JPH04205529A - Microprocessor - Google Patents

Abstract

PURPOSE:To reform a desired microprocessor in a short manufacturing period by replacing the microprogram of a storage circuit with the output of a microprogram generating circuit that is designated by an aluminum master slice. CONSTITUTION:A storage circuit 1 is provided to store a microprogram together with a program counter 2 which shows the address of the circuit 1, an address detecting circuit 3 which inputs the output of the counter 2, and a microprogram generating circuit 4 which generates an optional microprogram through a switch circuit. Furthermore a selection circuit 5 contains the output of the circuit 1 connected to one of both inputs, the output of the circuit 4 connected to the other input, and the output of the circuit 3 connected to the selection input respectively. An instruction decoder 6 is added to decodes the output of the circuit 5 into an instruction together with a controlled circuit 7. In such a constitution, an optional program can be carried out just with change of an aluminum master slice of the circuit 4 contained in an upper layer of an LSI.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a microprocessor, and particularly to a microprocessor in which a microprogram is built into an LSI.

[Conventional technology]

As shown in FIG. 3, a conventional microprocessor has a memory circuit 8 containing a microprogram, a program counter 9 that controls the memory circuit, and an instruction decoder 10 that converts the microprogram read from the memory circuit into instructions. It has a controlled circuit 11 that is controlled by the converted instructions.

The memory circuit is constituted by a mask ROM, and in order to reduce the area occupied by the chip, data is switched by switching the diffusion layer under the gate of the transistor.

[Problem to be solved by the invention]

In conventional microprocessors, the switching is done from the diffusion layer under the gate of the transistor whose microprogram is to be changed, and this diffusion process is difficult for LSI
Since it is at the beginning of the manufacturing process, it has the disadvantage that it takes a long time to manufacture.

[Means to solve the problem]

The microprocessor of the present invention generates an arbitrary microprogram using a memory circuit that stores a microprogram, a program counter that indicates the address of the memory circuit, an address detection circuit that receives the output of the program counter, and a switching circuit. A microprogram generation circuit, a selection circuit in which the output of the storage circuit is connected to one input, the output of the microprogram generation circuit is connected to the other input, and the output of the address detection circuit is connected to the selection input; It has an instruction decoder that decodes six words into instructions, and a controlled circuit.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a block diagram of one embodiment of the present invention.

A memory circuit 1 that stores a microprogram, a program counter 2 that indicates the address of the memory circuit 1, an address pressure detection circuit 3 that receives the output of the program counter 2, and a microprogram that generates an arbitrary microprogram using a switching circuit. A generation circuit 4, a selection circuit 5 in which the output of the memory circuit 1 is connected to one input, the output of the microprogram generation circuit 4 is connected to the other input, and the output of the address detection circuit 3 is connected to the selection input; It is composed of an instruction decoder 6 that decodes the 8 outputs of the circuit 5 into instructions, and a controlled circuit 7.

Next, the operation will be explained. Normally, the microprocessor inputs the microprogram at the address of the storage circuit l indicated by the program counter 2 to the instruction decoder 6 via the selection circuit 5. The microprogram input to the instruction decoder 6 is decoded into instructions, and the controlled circuit 7 is operated in accordance with the instructions. Repeat this series of actions to obtain the desired action.

Next, if the address detection circuit 3 detects address n (n is an integer greater than or equal to 0), when the value of the program counter 2 reaches address n, the address detection circuit 3 inputs a switching signal to the selection circuit 5. do. In response to its input, the selection circuit 5 switches the signal input to the instruction decoder 6 from the output of the storage circuit 1 to the output of the microprogram generation circuit 4. The instruction decoder 6 decodes the output of the microprogram generation circuit 4 into instructions, and operates the controlled circuit 7. Here, the microprogram generation circuit 4 is
As shown in Figure 2, “H” level 401 or L’
Aluminum master slice 5W403,40 corresponding to each bit of the microprogram connected to level 402
4,405. ..., 406 to output any microprogram 407, 408, 409 .
..., 410 can be obtained. When using this circuit, for example, by setting address 0 as n and inserting a jump instruction into the microprogram generation circuit 4, the 5W of aluminum master slice 403, 404, 405°.
..., it becomes possible to execute the program from the address specified by 406, and if several different programs are stored in the memory circuit 1 in advance, the 5W403 of the aluminum master slice of the microprogram generation circuit 4
, 404, 405. ....

Any program can be executed by simply changing 406.

〔Effect of the invention〕

As explained above, the microprocessor of the present invention has
The microprogram at address n of the memory circuit 1 is transferred to an aluminum master slice of 5W403°404.405. ...,
By replacing the output of the microprogram generation circuit 4 specified by 406, the original program flow can be changed.
Part of the data can be changed. Here, since the aluminum manufacturing process is close to the final stage of the LSI manufacturing process, it has the advantage that desired improvements in the microprocessor can be made in a short manufacturing period.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram of the present invention, FIG. 2 is a configuration example of a microprogram generation circuit, and FIG. 3 is a block diagram of a conventional example. 1... Memory circuit, 2... Program counter, 3
... Address detection circuit, 4 ... Micro program generation circuit, 5 ... Selection circuit, 6 ... Instruction coder, 7 ... Controlled circuit, 40
1..."H' level, 402... L° level, 403°404.405..., 406...
・Aluminum master slice SW, 407, 408, 40
9. .... 410...Microblock output, 8...
・Memory circuit, 9...Program counter, 10
...Instruction Tekota, 11...
...Controlled circuit. Agent Patent Attorney Oto Uchihara Figure 2

Claims (1)

[Claims] In a microprocessor that controls a controlled circuit using a microprogram, a memory circuit that stores the microprogram, a program counter that indicates an address of the memory circuit, and an address detection circuit that outputs the output of the program counter;
A microprogram generation circuit that generates an arbitrary microprogram using a switching circuit, and the output of a storage circuit are connected to one input, the output of the microprogram generation circuit is connected to the other input, and the output of the address detection circuit is connected to the selection input. A microprocessor consisting of a connected selection circuit and an instruction decoder that decodes the output of the selection circuit into instructions.