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Apparatus for automatically disabling and isolating a computer's original processor upon installation of a processor upgrade card

  • US 5,297,272 A
  • Filed: 08/02/1989
  • Issued: 03/22/1994
  • Est. Priority Date: 08/02/1989
  • Status: Expired due to Term
First Claim
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1. An upgraded computer system, comprising:

  • 1) a system board including at least a part of a first chip set, the first chip set including;

    a) an 80286 processor chip having a HOLD input, the 80286 processor chip having status and control signals of an 80286 timing and format;

    b) an 82C211 chip; and

    c) a numeric processor interrupt disable circuit, receiving an interrupt signal from the 82C211 chip;

    2) an 80386SX plug-in module including;

    a) an 80386SX processor socket in which is inserted an 80386SX processor chip, the 80386SX processor chip having status and control signals of an 80386SX timing and format;

    b) an 80387SX co-processor socket;

    c) translation circuitry which translates status and control signals from the 80386SX timing and format to the 80286 timing and format, the translation circuitry including programmable arrays of logic elements whose composite function is determined by programming a plurality of equations thereinto;

    d) a numeric processor interrupt circuit which generates a plug-in numeric processor interrupt signal under certain conditions;

    e) a first clock selection circuit which determines the characteristics of clock signal which is used by clock generation circuitry within the 82C211 chip; and

    f) an installation announcement circuit, the installation announcement circuit including a connection from an SXINST# pin on a plug-in connector to ground, the connection from the SXINST# to ground providing an installation announcement signal to which the 80286 processor is responsive whenever the plug-in module is installed, the installation announcement signal causing disablement of the 82086 processor without its physical removal from the system board while allowing the 80386SX processor to assume functions in the computer system otherwise performed by the 80286 processor, the installation announcement signal also causing the numeric processor interrupt disable circuit to prevent the interrupt signal from the 82C211 from reaching any portion of the computer system; and

    3) a connector, in electrical contact with both the system board and the installed plug-in module, for carrying the SXINST# signal from the installation announcement circuit on the 80386SX plug-in module to control the HOLD input of the 80286 processor and the numeric processor interrupt disable circuit on the system board.

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