PRAM Program-Suspend-Read Control for Interrupted Write Sequences
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Solution Overview
Problem
Phase-change memory cells have slower write times and lower endurance compared to other non-volatile memory technologies, making existing techniques for flash memory devices inapplicable, and simultaneous read and write operations are hindered by the need to restart programming after interruptions.
Innovation Solution
Implement a program-suspend-read operation method for phase-change random access memory (PRAM) devices, where the programming of a write data block is suspended after completing a subset of unit program blocks to allow for a read operation, and then resumed upon completion of the read, using a counter signal to manage the sequence of program pulses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If phase-change memory cells are programmed using conventional methods, then data can be stored, but write times are significantly slower compared to other non-volatile memory technologies
Solution Approach 1:
The programming operation is divided into multiple unit program blocks that can be executed sequentially. The counter signal generates a sequence of program pulses, with each pulse corresponding to a unit program block. This segmentation allows the programming to be paused and resumed without restarting the entire operation, effectively managing the trade-off between write time and endurance.
2Productivity
If simultaneous read and write operations are performed in flash memory, then operational efficiency improves, but the need to restart programming after interruptions increases write time
Solution Approach 1:
The counter signal is prepared in advance to generate the sequence of program pulses. When a read operation interrupts the programming, the counter signal can be resumed from its current state rather than restarting from zero. This preliminary setup of the counter mechanism enables seamless resumption of programming operations, maintaining operational efficiency while minimizing time loss.
3Ease of operation
If the programming operation is interrupted for a read operation, then read access is enabled, but the programming must be restarted from the beginning
Solution Approach 1:
The counter signal provides feedback about the current programming state by tracking which unit program blocks have been completed. This feedback mechanism allows the system to know exactly where to resume programming after an interruption, eliminating the need to restart from the beginning and reducing the time penalty associated with interruptions.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method enables efficient PRAM device operations without significantly affecting endurance or power consumption, allowing for interrupted programming sequences that accommodate read operations without requiring a full restart, thus improving performance and efficiency.
Implementation Method 1
A PRAM, also known as an Ovonic Unified Memory (OUM), includes a phase-change material such as a chalcogenide alloy which is responsive to energy (e.g., thermal energy) so as to be stably transformed between crystalline and amorphous states.
Implementation Method 2
The phase-change material of the PRAM is reset to an amorphous state by joule heating of the material in excess of its melting point temperature for a relatively short period of time.
Data Source
AI summary
A method of performing a program-suspend-read operation in a PRAM device comprises programming a write block comprising N unit program blocks in response to a program operation request, and suspending the program operation after programming M unit program blocks, where M is less than N, in response to a read operation request. The method further comprises executing the requested read operation, and then resuming the programming of the write data block and programming (N−M) remaining unit program blocks.