Detection of uncorrectable re-grown fuses in a microprocessor

A method for operating a microprocessor, the method comprising:

• reading a first plurality of fuses, wherein a predetermined number of the first plurality of fuses are selectively blown, wherein control values are provided from the first plurality of fuses to circuits of the microprocessor to control operation of the microprocessor;
• counting a number of the first plurality of fuses that are blown;
• reading a predetermined number from a second plurality of fuses, wherein the second plurality of fuses are blown with the predetermined number of the first plurality of fuses that are blown;
• comparing the counted number with the predetermined number read from the second plurality of fuses;
• and
• preventing the microprocessor from fetching and executing user program instructions if the number counted from reading the first plurality of fuses does not equal the predetermined number read from the second plurality of fuses.

A method for manufacturing a microprocessor having a capability to detect an incorrect control value provided by a first plurality of fuses of the microprocessor to circuits of the microprocessor during operation of the microprocessor to control operation thereof, the control value being incorrect because a blown one or more of the first plurality of fuses is providing its non-blown value rather than its blown value, the method comprising:

• determining the control value;
• counting a number of the first plurality of fuses to be blown to create the control value in the first plurality of fuses;
• blowing the control value into the first plurality of fuses;
• and
• blowing into a second plurality of fuses of the microprocessor the number of the first plurality of fuses blown to create the control value.

A computer program product encoded in at least one computer readable medium for use with a computing device, the computer program product comprising:

• computer readable program code embodied in said medium, for specifying a microprocessor, the computer readable program code comprising:
• first program code for specifying a first plurality of fuses, a predetermined number of which are selectively blown, wherein control values are provided from the first plurality of fuses to circuits of the microprocessor to control operation of the microprocessor;
• and
• second program code for specifying a second plurality of fuses, blown with the predetermined number of the first plurality of fuses that are blown;
• wherein, in response to being reset, the microprocessor is configured to:
• read the first plurality of fuses and count a number of them that are blown;
• read the predetermined number from the second plurality of fuses;
• compare the counted number with the predetermined number read from the second plurality of fuses;
• and
• prevent itself from fetching and executing user program instructions if the number counted from reading the first plurality of fuses does not equal the predetermined number read from the second plurality of fuses.