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US 6,148,362 AGranted
Microcomputer using nonvolatile semiconductor memory to store user code/data
AssigneeNEC Corporation
InventorKatsuichi Sagi
Life of this patent
Estimating the term…
Abstract
The microcomputer according to the present invention is prepared with differing address space for use during normal operations and during rewrite control, whereby, when modifying a rewrite control program, the production of new user code/data can be avoided for cases in which there are actually no modifications of the user code/data. In other words, the microcomputer switches between user ROM during normal operation and rewrite control ROM during rewrite control, and user code/data and rewrite control program are arranged in differing address space.
Claims18
A microcomputer comprising:
- a central processing unit (CPU);
- an electrically erasable and rewritable nonvolatile semiconductor memory that stores rewrite user code/data, which is information within user code/data that may be rewritten;
- and
- a mask read-only memory (ROM) that stores non-rewrite user code/data, which is information that does not require rewriting within said user code/data and a rewrite control program, which comprises a program for controlling the rewriting of content stored in said nonvolatile semiconductor memory,
- wherein said non-rewrite user code/data and said rewrite control program are arranged in different address space as seen from said CPU, and
- wherein said different address space is on a physically separate mask ROM.
3 more elements
A microcomputer comprising:
- a central processing unit (CPU);
- an electrically erasable and rewritable nonvolatile semiconductor memory that stores rewrite user code/data, which is information within user code/data that may be rewritten;
- and
- a mask read-only memory (ROM) that stores non-rewrite user code/data, which is information that does not require rewriting within said user code/data and a rewrite control program, which comprises a program for controlling the rewriting of content stored in said nonvolatile semiconductor memory,
- wherein said non-rewrite user code/data and said rewrite control program are arranged in different address space as seen from said CPU,
- wherein said different address space is on a physically separate mask ROM
- wherein said CPU comprises:
- first mode means that designates addresses for said address space in which said non-rewrite user code/data resides, and executes an operation process according to user code/data;
- and
- second mode means that designates addresses for said address space in which said rewrite control program resides, and rewrites the content of said nonvolatile semiconductor memory.
7 more elements
A microcomputer comprising:
- a central processing unit (CPU);
- an electrically erasable and rewritable nonvolatile semiconductor memory for storing rewritable content;
- and
- a first memory for storing non-rewrite user code/data;
- and
- a second memory for storing a rewrite control program, said rewrite control program controlling the rewriting of content stored in said nonvolatile semiconductor memory;
- wherein said first and second memories are physically separate ROMs.
4 more elements
Dependencies are inferred from the claim text.