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EP0239283A2 Expired / Lapsed EP ⏱️ 0.0 years remaining

Microcomputer

Assignee: Hitachi Ltd
•
Filing: 1987-03-11
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Granted: —
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Expires: 2007-03-11
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Abstract

Abstract A single chip type microcomputer includes a central processing unit (CPU) (l), a random-access memory (RAM) (2), a mask read-only memory (mask ROM) (3) and a writable ROM such as an electrically erasable and programmable read-­only memory (EEP-ROM) (4). The writable ROM (4) stores both the user program and data to be preserved. The mask ROM (3) stores a write control program for controlling the write operation to the writable ROM, and the address positions of the writable ROM and the mask ROM (3) in the address space of the CPU are mutually different. The pro­portion of size of the user program region and the data region in the writable ROM can be selected in arbitrary proportions. In this way, only a single writable ROM (4) is needed, but data may be preserved semi-permanently in the writable ROM (4) whenever necessary.

Inventors

  • 👤 Naoki Mitsuishi

Bibliographic Details

Application Number —
Jurisdiction EP
Data Source google_patents
Last Synchronized 2026-10-27 23:40
CPC Classifications
G; G06; G06F; G06F15/00; G06F12/00; G06F12/02; G06F12/0223; G06F15/76; G06F15/78; G06F15/7807; G06F15/7814; G06F21/00; G06F21/70; G06F21/78; G06F21/79

Claims Analysis

Total Claims: 4
Claim 1
Independent Claim 76 words
A microcomputer having a central processing unit (l) and a writable ROM (4), characterized in that both a program and data may be written into the writable ROM (4), the microcomputer includes a further memory (3) for storing a write control program for controlling the write operation to the ROM (4), and the address positions of the ROM (4) and the memory (3) in the address space of the central processing unit (l) are mutually different.
Claim 2
Dependent Claim 76 words
A microcomputer having a central processing unit (l) and a writable ROM (4), characterized in that both a program and data may be written into the writable ROM (4), the microcomputer includes a further memory (3) for storing a write control program for controlling the write operation to the ROM (4), and the address positions of the ROM (4) and the memory (3) in the address space of the central processing unit (l) are mutually different.
Claim 3
Dependent Claim 21 words
A microcomputer according to claim l, wherein the further memory (3) for storing the write control program is a mask ROM.
Claim 4
Dependent Claim 21 words
A microcomputer according to claim l or 2, wherein the further memory for storing the write control program is a RAM.

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