Microprocessor Re-writable Non-volatile State via Blowable Fuses
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Solution Overview
Problem
Existing microprocessors lack a cost-effective and secure method for implementing non-volatile, re-writeable memory within the processor itself, as fabricating FLASH memory on the die or using a separate NVRAM die increases costs and is susceptible to security breaches.
Innovation Solution
Incorporating a re-writeable non-volatile state (RNS) embodied as a plurality of fuses within the microprocessor, allowing program-controlled writing and reading, with a Boolean logic unit and fuse blowing device to manage the fuses, providing a secure and cost-effective alternative to external NVRAM.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If FLASH memory is fabricated on the microprocessor die, then non-volatile re-writable storage is achieved, but manufacturing cost increases
Solution Approach 1:
The patent uses inexpensive fuse elements that can be blown and re-blown multiple times as the storage medium. These fuses are much cheaper than FLASH memory cells, achieving non-volatile re-writable storage at a lower manufacturing cost. The fuses are designed to be disposable in the sense that they are simple, low-cost components that provide the required storage function without the high fabrication costs of FLASH memory.
Solution Approach 2:
The patent changes the physical state of the fuse elements between unblown and blown states to represent binary data. By controlling the blowing and re-blowing of fuses through parameter changes in the fuse blowing device, the system achieves re-writable non-volatile storage without requiring complex FLASH memory fabrication processes.
2Reliability
If a separate NVRAM die is added to the microprocessor package, then non-volatile storage is provided, but package cost increases
Solution Approach 1:
The patent merges the non-volatile storage function directly into the microprocessor by integrating fuse elements and a fuse blowing device within the processor architecture. This eliminates the need for a separate NVRAM die and its associated bond wires, reducing package complexity while maintaining non-volatile re-writable storage capability.
Solution Approach 2:
The fuse elements serve multiple functions: they provide non-volatile storage, enable re-writable operation through controlled blowing, and can be managed by program instructions. This multi-functional approach replaces what would traditionally require separate NVRAM components, simplifying the overall package structure.
3Reliability
If external NVRAM is used, then non-volatile storage is achieved, but security against unauthorized access is reduced
Solution Approach 1:
By integrating the fuse-based storage directly into the microprocessor architecture, the patent eliminates the external interface that would otherwise exist between external NVRAM and the processor. The storage is now internal and can only be accessed through authorized program instructions, significantly reducing security risks associated with external memory access.
Solution Approach 2:
The fuse blowing device acts as an intermediary that controls access to the fuse elements. Only authorized programs can trigger the fuse blowing device to modify the fuse states, providing a security layer that prevents unauthorized access or modification of the non-volatile storage contents.
Data Source
AI summary
A microprocessor includes re-writeable non-volatile state (RNS) addressable by an instruction executed by the microprocessor that instructs the microprocessor to write a new value to the RNS. A plurality of fuses are each readable to determine whether the fuse is blown or unblown, in response to the microprocessor decoding the instruction. A Boolean logic unit performs Boolean operations on the values read from the plurality of fuses to determine a current RNS value. A fuse blowing device blows at least one unblown fuse to change the current RNS value to the new value when the new value is different than the current value. The microprocessor can read the plurality of fuses, perform the Boolean operations, and blow at least one unblown fuse to change the current value of the RNS to a new value multiple times in response to a program running on the microprocessor executing the instruction multiple times.