JPS62118446A - Self-diagnosing circuit - Google Patents

Abstract

PURPOSE:To obtain detailed information by small number of hardware by counting and holding number of times of execution of condition judging instruction only during self-diagnosing and reading the counted value by microinstruction. CONSTITUTION:When a microprogram controlling device makes self-diagnosis, a counter 7 counts pulses from a selector 5 only during self-diagnosis. Thereby, the counter 7 counts the number of times of execution of a condition branching instruction during self-diagnosis. A port 8 reads out the value of the counter 7 by microinstruction, selects the counter by a control signal from a decoder 4 and outputs to an ALU 10. In this way, the extent of progress of self-diagnosis can be known even when loop and subroutine are included in a micro program.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Minute Hand) The present invention relates to a self-diagnosis circuit for a microprogram control device.

(Prior Art) Conventionally, various methods have been adopted for displaying the results of self-diagnosis in microprograms for this type of self-diagnosis.

One of the above display methods is the first one that only displays whether or not the diagnosis is possible.
There is a second method in which an error number is set by a microprogram for each unit of diagnosis, and another method is until the self-diagnosis program passes. There is an @80 method for obtaining sheller information about the value of the program counter for a microprogram.

(Problems to be Solved by the Invention) In the self-diagnosis circuit described above, in the first method of displaying only the acceptability of the diagnosis result, the location of the failure becomes unclear. on the other hand,
In the second method of setting error numbers, it is possible to obtain more detailed information by making the unit of diagnosis smaller and specifying more detailed error numbers. It is not realistic to give very detailed error numbers because this will lead to an increase in errors and a decrease in execution speed. Furthermore, in the eighth method of obtaining error information from the value of a program counter, if a subroutine or loop is provided in the diagnostic program, the exact location of the error may become unclear.

As mentioned above, various methods for displaying diagnostic results are known, but
Both methods have the disadvantage of not being able to obtain detailed information with a small amount of hardware.

An object of the present invention is to detect that a conditional judgment instruction included in a microinstruction has been executed, and also to display that the microprogram control device is undergoing self-diagnosis to indicate that the conditional judgment instruction has been executed. By keeping a count of the number of times a condition judgment instruction is executed only during self-diagnosis using a signal, and reading this count value using a microinstruction, the above drawback can be eliminated and detailed information can be obtained with less hardware. An object of the present invention is to provide a self-diagnosis circuit configured as described above.

(Means for Solving the Problems) A self-diagnosis circuit according to the present invention includes an instruction decoder, a selector, a flip-flop, a counter, and a plurality of ports.

The instruction decoder is for executing condition judgment instructions in the microprogram controller.

The selector is for detecting that a conditional judgment instruction has been executed.

The flip 70 knob is for indicating that the microprogram controller is undergoing self-diagnosis.

The counter is a rounding type that counts the number of times a condition judgment instruction is executed during self-diagnosis based on the output of the flip-flop and the output of the selector.

A plurality of ports are for reading the values set in the counters by microinstructions of the microprogram controller.

(Example) Next, the present invention will be explained in detail with reference to the drawings.

FIG. 1 is a block diagram illustrating one embodiment of a portion of a microprogram controller including a self-diagnostic circuit according to the present invention. In FIG. 1, l is a program counter, 2
is ROM, 3 is an instruction register, 4 is an instruction encoder, 5 is a selector, 6 is a flip-flop, 7 is a counter, 8 is a first port, 9 is a second port, IO is an ALU, 11
is an accumulator.

In Figure 1, the microinstruction is program counter 1.
The command is read out from the ROM 2 addressed by , and temporarily stored in the instruction register 3 . The instruction decoder 4 decodes the microinstructions and generates control signals for executing each microinstruction. The selector 5 selects only the conditional branch instruction based on the decoded control signal, and generates a pulse synchronized with the execution of this instruction. The flip-flop 6 is used to hold the state during self-diagnosis, and is set/reset by a microinstruction. The counter 7 counts pulses from the selector 5 only during self-diagnosis. Thereby, the callan j17 counts how many times the conditional branch instruction has been executed during the self-diagnosis. The first port 8 is a circuit that reads the value of the carantuff by a microinstruction, and selects the value of the carantuff based on the control signal from the instruction decoder 4 and outputs it to the ALUIO. The second port 9 selects the values of other registers within the microprogram controller. The accumulator 11 is an ALU
It operates as temporary storage when an operation is performed by IO.

Next, the operation of the self-diagnosis circuit according to the present invention will be explained.

When the microprogram control device performs self-diagnosis, the determination of whether the self-diagnosis result is good or bad is executed by a condition judgment microinstruction. Therefore, by counting the number of times this condition judgment microinstruction has been executed since the start of the self-diagnosis, it is possible to know how far the self-diagnosis has progressed. This means that even if there are loops and subroutines in the microprogram for self-diagnosis, they are counted sequentially, so it is possible to know exactly how far the self-diagnosis has progressed.

At the beginning of the self-diagnosis program, flip-flop 6 is set. Next, a test is performed according to a predetermined procedure, and whether or not the test result is correct is checked using a conditional branch instruction. By executing the above command, a pulse is generated from the selector 5, and the counter 7 is counted up. If the test is successful, what about the next test? conduct. If unsuccessful, the self-diagnosis ends immediately and the flip-flop 6 is reset. Later, by reading the value of Carantuff on the first port 8, it is possible to know how far the test has progressed. The flip-flop 6 is also reset when all tests are successfully completed. In this case as well, it is possible to know that all tests have been completed by later reading the value of color/ri7 from the first port 8.

(Effects of the Invention) As described above, the present invention detects the execution of a condition judgment instruction included in a microinstruction, displays that the microprogram control device is undergoing self-diagnosis, and detects the execution of a condition judgment instruction included in a microinstruction. By keeping a count of the number of times a condition judgment instruction is executed only during self-diagnosis using a signal indicating that the instruction has been executed, and by reading this count value with a microinstruction, a special routine is added to the self-diagnosis microprogram.
(The effect is that detailed self-diagnosis results can be obtained without adding an i7.Furthermore, the present invention facilitates the self-diagnosis microprogram without increasing the microprogram memory capacity or reducing the execution speed.) Another advantage is that it can be created.

[Brief explanation of drawings]

FIG. 1 is a block diagram illustrating one embodiment of a portion of a microprogram controller including a self-diagnostic circuit according to the present invention. l...Program counter 2##-ROM 3...Instruction register 4/fist/instruction decoder 5...-Selector 6...Flip-flop? - Counter 8.9-Fist Port 10 ALU 11 φ Accumulator

Claims (1)

[Claims] an instruction decoder for executing a condition judgment instruction in a microprogram control device; a selector for detecting that the condition judgment instruction is being executed; and an indication that the microprogram control device is undergoing self-diagnosis. a flip-flop for counting the number of times the condition judgment instruction is executed during the self-diagnosis based on the output of the flip-flop and the output of the selector; A self-diagnosis circuit comprising a plurality of ports for reading by microinstructions of a program control device.