JPS59180740A - System for diagnosing rom microprogram controlling device - Google Patents

Abstract

PURPOSE:To supply a desired program address to the access of an ROM to diagnose by installing an address memory, into which the program address for accessing the ROM is stored. CONSTITUTION:Before making a diagnosis, the address of a microprogram which is to be diagnosed is stored in an address memory RAM 4 through an interface 5. When the diagnosis is started, the program address stored in the RAM 4 is read out in accordance with the content of a program counter and supplied to an ROM 3 through a multiplexer 2, and then, repetitionary execution of the program to be diagnosed is made to perform the ROM 3. Therefore, a microprogram in an ROM, of which address is fixed, can be operated under a dynamic address.

Description

DETAILED DESCRIPTION OF THE INVENTION (A) Technical Field of the Invention The present invention relates to a method for performing diagnosis by freely setting program steps at the time of diagnosis, regardless of normal fixed program steps.

(b) Background of the Technology Information processing devices perform required processing by executing each instruction of a program consisting of a plurality of instructions. This relationship also applies to devices that execute each instruction as a microprogram.

In such devices, it is necessary to execute arbitrary program steps and diagnose them during development, fault investigation, and maintenance.

The conventional technique for such diagnostics is read-only memory (R
Since the program stored in the OM (OM), for example, a microprogram, is read out and diagnosed using a fixed address, the current situation is that it has not been possible to overcome the problems associated with program diagnosis.

(c) Conventional technology and problems Conventionally, ROM or RAM is used as the control memory used in microprogram control devices.Usually, in such devices, control memory is used to improve depackability during development. RAM is first used as the memory, and ROM is used to reduce the cost when mass-producing and shipping after development.

In this way, even a ROM-based control memory requires fault investigation and maintenance afterward.

In each of these cases, it becomes necessary to partially or completely execute the microprograms in the control memory to diagnose any of the programs. Examples of the arbitrary program to be executed include repeatedly executing an arbitrary instruction, arbitrarily changing the destination of a microprogram, or repeatedly executing a specific program.

In such a case, if the program needs to be changed, the access address of the control memory is fixed, so even if the change is small, the contents of the ROM must be rewritten and replaced. did not become.

Purpose of the Invention The present invention was devised in view of the drawbacks of the conventional methods as described above, and its purpose is to provide a diagnostic method that can eliminate the disadvantages caused by fixed addresses as described above. There is a particular thing.

g) Structure of the Invention The object of the invention is to provide a system for diagnosing a ROM microprogram control device, by providing an address memory in which a program address for accessing the ROM is stored; This is accomplished by accessing the address memory and providing the required program address therefrom for accessing the ROM for diagnosis.

(F) Embodiments of the Invention The present invention will now be described in detail with reference to the accompanying drawings.

The accompanying drawing shows an embodiment of the present invention, and shows the main structure thereof.

In this figure, ] is a program counter whose contents, that is, its address, is supplied to ROM 3 via multiplexer 2, and also to RAM (random access memory).
4 is also supplied. The RAM 4 is configured to receive and store a program address used for accessing the ROM 3 via an interface 5.

Also, the output of RAM4 is sent to ROM3 via multiplexer 2.
connected to. The ROM 3 is a control memory and stores microprograms. 6 is a control circuit connected to the output of ROM3.

Next, the operation of the above-mentioned component device will be explained.

In normal operation, the address output from the program counter 1 is supplied to the ROM 3 via the multiplexer 2, and the microprogram is read from the ROM 3.
It is applied to the control circuit 6 and executed there.

When switching to the diagnosis mode for diagnosing such a normal operating mode, the address of the microprogram to be diagnosed is stored in the RAM 4, which is an address memory, via the interface 5 before starting the diagnosis.

When the diagnosis is started, the microprogram address stored in the RAM 4 is read out according to the contents of the program counter 1, and is supplied to the ROM 3 via the multiplexer 2. Repeatedly execute microinstructions and change destination.

Causes repeated execution of a specific microprogram.

In such a diagnosis, the program configuration can be freely set by appropriately changing the program address written in the RAM 4. Therefore, RO with fixed address
Microprograms in M can be operated under dynamic addressing.

In other words, the conventional technique eliminates the need for a diagnosis that would require rewriting or replacing the ROM.

In the above embodiment, a case has been described in which the microprogram address is stored in the RAM 4 prior to diagnosis, but the RAM 4 may be used as an address memory and the program address may be stored therein in advance.

(G) Effects of the Invention As described above, according to the present invention, the program address to be diagnosed is stored in the address memory, and this is read out and used for diagnosis, even if the address is fixed. Even if the program is a program with a dynamic address, it will be possible to run it with a dynamic address.
Therefore, it will be possible to eliminate the problems that occur with conventional techniques.

[Brief explanation of the drawing]

The accompanying drawings illustrate one embodiment of the invention. In the figure, 1 is a program counter, 2 is a multiplexer,
3 is a ROM, 4 is a RAM, and 5 is an interface. 227-

Claims (1)

[Claims] In a method for diagnosing a ROM microprogram control device, an address memory is provided in which a program address for accessing the ROM is stored, and the RO is used during diagnosis.
A diagnostic method for a ROM microprogram control device, characterized in that the address memory is accessed by a program counter of M, and a required program address from there is used to access the ROM for diagnosis.