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MICROCOMPUTER

  • US 20130290587A1
  • Filed: 04/11/2013
  • Published: 10/31/2013
  • Est. Priority Date: 04/27/2012
  • Status: Active Grant
First Claim
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1. A microcomputer comprising:

  • a CPU that executes selectively (i) a main program and (ii) an onboard rewriting program that executes an onboard rewriting of the main program; and

    a nonvolatile memory that includes (i) a rewriting permitted area where data are enabled to be rewritten and (ii) a rewriting forbidden area where data are forbidden from being rewritten,the rewriting permitted area storing the main program,the rewriting forbidden area storing the onboard rewriting program,the rewriting forbidden area further storing an interrupt vector with respect to each of a plurality of interrupt factors, the interrupt factors being different from each other,the interrupt vector indicating an address of a branch destination when each of the plurality of interrupt factors arises,the microcomputer further comprising;

    a change section that uses the address indicated by the interrupt vector and changes a CPU-accessed address, which is an address accessed by the CPU, into either an address within the main program or an address within the onboard rewriting program according to the main program or the onboard rewriting program, whichever is executed,wherein;

    the main program includes a user vector stored in a predetermined address that is predetermined with respect to each of the plurality of interrupt factors, the user vector indicating an address which stores an interrupt processing program that is executed when each of the plurality of interrupt factors arises; and

    the change section specifies the predetermined address storing the user vector when changing the CPU-accessed address into the address within the main program.

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