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User initiated microcode modification

a micro-computer and instruction technology, applied in the field of micro-computers, can solve problems such as security problems of programs, inability of users to designate desired instruction word sets, and inability to produce application software. the effect of maintaining security

Inactive Publication Date: 2005-05-26
ABOV SEMICON
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0020] An object of the present invention is to provide an instruction decoding unit in a microcomputer having an instruction word capable of being selected by a user to conveniently produce application software and maintain security.

Problems solved by technology

However, the instruction decoding unit in the conventional microcomputer has several problems.
First, since the conventional microcomputer has fixed instruction sets, it may be impossible for the user to designate a desired instruction word set.
Second, when a program code of the user is open, it is easy to decode the program code using a fixed instruction map, thereby likely causing security problems for the program.

Method used

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  • User initiated microcode modification
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Examples

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first embodiment

[0033]FIG. 2 is a block diagram illustrating an instruction decoding unit in a microcomputer according to the present invention.

[0034] As shown in FIG. 2, an instruction decoding unit in a microcomputer according to the first embodiment of the present invention includes an instruction register 21 for storing instructions fetched through a data bus from a memory in which application software selected by a user, an instruction decoder 22 for decoding instruction codes corresponding to the instructions stored in the instruction register 21 and for designating micro-instructions to be executed, a micro-ROM 23 for outputting a series of the micro-instructions (combination of control signals) from micro-instruction signals designated by the instruction decoder 22, and a user instruction selector 24 for selecting or changing the micro-instructions from the micro-ROM 23 in response to a user selection so as to change the operation of an instruction word.

second embodiment

[0035]FIG. 3 is a block diagram illustrating an instruction decoding unit in a microcomputer according to the present invention.

[0036] As shown in FIG. 3, an instruction decoding unit in a microcomputer includes an instruction register 31 for storing instructions fetched through a data bus from a memory in which application software selected by a user is stored, an instruction decoder 32 for decoding instruction codes corresponding to the instructions stored in the instruction register 31 and for designating micro-instructions to be executed, an instruction code selector 35 connected between the instruction register 31 and the instruction decoder 32 for allowing a user to select a signal corresponding to at least one of a plurality of instruction maps, a micro-ROM 33 for outputting a series of the micro-instructions (combination of control signals) designated by the instruction decoder 32, and a user instruction selector 34 for selecting or changing the micro-instructions of the mic...

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PUM

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Abstract

An instruction decoding unit in a microcomputer is disclosed having an instruction word capable of being selected by a user to conveniently produce application software while maintaining security. The decoding unit in a microcomputer includes an instruction register for storing instructions fetched from a memory, an instruction decoder for decoding instruction codes of the instructions stored in the instruction register and for designating micro-instructions to be executed, a micro-ROM for outputting a series of the micro-instructions designated by the instruction decoder, and a user instruction selector for selecting or changing the micro-instructions of the micro-ROM in response to user's selection so as to change the operation of an instruction word.

Description

CROSS REFERENCE TO RELATED APPLICATION [0001] This application is a Divisional of co-pending application Ser. No. 09 / 927,398, filed on Aug. 13, 2001, which is a continuation of 09 / 228,550, filed Jan. 12, 1999 and for which priority is claimed under 35 U.S.C. § 120; and this application claims priority of Application No. 98-00735 filed in Korea on Jan. 13, 1998 under 35 U.S.C. § 119; the entire contents of all are hereby incorporated by reference.BACKGROUND OF THE INVENTION [0002] 1. Field of the Invention [0003] The present invention relates to a microcomputer and its use, and more particularly, to an instruction decoding unit in a microcomputer having an instruction word capable of being selected by a user and a method of encoding / decoding the instruction word. [0004] 2. Discussion of the Related Art [0005] Generally, a microcomputer includes a central processing unit (CPU), a memory, peripheral units, and an input / output unit on a chip. Recently, microcomputers have been widely us...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): G06F9/30G06F9/22G06F9/318
CPCG06F9/30181G06F9/30145G06F9/30
Inventor CHO, DONG SOO
Owner ABOV SEMICON