Semiconductor integrated circuit device

Details Semiconductor integrated circuit device Semiconductor integrated circuit device

1999-09-20

2002-04-02

Smith, Matthew (Department: 2825)

Computer-aided design and analysis of circuits and semiconductor

Nanotechnology related integrated circuit design

C365S145000

Reexamination Certificate

active

06367050

ABSTRACT:

BACKGROUND OF THE INVENTION
The present invention relates to a semiconductor integrated circuit device and, more particularly, to techniques that may be applied advantageously to one-chip microcomputers.
Some conventional one-chip microcomputers comprise an EPROM (erasable programmable read only memory) to which data processing and system control programs are written once by general-purpose program writer so as to shorten the development time schedule of each microcomputer. One such one-chip microcomputer is described illustratively in Japanese Patent Laid-open No. Sho 61-51659.
A plurality of kinds of microcomputers are provided with EPROM's of different storage capacities for use in diverse applications. From the assortment of these microcomputers, a user selects an appropriate microcomputer having an EPROM of the suitable storage capacity needed to accommodate processing programs addressing the system in which the microcomputer is to be incorporated.
SUMMARY OF THE INVENTION
One-chip microcomputers are utilized in diverse applications. Thus the programs in the EPROM's of one-chip microcomputers differ significantly in size depending on the system to which each microcomputer is destined. In selecting a one-chip microcomputer, the user must make sure that the storage capacity of the memory is a little larger than the size of the programs to be accommodated. This requirement can promote a recent trend of program-storing EPROM's getting larger in their unused storage areas. Another recent trend is that growing quantities of data to be processed, combined with an increasing number of program steps stemming from more and more control functions required, often exceed the initially contemplated capacity of the incorporated EPROM. The latter case makes it unavoidable to remove some of the functions of low priorities from the microcomputer in question.
With a growing number of applications envisaged for one-chip microcomputers, microcomputer manufacturers are required to produce one-chip microcomputers of increasingly numerous specifications including the EPROM storage capacity. Under such circumstances, the number of units produced per product type is becoming smaller. Hence the problem of the manufacturers failing to enjoy the traditional benefit of cost reductions resulting from mass-producing semiconductor chips of limited kinds, a feature so characteristic of the conventional manufacture of semiconductor integrated circuit devices.
It is therefore an object of the present invention to provide a semiconductor integrated circuit device that is convenient to use and is manufactured with high productivity.
Other objects, features and advantages of the present invention will become apparent in the following specification and accompanying drawings.
The invention is outlined illustratively as follows: it envisages a semiconductor integrated circuit device constituted by a one-chip microcomputer that includes a nonvolatile memory circuit to and from which programs and data are written and read at high speed in keeping with the internal processor operating in real time. In the memory circuit, the area for accommodating data processing programs is used as a read-only area, and the remaining area is used for writing and reading data thereto and therefrom.
Given the above arrangements, the inventive semiconductor integrated circuit device is easy to manufacture with high productivity because it eliminates the need for optimally dividing the ROM and RAM storage capacities during manufacture. Furthermore, the inventive device is more convenient to use than ever because it allows the program storage area to be set as desired by the user.


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Shiozaki, Tadashi, “Applying Ferroelectric Thin Film to Integrated Circuits,” Semiconductor World, Dec., 1991, pp. 122-125. (English translation also provided).

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