JPH02228732A - Electronic computer - Google Patents

Abstract

PURPOSE:To obtain an electronic computer which has both high reliability against radiation and system flexibility by providing a command program, a software initializing program, a parity check program, and a program in which a subroutine group, a scheduler program etc., are built. CONSTITUTION:A command program 9 to control data input/output between the electronic computer and the external is stored in a data read-only memory 2, and a software initializing program 7 to write data in a data readable/ writable memory 3 is stored there also. Further, a parity check program for memory data check of this memory 3 is stored in the memory 2. A subroutine program group 11 and the scheduler program 10 which successively calls subroutine programs are stored in the memory 3. Thus, a sufficient safety against radiation is secured and the system flexibility is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a computer mounted on, for example, an artificial satellite, a spacecraft, a space base, etc.

[Conventional technology]

Conventional electronic computers can be broadly classified into two types. FIG. 3 shows a typical configuration of the first type of RAM-based computer (for example, O, J.

Theis, ” 5pacecraft Comput
ters: 5tate-of-1he-Art
5urvey, ” IEEE Trans, on
Computers.

I), 85-97. (1) is a block diagram showing the central processing unit (Apr, 1983).
(hereinafter abbreviated as CPU), +21 is read-only memory (
(hereinafter abbreviated as ROM).

(31 is read/write memory (hereinafter abbreviated as RAM)
# (41 is a bus (data bus, address bus It U
``MJ a /<
The work area on the AM (including the stack area), ■ is the spare area on the RAM.6 Although not shown in the figure, there is also an I10 interface as a source, clock
(An external clock may be used in some cases), a DMA controller, an interrupt processing circuit, a safety circuit, etc. are often added, but these are omitted here because they are not directly related to the present invention.

Figure 4 shows ROM, the second type of conventional electronic computer.
Typical configuration of the main computer (e.g.

Intermediate use and others [Development of satellite onboard computer (OBC)] Part 2
In Figure 91, (1) is the CPU, and I2+ is the RO.
M, 131 is RAM, (41 is bus, C5) is R
The installed program stored in the OM, (6) is a work area (including a stack area) on RAM, and (2) is a spare area on RAM.

Next, the operation of these electronic computers will be explained.

The installed program stored in the ROM +2+ or RAM f31 is sequentially read out by the CPU (11) via the server (4).

It is decoded and processed to perform various functions required of electronic computers, such as input/output data processing, control calculations, and failure detection. At this time, the work area (6) on the RAM is used as a storage area for variable parameters and intermediate data, and as a stack evacuation area.
It is used as appropriate under the control of PU (1).

[Problem to be solved by the invention]

Among conventional electronic computers, the first type of RAM-based computer is capable of rewriting on-board programs stored in RAM in orbit based on commands from the ground, or patching on-board programs using spare areas. . So-called in-orbit reprogramming was possible. Therefore, it was possible to flexibly deal with any problems that may occur in orbit. On the other hand, many of the semiconductor devices currently used as RAM for space applications are vulnerable to radiation, and have the major drawback of often causing so-called single event errors in which the bit status is reversed in orbit. Friend, radiation shielding measures are required for this reason, but to be sure that complete prevention is impossible, many of these types of computers store critical programs and parameters in a very safe ROM, so that they can be protected in the event of an error. Measures were taken such as temporarily evacuating to a safe mode using the program on ROM and then reloading the program to RAM. But during this time.

- Just in case it is unavoidable to stop the mission, albeit temporarily. To avoid such problems, there is a method of using an error correction code (FCC), but this method has the drawback of increasing memory and processing circuitry.

On the other hand, in the second type of computer, which is based on ROM, the energy level required to flip bits in ROM is much higher than that in RAM, so single event errors caused by radiation are not a problem, and reliability is high in this respect. It was characterized by its high price. However, all installed programs are R
Since it is written in the OM, in-orbit reprogramming is generally impossible, and there is a drawback that it is not possible to respond flexibly to unexpected malfunctions in orbit.

This invention was made to solve the above-mentioned problems in conventional electronic computers, and has the high reliability against radiation that conventional ROM-based computers have,
The object of the present invention is to obtain an electronic computer that has system flexibility due to the in-orbit reprogramming function of a RAM-based computer without adding any special hardware.

[Means to solve the problem]

The computer according to the present invention includes a program for controlling data input/output to/from the outside of the computer (hereinafter referred to as a command program) and a program for loading a program onto the RAM (hereinafter referred to as a software initialization program). and a program to check the parity of RAM memory (see below).

A memory area is provided on the ROM that can store a parity check program (referred to as a parity check program), and a group of modularized subroutine programs (for example, grouped by processing function) is provided on the RAM.

It is provided with a memory area that can store programs in which a scheduler program and the like that control the processing of subroutine programs are embedded.

[Effect]

The electronic computer in this invention has a command program i
The command program is stored in the ROM, and when an abnormality occurs in the RAM memory, the processing of the command program is executed preferentially, so that the communication means between the ground station and the satellite is sufficiently protected against radiation encountered in outer space. In addition to ensuring safety, on-board programmable programs that may need to be changed in orbit can be stored in RAM, making it possible to reprogram them in orbit.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

In Figure 1, (1 is CPU, +2) #iRoM,
[31 is RAM.

(4) is the path, (5) is the ROM121. and RAM+3
(6) is a work area on RAM, (71 is a software initial setting program stored in ROM (2).

(8) is the same (parity check program stored on ROM +21, (9) is the same (command program stored on ROM (21), αω is the scheduler program in the program loaded on RAM, aυ
is a group of modularized subroutine programs in a program that is not loaded onto the same RAM.

Next, the operation of this embodiment will be explained.

