Memory Controller Locking Standard Flash Memory
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Solution Overview
Problem
Existing handheld computers rely on proprietary flash memory for locking mechanisms, which is expensive due to the proliferation of standard flash memory in consumer devices, making it desirable to use cost-effective standard flash memory instead.
Innovation Solution
A memory controller is implemented on handheld computers to programmatically lock portions of standard flash memory by using a lock status register, control register, and integrated circuit to manage access and modifications, allowing standard flash memory to be used in place of proprietary memory.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If proprietary flash memory is used to implement locking mechanism, then security and access control are ensured, but cost increases
Solution Approach 1:
The memory controller is designed to provide locking functionality that works with standard flash memory, making the controller universal and compatible with both standard and proprietary memory types. This allows the system to use inexpensive standard flash memory while maintaining security through the controller's locking mechanism, thereby reducing cost without sacrificing security.
2Ease of manufacture
If standard flash memory is used to reduce cost, then manufacturing cost decreases, but ability to restrict access to specific portions is lost
Solution Approach 1:
The memory controller acts as an intermediary between the processor and the flash memory. It intercepts access requests and enforces locking constraints by checking the lock status register before allowing access to specific memory portions. This mediator approach enables standard flash memory to provide access control functionality that would otherwise be unavailable, maintaining security while using cost-effective standard memory.
Solution Approach 2:
The flash memory is divided into multiple units, each with its own lock status bit in the lock status register. This segmentation allows individual portions of memory to be locked or unlocked independently, providing fine-grained access control. The controller can restrict access to specific locked units while allowing access to unlocked units, enabling selective protection of critical data without affecting the entire memory space.
3Adaptability or versatility
If locking mechanism is implemented in software, then flexibility is improved, but system complexity increases
Solution Approach 1:
The memory controller automatically manages locking by checking the lock status register and enforcing access restrictions without requiring complex software intervention. The locking mechanism is built into the hardware control logic, which self-manages the protection of locked memory units. This hardware-based approach provides flexibility through programmable locking while minimizing system complexity by automating the protection mechanism at the controller level rather than requiring elaborate software solutions.
Data Source
AI summary
An improved integrated circuit is provided to facilitate communication between a microprocessor and a non-volatile memory. The integrated circuit comprises at least one lock status register, at least one control register and a memory controller. The lock status register comprises a plurality of lock status bits representing whether or not a corresponding unit of storage in the volatile memory has been locked. The control register stores configurable control information for the memory controller, including sizing information defining the size of the unit of storage. The memory controller is configured to receive a modification request to modify data in the non-volatile memory; determine a target unit of storage in the non-volatile memory based on a target memory address associated with the modification request; determine from the lock status register whether the target unit of storage has been locked; and implement the modification request only if the target unit storage has not been locked. A method to be implemented by the circuit is also provided.