JPS6225367A - Computer system - Google Patents

Abstract

PURPOSE:To easily rewrite an execution program at need by providing a readable/rewritable memory part in a subsystem and also providing a disconnection part which disconnects a central processing part from an internal bus line. CONSTITUTION:When the program is modified, a bus switching control part 11 controls a central processing switching part 8 on the basis of a command signal from the 1st central processing part 1 to disconnect the 2nd central processing part 4 from the internal bus line 6 and also controls a bus switching part 10 to switch the connection of the readable/writable memory part 9 from the line 6 to an external bus line 3. In this state, a new execution program is written in the memory part 9 from the processing part 1 through a line 3. The control part 11 connects the processing part 4 to the line 6 after the writing and the memory part 9 is switched to the line 6 to execute the program written on the memory part 9.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention has a first central processing unit that manages the entire system and a second central processing unit, each of which implements a part of the function. This relates to a computer system in which a plurality of subsystems are connected by external signal lines.

(Prior Art) Fig. 2 shows the configuration of a conventional system of this type, in which 1 is a first central processing unit that manages the entire system, for example, a microprocessor with a μCPU mounted on a board; 2 is a subsystem for realizing specific functions, and a second central processing unit 4 (for example, μCPU), a read-only memory unit 5 (for example, ROM), an internal pass line 6, etc. are mounted on the board. It operates under the control of the central processing unit 1 of 1. 3 is the first
An external path line that connects the central processing unit 1 and subsystem 2 of . 7 is a power supply section.

In the above configuration, when power is supplied from the power supply section 7 to the first central processing section 1 and the subsystem 2 through the external path line 3 at the time of system startup, the subsystem 2 supplies power to the first central processing section 1 and the subsystem 2. The unit 4 reads the program from the read-only memory unit 5 and starts executing the program.

(Problem to be Solved by the Invention) However, in the conventional configuration described above, the memory section 5 is read-only and is installed in a state where the program cannot be rewritten. must be removed from the board and a new read-only memory with the required program written must be installed.

For this reason, removing and installing the memory is very time-consuming and requires frequent replacement, leading to the problem of poor contact between the memory and the board.

The present invention solves such conventional problems, and aims to provide an excellent computer system that eliminates the work of removing and installing memory and does not cause poor contact with the board. .

(Means for solving problems) In order to achieve the above purpose, subsystems.

A first switching means for connecting or disconnecting a second central processing unit and an internal signal line, a readable/writable memory means, and a second switching means for switching the connection of this memory means to either an external pass line or an internal pass line. A switching means and a control means for respectively controlling switching of the first and second switching means based on a command signal from the first central processing section are provided.

(Function) According to the above configuration, when changing a program, the first switching means disconnects the second central processing unit from the internal path line, and the second switching means disconnects the memory means from the external path line. line and writes a required program from the first central processing unit to the memory means. Thereafter, the connection of the memory means is switched to the internal pass line, the second central processing unit and the internal pass line are connected, and the written program is executed. In this way, since the program can be changed arbitrarily, there is no need to remove and attach the memory from the board as in the past, and there is no problem of poor contact between the memory and the board.

(Embodiment) FIG. 1 shows an embodiment of the present invention, in which parts having the same functions as those in FIG. 4 and a central processing unit switching unit that switches connection and disconnection with the internal path line 6; 9 a memory unit that can read and write; and 10 a bus switch that switches the connection of the memory unit 9 to the internal path line 6 or the external path line 3. A bus switching control section 11 controls switching of the central processing section switching section 8 and the bus switching section 10 based on a command signal from the first central processing section 1 .

Next, the operation of this embodiment will be explained. First, during normal system startup, power is supplied from the power supply section 7 to the first central processing section 1 and the subsystem 2 via the external path line 3, respectively. At this time, the second central processing unit 4 and the readable/writable memory unit 9 are each connected to the internal path line 6. In the subsystem 2, the second central processing unit 4 reads the program from the memory unit 9 and starts executing the program.

Here, when changing the program, the bus switching control section 11 controls the central processing section switching section 8 based on the command signal from the first central processing section 1 to switch between the second central processing section 4 and the internal Separate from pass line 6.

It also controls the bus switching section 10 to switch the connection of the readable/writable memory section 9 from the internal path line 6 to the external path line 3. In this state, a new execution program is written from the first central processing unit 1 to the readable/writable memory unit 9 via the external path line 3. After the writing is completed, based on the command signal from the first central processing unit 1, the bus switching control unit 11 connects the second central processing unit 4 and the internal path line 6, and also connects the memory unit 9 to the internal path line 6. Switch to pass line 6. The second central processing unit 4 then reads the program written in the memory unit 9 and executes it.

(Effects of the Invention) As described above, according to the present invention, the present invention includes a readable and writable memory section, and controls the switching of the pass line connected to the memory section and temporarily connects the second central processing section and the internal pass line. By disconnecting, the execution program can be easily rewritten as necessary, so every time the program is changed, the read-only memory is removed from the board and the read-only memory for the new program is installed. Therefore, you can eliminate that work.

This also solves the problem of poor electrical contact between the memory and the board caused by replacing the memory.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention;
FIG. 2 is a block diagram showing the configuration of a conventional example. ■...first central processing unit, 2...subsystem,
3 external pass line, 4 second central processing unit, 6 internal pass line, 7 power supply unit,
8...Central processing unit switching unit, 9...Readable memory unit, 10 Bus switching unit, 11...
Bus switching control section. Patent applicant: Matsushita Electric Industrial Co., Ltd. Figure 1 x 2

Claims (1)

[Claims] A first central processing unit that manages the entire system and a plurality of subsystems each having a second central processing unit and each realizing a part of the function are connected by an external signal line,
The subsystem includes a first switching means for connecting or disconnecting the second central processing unit and an internal signal line, a readable/writable memory means, and a connection of the memory means to the external signal line or the internal signal line. and a control means that controls switching of the first and second switching means based on a command signal from the first central processing unit, and when changing the program, The first switching means disconnects the second central processing unit from the internal signal line, the second switching means connects the memory means to the external signal line, and the first central processing unit writes the program to the memory means. After writing the program, the first and second switching means connect the second central processing unit and the internal signal line, and the memory means and the internal signal line, respectively, and execute the written program. Characteristic computer system.