer 222 is connected to timer 212. Furthermore,
A cassette streamer 223 is connected to the interface 213, and a graphic display controller 214
A CRT display device 224 is connected to the , a keyboard input device 225 is connected to the interface 217 , and a mouse 226 is connected to the interface 218 . Furthermore, three slots 227 for internal expansion and four slots for external expansion are connected to the bus 202. For example, it shows that a hard disk device 229 can be connected to one of the slots 227 via a hard disk controller 228.

In addition, the CPU 201 has N P
Processor Extension) 2 3
It is possible to expand functionality (enhance numerical calculation functions) by connecting 0.

The CUO 201 of the personal computer system configured as described above is provided with a main memory consisting of a ROM and a RAM, and a control program including each means described later for executing the operations shown in the flowchart of FIG. , for example, stored in R OM.

On the other hand, the memory configuration of the memory in which the programs loaded and the user programs are stored in this embodiment is as shown in FIG.

That is, the ROM 301 in the main memory and the RA in the main memory
M302, BIOS-ROM203 and VRA in Figure 2
It consists of an M205 and a RAM 204 which is a user memory. R O M 2 0 3 has BIOS (1) and R
OM20 3 program. Data RAM3 0 2
A program P1 to be loaded and BIOS(n) are stored. The program in the area (a) of the BIOS (II) is a program to be reloaded. The ROM 301 stores a menu program (b) for setting date switches and memory switches that define the system environment. When the menu program (b) is stored in the RAM 302 in place of the program for the area indicated by (a) in the BIOS (n), it becomes a program that is integrated with the BIOS and performs processing using the BIOS. It is a swappable program. On the other hand, the RAM 302 and VRAM 205 are empty areas immediately after the power-on reset.

Furthermore, a user program may be stored in the RAM 204 at the time of reset. Furthermore, the capacity of the RAM 302 is configured to be equal to the capacity of the ROM 203.

In the above configuration, the ROMs 203 and 301 constitute the first memory, the RAM 302 constitutes the second memory, and the ROM2
All programs in 03 are the first program, ROM30
The menu program in 1 is the second program.

Next, the management of the memory according to an embodiment of the present invention will be explained with reference to the flowchart of FIG.

First, by powering on the system or resetting the main unit or keyboard input device 225 (RESET).
In response to a command by key operation, the power-on reset state (memory state in FIG. 3) A is entered. Then, the control program creates a checksum to check for data errors in the ROM 203, compares it with the checksum result created in advance (Sl), and detects whether or not there is an error (
S2). If an error occurs here, data is given to the graphic display controller 214 to cause the CRT display device 224 to display the error, and the timer 212 causes the buzzer 222 to emit a warning sound.
p) and enters a halt (HLT) state, waiting for operator intervention (S3).

On the other hand, if the checksum result does not result in an error, V
After testing whether the RAM can write and read data normally (S4'), since the data is normal, program P1 in the ROM 203 is transferred to the VRAM.
205 (S4). The memory configuration in this text load state B is shown in FIG. As a result, the graphic display controller 214
The data of R A Fw1 2 0 5 is displayed in text on the CRT display device 224 (S5). Next, the control program is RO~120
In order to switch between RAM 3 and RAM 302,
02 and checks whether data can be written and read normally using, for example, test data (S6). Then, it is determined whether or not the operation was performed normally (S7), and if the operation was not performed normally, the graphic display controller 2
14 to cause the CRT display device 224 to display an error, and to generate a warning sound from the buzzer 222 via the timer 212 (S8).

On the other hand, if data is normally written and read from RAM 302, the program P1 will contain the data (BIOS (1), program P1, BIOS
(II) to RAM303 (S9), and this R
AM303 can be read, but written is prohibited and protected (S10). This protection method is based on, for example, a boundary register method in which the upper and lower limits of write prohibition are regulated using boundary registers.

As mentioned above, the control program is stored in RAM: 302 after the bow-on reset (including reset key operation).
It functions as a loading means for loading the ROM203 program into the memory and prohibiting writing. The initial load state C in which the memory is configured in this manner is shown in FIG.

