JPS6014330A - Microprogram controller - Google Patents

Abstract

PURPOSE:To change a specific field of a microcode which is under execution by latching temporarily the execution result of a microprogram and then selecting a part of the microcode or the latched contents. CONSTITUTION:The microcode is stored in a memory 1 and latched by a latch circuit 2 to be executed by a program executing circuit 3. The field of a bus D of the execution result is latched by a latch circuit 4 via a bus (d) and fed to a selection circuit 5 through a bus (e). Then the circuit 3 produces an indication signal through a line (c) to select the contents of the D bus field of the memory 1 or the contents of the D bus field of the circuit 4. If the indication signal indicates the selection of the output of the circuit 4, the circuit 5 selects the contents of the circuit 4. Therefore the circuit 2 fetches the contents out of the circuit 4.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Application) The present invention relates to an information processing device, and particularly to a microprogram control device therein.

(Prior Art) FIG. 1 shows a block diagram of a conventional microprogram control device. In the figure, 1 is a memory that stores microcodes (or microinstructions), 2 is a latch circuit for latching the microcodes stored in memory 1, and 3 is a latch circuit for latching the microcodes stored in memory 1. It is a microprogram execution circuit that executes code. The address of the execution result of the microprogram executed by the microprogram execution circuit 3 is supplied to the memory 1 again through the bus a. The microprogram control device executes the microprogram in the cycle described above.

FIG. 2 shows a typical example of format 1- of the microcode at this time. As is clear from the figure, the microcode is composed of a type field, an A bus, a B bus, a D bus, and an operand.

Among these configurations, the type indicates the type of microcode. As a result, operation type instructions, branch instructions, etc. are determined. The A bus specifies the register to send information to the △ bus, and the B bus specifies the register that sends information to the △ bus.
This field is used to specify the register in which information is set on the bus. On the other hand, the D bus is a field that specifies a register that stores the operation results of the Δ bus and the B bus.

Further, the operand field is a field that specifies an operation between the A and B buses. This content includes, for example, OR, ADD, AND, etc.

As is clear from the above description, in the conventional microprogram control device, the execution result of the microprogram execution circuit 3 is again supplied to the memory 1 that stores the microphone 11 code. Therefore, the conventional microprogram control device has a drawback in that the microcode itself cannot be changed depending on the result of executing the microcode.

(Objective) The object of the present invention is to eliminate the drawbacks of the prior art as described above, and to provide a microprogram control device that is capable of changing specific fields of the currently executing microcode based on the execution results of the microcode. There is a particular thing.

(Summary) A feature of the present invention is to latch a part of the execution result output from the microprogram execution means, and to latch a part of the execution result output from the microprogram execution means, and to
Either one of the latched contents can be selected by a selection instruction from the microphone program execution means:
It is in the point that I made it.

(Example) The present invention will be explained below using examples. FIG. 3 shows an embodiment of the invention. In the figure, 1°2.3 is the first
Indicates the same item or equivalent as shown in the figure.

Further, 4 is a circuit that latches a specific field of the execution result performed by the microprogram execution circuit 3, and 5 is a circuit that latches either a specific field of the microcode storage memory 1 or a specific field stored in the latch circuit 4. A selection circuit that selects based on a selection instruction signal from the program execution circuit 3 is shown.

Next, the operation of this embodiment will be explained. The microcode stored in the microcode storage memory 1 has formats such as type, A bus, B bus, and operand fields that are latched into the latch circuit 2 via bus b. Further, the field of the D bus is supplied to the selection circuit 5 via the bus b'.

5- The microcode latched by the latch circuit 2 is executed by the microprogram execution circuit 3, and the execution result D
The field of the bus is latched into the latch circuit 4 via the bus d. The output of the latch circuit 4 is supplied to the selection circuit 5 through the bus e.

The microprogram execution circuit 3 then uses a line C to select between the contents of the D bus field in the memory 1 storing the microcode or the contents of the D bus field latched in the latch circuit 4. Generates an instruction signal. When the instruction signal is a signal for selecting the output of the latch circuit 4, the selection circuit 5 selects the output of the latch circuit 4.
Select the content. As a result, the latch circuit 2 takes in the contents from the latch circuit 4 instead of the contents from the memory 1. As a result, the microcode can be changed depending on the execution result of the microcode, making it possible to construct a versatile microprogram control device.

6- (Effects) According to the present invention, a specific field of the microcode currently being executed can be changed according to the execution result of the microcode, and a versatile microprogram control device can be provided.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a conventional microprogram control device, FIG. 2 is a diagram showing an example of a typical format of a microcode, and FIG. 3 is a block diagram of an embodiment of the present invention. 1... Microcode storage memory, 2, 4... Ledge circuit, 3... Microprogram execution circuit, 5...
・Selected circuit agent Patent attorney Michito Hiraki and 1 other person 7- Figure 1 Figure 2, Figure 3 = 163-

Claims (1)

[Claims] (1) In a microprogram control device having a microcode storage means, a latch means for latching contents stored in the means, and a microprogram execution means for executing the latched contents, an output from the microprogram execution means is provided. and a selection circuit that selects between the stored result and a part of the microcode stored in the microcode storage means, according to a selection instruction from the microprogram execution means. . A microprogram control device, wherein the selection circuit selects either the execution result or a part of the microcode in the microcode storage means.