JPS5935250A - Program controller - Google Patents

Abstract

PURPOSE:To facilitate the stall state detection of a control program, by detecting that the control does not return from each routine constituting the control program for a specific time or longer. CONSTITUTION:If a stall state caused by a hardware fault, error of a control microprogram, etc., occurs in some routine among an instruction execution part 11, input/output processing part 12, and input/output interruption processing part 13; a flip-flop 2 is set by the output of a timer 1. Then, while the flip-flop is not reset in a program step 9, it is set again by the output of the timer 1 and a counter 4 counts up. When its counted value attains to a specific value, an interruption signal is sent to a mic roprogram control part 8.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical field to which the invention pertains] The present invention relates to a program control device, and particularly to a program control device equipped with means for detecting a program stall state.

[Prior art]

Conventionally, in a program control device, although the control program is often in a stalled state due to a hardware failure or a program error in the control program, there is a means for easily detecting this stalled state. 0 [Object of the Invention] The object of the present invention is to detect whether control is not returned from each routine constituting the control program for a certain period of time or more, so that the program of the control program can avoid software failures. - It is an object of the present invention to provide a program control device having means for detecting a stall state of a control program due to a cause such as a mistake.

[Structure of the invention]

According to the present invention, a flip-flop which is set and reset every time a certain period of time has passed and which can be programmed;
a counter that counts when the flip-flop is already set every time the predetermined time elapses;
There is obtained a program control device characterized in that it includes means for generating an interrupt when the counter counts a certain number.

[Explanation of Examples]

Next, an embodiment of the present invention will be explained by taking as an example a micro-program controlled computer having a configuration as shown in FIG.

In FIG. 1, a microprogram control device 8 controls the entire microprogram-controlled computer by executing a control microprogram stored in the main storage device 6. As shown in FIG.

The output of the hardware timer 1 is fed to the flip-flop 2 by the output of the flip-flop 2, while the output of the AND circuit 3 is fed to the clock terminal of the counter 4. The output of the counter 4 indicating the end of counting is supplied to the interrupt control section 7 as a single input, and the output of the interrupt control section 7 is supplied to the microprogram control device 8 as a generated interrupt signal. There is.

Furthermore, the reset terminal of the clip-flop 2 has a
One decode output signal of the input/output instruction decode section 5 is supplied.

FIG. 2 shows the configuration of the control microprogram. In FIG. 2, the instruction execution unit 11 that controls the execution of software instructions existing in the main memory 6 and the input/output processing unit 12 are in normal mode. Further, the input/output interrupt processing section 13 is a processing routine that operates respectively in the interrupt mode, and is a basic routine that is a component of the control microprogram. Note that the judgment step 10 is for determining whether or not it is necessary to perform input/output processing, and normally control is passed to the instruction execution unit 11, but when the data transfer related to input/output is completed and the Control is passed to the input/output processing section 12 when it is necessary to perform termination processing or when executing input/output activation processing for executing an input/output instruction detected by the instruction execution section. The input/output interrupt processing section 13 is a section that controls data transfer related to input/output operations in the interrupt mode.

The instruction execution unit 11 described above. Input/output processing unit 12.
Each routine of the input/output interrupt processing section 13 must be designed to complete its processing within a certain period of time under normal conditions. Further, the output instruction 9 is a microprogram step that is always executed in the direct curve of the judgment step 1O.
By executing this output command, the flip/
Flop 2 is reset.

In the above microprogram controlled calculator,
Hardware timer 1 sets 7 trips 70 trips 2 at fixed time intervals, but if microprogram control is being performed normally as described above, microprogram step 9 will be executed within a fixed time. Therefore, the flip-flop 2 must be reset within a certain period of time after being set. Here, it is assumed that the output signal generation interval of hardware timer 1 is sufficiently wider than the maximum time interval at which microprogram step 9 is executed.

However, the instruction execution unit 11. I/O termination processing unit 1
2. In any routine of the input/output interrupt processing unit 13,
If a stall condition occurs due to a hardware failure or a program Φ error in the control microprogram, the microprogram step 9 will not be executed for a long time, so the clip 70 tube 2 will not be output from the hardware own timer 1. After being reset, the value at any point in time when it is not reset by program step 9 becomes 1, which results in the counting of counter 4.

When the above process is repeated a certain number of times, the count value of the counter 4 reaches a certain value, and at this time, the output of the counter 4 is passed through the interrupt control section 7 to the microprogram control device 8. , as an interrupt signal. In this case, the interrupt level of the interrupt signal needs to be higher than the interrupt level of the input/output interrupt, taking into consideration the case where a stall occurs in the input/output interrupt processing section 6-13. .

The interrupt processing routine started as described above saves necessary information such as register information, and then performs appropriate processing such as starting a self-diagnosis microprogram.

[Kishi Zuoiip] As explained above, the present invention includes hardware timers, counters, flip-flops, etc. in a program control device.
By having a small amount of hardware such as a flop,
This has the effect that it becomes possible to easily detect a stalled state of a control program.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an example of a microprogram-controlled computer to which the invention is applied, and FIG. 2 is a block diagram of a control microprogram in the microprogram-controlled computer. 1... Hardware timer, 2...
Flip-flop, 3...AND circuit, 4.
... Counter, 5 ... Input/output instruction decoding section, 6 ... Main storage device, 7 ... Interrupt control section, 8 ......・Microprogram control device, 9...Output command for flip-flop reset, 10...Required for input/output completion processing・
Step for determining unnecessaryness, 11... Instruction execution unit, 12,... Input/output termination processing unit, 13...
...I/O interrupt processing section. 1 @ Diagram Z

Claims (1)

[Claims] It is set and reset every time a certain period of time passes by program 2.
a 7-bit clock that can be programmed by the program; a counter that counts when the flip-flop is already set every time the predetermined time period elapses; and an interrupt that generates an interrupt when the counter counts a predetermined number. A program control device comprising means for.