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Semiconductor integrated circuit with functional blocks capable of being individually tested externally

  • US 5,416,919 A
  • Filed: 12/21/1992
  • Issued: 05/16/1995
  • Est. Priority Date: 07/19/1989
  • Status: Expired due to Term
First Claim
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1. A semiconductor integrated circuit formed on a single semiconductor chip and including an address bus, a data bus and a control bus, said semiconductor integrated circuit comprising:

  • a central processing unit for performing arithmetic processings;

    peripheral circuits associated with said central processing unit;

    external terminals connected to said address bus, said data bus and said control bus communicating with external devices;

    a test mode setting circuit connected to said external terminals for receiving test signals inputted through said external terminals, and generating control signals in response to said inputted test signals; and

    a signal control circuit connected to said address bus, said data bus and said control bus,said signal control circuit having means for connecting one of said central processing unit and said peripheral circuits to said address bus, said data bus and said control bus in response to said control signals received from said test mode setting circuit for selecting said one of said central processing unit and said peripheral circuits to receive digital signals from said address bus, said data bus and said control bus and to output digital signals to said data bus so that said selected one of said central processing unit and said peripheral circuits operates with said buses.

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