The programs stored in the ROM12+ and RAM+31 are sequentially read, decoded, and processed by the CPU (11) via the bus (4).The work area (6) on the RAM13+ is.

It is used as a storage area for variable parameters and intermediate data, a stack area, etc. under the control of the CPU.

The subroutine program group (lit) of the installed programs are all executed under the scheduler program 01.

The software initialization program (7) is executed when it is determined to be necessary immediately after the loading program starts processing. Through this process, the scheduler program αα and the modularized subroutine program group I perform a process of writing data from the ground station onto the RAM.

Thereafter, control is transferred to the parity check program (8) on the ROM.

In the parity check program (8), the RAM
Divide the memory on +31 into multiple unit memories.

Perform a parity check. At this time, if a parity check error occurs, processing control is transferred to command program (9)K on ROM (2). command blockrum (
9) is the RAM where a parity check error occurred at the ground station.
The address range of the unit memory of the memory is notified, and a program that does not cause a parity check error is written in the unit memory of the RAM memory based on data from the ground station. Also.

When a parity check error occurs, subsequent processing of the scheduler program αα proceeds.

When the processing of the scheduler program al is completed, control of the processing is given to the command program (9) on the ROM+21, and data communication processing with the ground station during normal operation is performed.

Note that a subroutine call instruction in the scheduler program αυ calls a specified subroutine program and processes the subroutine block.

At this time, if a part of the unit memory with a parity check in the RAM memory starts to be rewritten due to commands or other traps from the ground, a parity check error occurs in the processing of the parity check program (8), and the program in the RAM + 31 memory is transferred to the ground station. Processing of the command program (9) is prioritized in the trench where the unit memory is completely rewritten with data from the unit.

FIG. 2 shows the software initialization program (7) after the installed program in the above embodiment starts execution.
and then run the parity check program (8)
After processing the command program (9), or executing the subroutine call instruction in the SFJ program α0, the subroutine program executes the process, and the process of command progera A +91 is executed.PjA 2 is a flowchart explaining in detail. (5)
~all are the same as in FIG. na is RAM+3
1 memory work area (this is the divided unit memory of the memory other than 61).

In the figure, immediately after the execution of the onboard program starts (13), it is determined that it is necessary by α4, for example, due to flag change in the work area (6), and the software initialization program 7 (61 processing will be implemented.

As a result, the scheduler program a1° and the subroutine program group (11+) are written into the RAM +31 using the data from the ground station.

Thereafter, a parity check program (8) is executed to perform a parity check on the RAM memories (12a), (1zb), . . . which are divided into a plurality of unit memories. Result 1 For example, unit memory (
When a parity check error occurs in 12a), the processing is controlled by the command program (91
Move to (arrow (15a)), i. When no parity check error occurs, processing control is transferred to the scheduler program αG on RAM (2) (arrow (1sb)
).

Command program (In the process of 91, a parity check error occurred in the ground station. Unit memo of RAM memory!
J (12a) and uses the data from the ground station to update the unit memory (t2) of its RAM memory
a) Write a program that does not cause an lc parity check error.

No parity check error occurs and the subroutine call instruction (16
a) When K is encountered, process arrow α7+) which calls subroutine (11a). Scheduler program α
When the processing of
:Ivn)'7'O/5mu(911c$D (arrow us).

Data communication processing with the ground station during normal operation is performed.

At this time, commands from the ground are busy, for example.

If a part of a certain unit memory (12b) on RAM +31 has been rewritten, a parity check error will occur in the processing of the parity check program (8), and the processing control will be changed until the unit memory (12b) on RAM +31 is completely rewritten. Priority is given to the processing of the command program (9) until it is rewritten.

As described above, the installed programs are executed sequentially.
Reprogramming on the orbit is realized by rewriting the data on the RAM memory.

When the processing of all installed programs is completed 119.

Execution of a series of installed programs is started again at an appropriate timing under the control of the CPU (11).

Note that the in-orbit reprogramming function achieved by the above embodiment can be used not only in orbit but also for purposes such as inserting diagnostic programs in ground tests, and can be used to improve test efficiency and quality. Great effects can be expected.

〔Effect of the invention〕

As described above, according to the present invention, a command program is stored in a ROM in an electronic computer, and when an abnormality occurs in the RAM memory, processing of the command program is carried out preferentially, so that the command program can be executed at a ground station. In addition to ensuring sufficient safety against the radiation encountered in outer space, the main onboard programs can be reprogrammed in orbit by storing them in the RAM. This has the effect of significantly increasing flexibility.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing an electronic computer according to an embodiment of the present invention, FIG. 2 is a flowchart showing details of the operation according to an embodiment of the present invention, and FIGS. 3 and 4 are representative of conventional electronic computers. FIG. 2 is a configuration diagram showing two types. In Figure 1 (11 is CPU, +21 is ROM,
43+ is RAM. (4) is the bus, (5) is the onboard program, (61 is the RA
Work area on M, (7) is software initial setting program, (8) is parity check program, (9
) is a command program, αυ is a scheduler program r1Ll is a group of modularized subroutine programs, αti is a subroutine call instruction, 12Lji
;t, it is a spare area. Moreover, in FIGS. 1 to 4, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] In an electronic computer configured with a central processing unit that controls processing, a data read-only memory, and a data readable/writable memory, there is a memory that is connected to the outside of the computer in the data read-only memory. A memory area that can store a program that controls data input/output, a memory area that can store a program that writes data on the data read/write memory, and a memory area that can store a program that writes data on the data read/write memory. A memory area that can store a program for checking memory data, and a memory area that can store a group of subroutine programs in the memory that can read and write data, and a schedule for sequentially calling these subroutine programs. An electronic computer equipped with a memory area capable of storing Eura programs.