JPS59170948A - Address control system of microprogram - Google Patents

Abstract

PURPOSE:To execute easily the change or correction of a microprogram by writing the existence of the change of each microinstruction, substitute address information and a substitute microinstruction word in an unused area in a microprogram memory. CONSTITUTION:If it is supposed that an error is detected in a microinstruction word stored in address ''N'' of a microprogram memory 1 and address ''Q'' is unused address, change indication information indicating the changes of address part information and instruction part information are additionally written in a change indication part in address ''N''. In addition, ''Q'' is additionally written in a substitute address part as substitute address information and a correct microinstruction word is additionally written in the address ''Q''. An address control circuit 5 can detect the stored address ''Q'' of a microinstruction to be executed successively by said substituted address information.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a microprogram address control system in a microprogramming type arithmetic processing device.

[Prior art]

Conventionally, arithmetic processing is performed based on a microinstruction word, which consists of an instruction part that instructs the content of the new arithmetic processing to be executed, and an address part which instructs the address of the microprogram memory where the microinstruction word to be executed next is stored. A microprogramming type arithmetic processing device that sequentially executes the following is known.

FIG. 1 is a block diagram showing the configuration of a conventional arithmetic processing device of this type. In the figure, (1) is a microprogram memory that stores a plurality of microinstruction words consisting of an instruction part and an address part, and (2) is a microprogram memory that stores a plurality of microinstruction words consisting of an instruction part and an address part. This is a microinstruction register consisting of two register sections (22), and the instruction section information output from the register section (21) is given to the arithmetic control circuit (4) via an information line (31). 1, the address section information output from the second register section (22) is given to the address control circuit (5) via the information line (32). In this case, the arithmetic control circuit (4) generates status information indicating the arithmetic result, and this status information is input to the address control circuit (5) via the information line (41).

On the other hand, address information is given to the microprogram memory (1) from an address control circuit (5) via a microaddress line (51).

In such a configuration, microprogram memory (
The microinstruction word read from 1) is stored in the microinstruction register (2) as a new microinstruction word to be executed after the arithmetic processing based on the microinstruction word currently stored in the microinstruction register (2) is completed. be remembered.

Then, the arithmetic control circuit (4) executes an arithmetic operation based on the instruction part information of the microinstruction word given from this register (2). Further, the address control circuit (5) is connected to the information line (
Based on the address part information of the microinstruction word given from 32) and the status information given from the arithmetic control circuit (4), the microprogram memory (1) in which the microinstruction word to be executed next is stored is The address is determined and applied to the microprogram memory (1) via the microaddress line (51).

By repeating the above operations, it is possible to obtain calculation results corresponding to the microinstruction word group stored in advance in the microprogram memory (1).

By the way, in this type of arithmetic processing device, the microprogram memory (1) is generally configured as a read-only memory, and microinstructions are stored in this read-only memory in order according to their execution order. Common.

However, the combination of microinstructions stored in the microprogram memory (1) is not always perfect, and errors may sometimes be detected. For this reason,
If a mistake is found in the combination of micro-instructions, either replace it with a read-only memory that stores the correct combination of micro-instructions, or delete all the original memory contents and then store the most difficult combination of micro-instructions in order. The disadvantage is that changing the microinstruction word is extremely troublesome.

[Summary of the invention]

The present invention has been made to solve these drawbacks, and its purpose is to provide a microprogram address control system that allows microprograms to be changed and modified extremely easily.

To this end, the present invention has a structure in which each microinstruction word is provided with a change instruction section that indicates whether or not the contents of the address section and instruction section should be changed, and an alternative address section that indicates an alternative address. When a micro-instruction word is discovered, address section information and instruction section information change instruction information and alternative address information are added to this micro-instruction word, and the correct micro-instruction is added to the unused address indicated by the alternative address information. The microinstruction word is newly stored, and the microinstruction word specified by the alternative address information is executed under the condition that the microinstruction word to which change instruction information is added is read.

Embodiment of the invention] FIG. 2 is a pronk diagram showing an embodiment of the invention,
The same parts as in Fig. 1 are indicated by the same symbols 1. In Fig. 2, the difference from Fig. 1 is the microinstruction register (2).
) is added with a third register section (23) that stores change instruction information of address section information and instruction section information and a fourth register section (24) that stores alternative address information, and the change instruction information is sent to the information line (33). ) to the arithmetic control circuit (4) and the address control circuit (5), and alternative address information is supplied to the address control circuit (5) via the information line (34).

In such a configuration, if it turns out that the microinstruction word stored at address N of the microprogram memory (1) is incorrect, and assuming that address Q is an unused address, in such a case, Adds and writes change instruction information indicating that there is a change in address information and instruction section information in the change instruction section at number N, and then adds and writes "Q" as alternative address information in the alternative address section. Add the correct microinstruction word to Q and add 1
: A process of filling is performed.

By doing this, after the microinstruction word at address N is stored in the microinstruction register (2), the change instruction information constituting this microinstruction word is transferred to the arithmetic control circuit (4) and the address control circuit (5). ) K is given. That is,
The fact that the microinstruction word at address N has been changed is transmitted to the arithmetic control circuit (4) and address control circuit (5).

Then, the arithmetic control circuit (4) completely ignores the instruction part information given via the information line (31) and does not execute anything.

On the other hand, the address control circuit (5) determines that the storage address of the next microinstruction word to be executed is "Q" based on the alternative address information.
Knowing this, I put “Q” on the micro address line (51).
”. With such an operation, the arithmetic processing based on the microinstruction word at address N where p and change instruction information are additionally written will not be executed in the same way, and the alternative address information will be output in the next control cycle. Address Q specified by
Arithmetic processing based on the microinstruction word is executed.

Therefore, by simply adding change instruction information, alternative address information, and alternative microinstructions, it is possible to change the combination of microinstructions to the correct one.

Note that the alternative address information may not only directly specify an alternative address, but may also indirectly specify an alternative address.

〔Effect of the invention〕

As described above, according to the present invention, since it is possible to display that each microinstruction word has been changed, as long as there is an unused area in the microprogram memory, change instruction information, alternative address information, and alternative address information can be displayed. The microprogram can be changed or modified extremely easily by simply adding and writing the following microinstruction words.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of a conventional microprogramming type arithmetic processing device, and FIG. 2 is a block diagram showing an embodiment of the present invention. (1)...Micro program memory, (2)...
... Microinstruction register, (4) ... Arithmetic control circuit, (5) Address control circuit. Agent Shin Kuzuno - Figure 1 Figure 2

Claims (1)

[Claims] Arithmetic processing is executed sequentially based on microinstructions, which consists of an instruction part that instructs the content of the new arithmetic processing to be executed, and an address part which instructs the address of the microprogram memory where the microinstruction to be executed next is stored. In an arithmetic processing unit, each microinstruction word has a structure in which a change instruction part that instructs whether or not the contents of the address part and the instruction part are to be changed, and an alternative address part that instructs an alternative address, and the change instruction part Under the condition that the contents of the address field and the instruction field are instructed to be changed by , the address information indicated by the alternative address field is given to the microprogram memory, and the microinstruction word stored at the address is executed. A microprogram address control method featuring: