JPH04241645A - Execution history storing system - Google Patents

Abstract

PURPOSE:To obtain important information required for clearing up the cause of a problem when the problem occurs even when the execution of a microinstruction is suppressed for a long time. CONSTITUTION:A control storage 1 for storing microprograms, microinstruction register 2 for storing a microinstruction read out from the storage 1, tracer memory 4 for storing a specific logical signal, and a means which inhibits the writing to the memory 4 when the, execution of the microinstruction is inhibited are provided.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an execution history system for a data processing apparatus using microprograms.

0002

2. Description of the Related Art In a data processing device using a microprogram, an execution history storage device is provided to record a history of the execution addresses and specific logic signals of the microprogram as a clue to clarify the cause of abnormalities or exceptions in the device. Sometimes.

In such a data processing device, a microinstruction read from a control memory is stored in a microinstruction register, and a portion of the microinstruction is decoded by a decoder to become a control signal for executing the microinstruction. At the same time, specific logic signals are stored in the tracer memory.

These operations are sequentially repeated to form a microprogram sequence, but if an abnormality or exception is detected, updating of the tracer memory is also stopped, and the microprogram stored in this tracer memory is By analyzing the execution history of , it becomes easy to find the cause of device abnormalities and exceptions.

However, since the tracer memory has a limited capacity, it cannot store all the data necessary for investigating the cause of an abnormality or exception. Therefore, conventionally, when data is stored in the entire storage area of the tracer memory, a method has been adopted in which older data is sequentially overwritten only at the beginning.

[0006]

[Problems to be Solved by the Invention] In the conventional execution history storage method described above, even if the execution of a microinstruction is inhibited due to various factors during the execution of a microprogram, the execution address of the microprogram or a specific logic signal cannot be stored. is recorded in the tracer memory every clock, so if microinstruction execution is inhibited for a long time, it becomes difficult to find the cause of device abnormalities or exceptions.

[0007]

[Means for Solving the Problems] The execution history storage system of the present invention includes a control memory for storing microprograms, a microinstruction register for storing microinstructions read from the control memory, and a tracer for storing specific logic signals. The tracer memory includes a memory and means for inhibiting writing to the tracer memory when execution of a microinstruction is inhibited.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a block diagram of an embodiment of the present invention.

Referring to FIG. 1, this embodiment includes a control memory 1, a microinstruction register 2, a decoder 3, a tracer memory 4, a pointer 5, and a microinstruction execution inhibit signal 500.
Consisting of

The instructions constituting the microprogram stored in the control memory 1 are stored in the microinstruction register 2 when read out. A part of the microinstruction stored in the microinstruction register 2 is decoded by the decoder 3 and becomes a control signal 100 for executing the microinstruction. On the other hand, part of the microinstructions stored in the microinstruction register 2 becomes the next execution address signal 200, which specifies the address on the control memory 1, and stores the next address instruction in the microinstruction register 2.

[0011] This series of operations forms a microinstruction execution sequence. The next execution address signal 200 and the specific logic signal 400 are stored in the tracer memory 4 at the address indicated by the pointer 5, and the value of the pointer 5 is increased by 1 at the same time as the storage. In particular, when the pointer 5 points to the last address of the tracer memory 4, the first address of the tracer memory 4 is set to the pointer 5 at the same time as storage, thereby realizing circular use of the memory.

[0012] When the execution of a microinstruction is inhibited due to various factors during the execution of the microprogram program, the microinstruction execution inhibition signal 500 becomes "ON". When the signal 500 becomes “ON”, the microinstruction execution inhibit signal 50 is turned on again.
Until 0 becomes "OFF", the microinstruction register 2 and other microinstructions and information necessary for execution are all in the HOLD state. At this time, pointer 5 is also in the HOLD state. Therefore, the next execution address signal 200 and the specific logic signal 400 are stored in the tracer memory 4 at the same location.

By reading out the history of a series of next execution address signals 200 and specific logic signals 400 stored in the tracer memory 4, it is possible to know the execution history of the microprogram up to its stop. HOL pointer 5 while microinstruction inhibit signal 500 is “ON”
By setting it in the D state, writing to the tracer memory 4 can be inhibited when execution of a micro instruction is inhibited.

[0014]

[Effects of the Invention] According to the present invention, when microinstruction execution is inhibited due to various factors during microprogram execution, microinstruction execution can be inhibited for a long time by inhibiting writing to the tracer memory. Even when a problem occurs, important information can be obtained for investigating the cause of the problem.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an embodiment of the present invention.

[Explanation of symbols]

1 Control memory 2 Microinstruction register 3 Decoder 4 Tracer memory

Claims (1)

[Claims] 1. A control memory that stores a microprogram, a microinstruction register that stores microinstructions read from the control memory, a tracer memory that stores specific logic symbols, and a control memory that stores microinstructions when execution of the microinstructions is suppressed. An execution history recording method comprising: means for inhibiting writing to the tracer memory.