Next, the control program jumps to a predetermined address in the RAM 302 (Sll), proceeds to processing using the program in the RAM 302 (S12), and includes a predetermined input determination from the keyboard input device 225 described below. Menu execution judgment letter! ! Proceed to D. Specifically, for example, by using a timer interrupt, data is fetched from the keyboard input device 225 at predetermined time intervals (31B), and the process of detecting the presence or absence of data (S14) is repeated until the data does not become present. In some cases, 10,000 times (
(predetermined times) (S 1 5). Here, if data is present, it is detected whether or not both the control key (CTRL key) and the graphic key (GRPH) for sending a command to proceed to overlay state E have been operated (S16). Here, if both keys are not operated, the process advances to step S15. The memory configuration in such a menu execution determination state D is shown in FIG.

On the other hand, if it is detected in step S16 that both keys have been operated, the control program cancels the protection (write prohibition) of the RAM 302 and allows data to be written in the RAM 302 (S17). In this manner, the control program functions as a release means that monitors whether the predetermined condition is satisfied and releases the write protection of the second memory when the predetermined condition is satisfied.

Next, the control program overwrites the menu program (b) in the ROM 301 with the program in the area (a) of the BIOS (n) in the RAM 302 (S18), Jump to the specified address of the loaded menu program (
S19), transition to execution of the menu program (
S20).

This menu program (6) is displayed on the display device 22.
4 to display menu selection items, keyboard 225
This menu program (b) uses the same RAM 30 as it is a program that manually sets items using keys from
Processing can proceed using the BIOS in 2 (by calling subroutines). The memory configuration when the overlay EilE is executed in this way is shown in FIG.

Further, FIG. 8 shows the memory configuration when the menu program is in the execution state F. Thus, the control program functions as an overlay means for implementing an overlay scheme.

Next, when the control program detects the end of the menu program, the BIOS (II) in the ROM 203 (
The program in the area indicated by a) is reloaded into the corresponding area in the RAM 302 (the area where the menu program (b) is stored) (S21), and the RAM 302 is protected against data writing (S22). In this way, the control program functions as a reloading means for reloading erased programs. The memory configuration in reload state G when reloaded is shown in FIG. After reloading, the memory configuration returns to the state shown in FIG.

If step S22 ends in this way, or if the predetermined data is not input despite checking step S15 10,000 times, V
The RAM 205 is cleared to invalidate the program P1, and the display on the CRT display device 224 is also cleared (3 2 3), and the process proceeds to system startup processing.

As described above, in this embodiment, B
By loading and using the menu program in the IOS storage area using an overlay method, memory can be used effectively, and RAM can be protected as appropriate.
It is also possible to prevent the system from operating abnormally due to the BIOS being illegally rewritten.

The present invention is not limited to the above embodiments, and various modifications are possible.

For example, the types of programs are not limited to BIOS and menu programs, and any program having similar characteristics will work effectively. Further, the condition for proceeding to the overlay state may be determined by operating another key, or may be automatically satisfied after a predetermined period of time. Furthermore, the configuration of the ROM and RAM is not limited to one chip, but may be one that can be placed in either read/write mode at the same time as one module. Alternatively, writing may be enabled when the second program is loaded into the second memory, and the write prohibition may be canceled upon completion of execution of the program.

〔Effect of the invention〕

As described above in detail, according to the present invention, after writing the first program to the high-speed second memory, the first program is basically made to reside as a write-protected memory to perform processing.
Moreover, when necessary, the write protection is canceled and the second program overwrites the first program.
The second program can use necessary parts of the first program. Therefore, the capacity of the second memory is
This has the advantage that the second memory can be used efficiently without having to expand it for a second program that is non-resident in nature.

[Brief explanation of drawings]

FIG. 1 is a flow chart showing the operation of a personal computer system according to an embodiment of the present invention, FIG. 2 is a block diagram of a personal computer system according to an embodiment of the present invention, and FIGS. FIG. 10 is a diagram showing a memory map transitioned according to an embodiment of the present invention, and FIG. 10 is a diagram showing a transition of memory contents according to a conventional example. 201...CPU, 20B...ROM, 204...
・RAM, 25...VRAM, 206...RA
M, 230...NPX, 301...ROM, 30
2...RAM0

Claims (1)

[Claims] a non-writable first memory in which a first program and a second program are stored; and a second memory that is readable and writable, and after loading the first program into the second memory when necessary, the second memory is write-protected and the first program in the second memory is loaded. In a computer system that performs processing using
When a predetermined condition is satisfied, the write protection of the second memory is canceled, the second program is overwritten in a predetermined area of the second memory, the second program is executed, and after the execution is completed, A computer system characterized in that a portion of the first program erased by the overwriting is loaded again into the predetermined area to prohibit writing.