JPH04277839A - Semiconductor integrated circuit device - Google Patents

Abstract

PURPOSE:To shorten time required for executing simulation, to shorten time for developing a function module, to load the function module having the large number of gates and to develop the function module having the large number of gates as well. CONSTITUTION:This device is constituted with a built-in CPU module 12 to enable only a mode for directly performing access from an external terminal 2 to an internal bus 4. Namely, the CPU module 12 is constituted by providing only a mode select circuit 6, an ALU or a PLA is not provided, and a ROM or a RAM is not provided, either.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor integrated circuit device (hereinafter referred to as LSI) suitable for use in developing functional modules.

0002

2. Description of the Related Art Conventionally, an LSI of this type, the main part of which is shown in FIG. 2, has been proposed. In the figure, 1 is the LSI main body, 2 is an external terminal, 3 is an input/output port, 4 is an internal bus, 5 is a CPU module, 6 is a mode selection circuit,
7 is ALU (arithmetic and logi
-cal unit), 8 is PLA (program
available logic array), 9 is ROM, 1
0 is a RAM, and 11 is a functional module under development. In such an LSI, when testing the functional module 11, the CPU module 5 sets the mode in which the internal bus 4 can be accessed directly from the external terminal 2. Output port 3 and functional module 11 are connected via internal bus 4 .

0003

As described above, when testing the functional module 11, it is sufficient to have only the mode in which the internal bus 4 can be directly accessed from the external terminal 2, and no other modes are required. Nevertheless, in the conventional LSI shown in FIG.
In addition to providing ALU 7 and P in the CPU module 5,
LA8 is provided for the normal mode required for general products,
That is, it is configured to be able to execute instructions stored in the ROM 9. In other words, circuits that are not originally necessary are provided as an LSI for functional module development. As a result, the number of gates in the entire LSI increases,
There is a problem in that the time required to execute the simulation increases. There is also the problem that the number of gates of a functional module that can be developed is limited, making it impossible to develop a functional module with a large number of gates.

[0004] In view of these points, the present invention makes it possible to shorten the time required to execute a simulation and shorten the development time of a functional module, and also to make it possible to reduce the time required to execute a simulation, and also to reduce the time required to develop a functional module. It is an object of the present invention to provide an LSI that enables the development of functional modules with a large number of gates.

[0005]

[Means for Solving the Problems] The LSI according to the present invention has the following features:
It is configured with a built-in CPU module that enables only a mode in which the internal bus can be accessed directly from external terminals.

[0006]

[Operation] The present invention has a built-in CPU module that enables only a mode in which the internal bus can be accessed directly from external terminals, which simplifies the circuit and reduces the number of gates in parts other than functional modules. be able to.

[0007]

[Embodiment] An embodiment of the present invention will be described below with reference to FIG. Note that in FIG. 1, parts corresponding to those in FIG. 2 are designated by the same reference numerals, and redundant explanation thereof will be omitted. FIG. 1 is a block diagram showing the main parts of an embodiment of the present invention,
In this embodiment, the CPU module 12 is configured with only a mode selection circuit 6, and includes an ALU 7 and a PLA 8.
has not been established. Further, ROM 9 and RAM 10 are not provided. The rest of the structure is similar to the LSI shown in FIG. 2.

According to this embodiment, the functional module 11 can be tested by executing only the mode in which the internal bus 4 can be accessed directly from the external terminal 2.

[0009]

[Effects of the Invention] As described above, according to the present invention, the circuit is simplified by incorporating a CPU module that enables only the mode in which the internal bus can be directly accessed from external terminals. Since it is possible to reduce the number of gates in parts other than functional modules, it is possible to shorten the time required to run simulations and shorten the development time of functional modules. Since modules can be installed, it is also possible to develop functional modules with a large number of gates.

[Brief explanation of the drawing]

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

FIG. 2 is a block diagram showing main parts of an example of a conventional LSI.

[Explanation of symbols]

1 LSI main body 2 External terminal 3 Input/output port 4 Internal bus 6 Mode selection circuit 11 Functional module 12 CPU module

Claims (1)

[Claims] 1. A semiconductor integrated circuit device comprising a built-in CPU module that enables only a mode in which an internal bus can be accessed directly from an external terminal.