Memory Controller Variable Latency Acknowledgement
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Solution Overview
Problem
Phase change memory (PCM) devices face limitations in write and read operations due to variable latency periods, restricting their use in memory systems, as they require polling status registers for write operation completion and often suspend write operations for read operations, leading to inefficiencies and restricted operational flexibility.
Innovation Solution
A memory system with a memory controller and operation controller that manages variable latency periods through acknowledgement signals, allowing read and write operations to proceed without timing constraints, enabling flexible operation and concurrent access to memory locations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If phase change memory is used as RAM replacement, then non-volatile memory capability is achieved, but write operation speed deteriorates due to required status monitoring and operation suspension
Solution Approach 1:
The patent applies preliminary action by initiating write operations without waiting for completion confirmation. The system starts the write operation immediately upon receiving the write command, eliminating the need to poll status registers before proceeding with subsequent operations. This approach maintains non-volatile memory reliability while significantly improving write operation speed by removing the time-consuming status monitoring step.
2Measurement precision
If status registers are polled to determine write operation completion, then operational accuracy is maintained, but time consumption increases due to frequent polling requirements
Solution Approach 1:
The patent implements feedback by using an acknowledgment signal mechanism where the memory device automatically sends a completion status back to the controller. Instead of the controller continuously polling status registers, the memory device proactively notifies the controller when write operations complete through feedback signals. This maintains accurate completion detection while eliminating time-wasting polling loops.
3Reliability
If write operations are suspended for read operations, then data integrity is ensured, but operational flexibility deteriorates due to restricted concurrent access
Solution Approach 1:
The patent applies segmentation by dividing memory into multiple independent banks or regions that can operate concurrently. While one memory region performs write operations, other regions can simultaneously perform read operations without interference. This segmentation maintains data integrity within each region while enabling concurrent access across different regions, thereby improving operational flexibility without compromising reliability.
4Reliability
If read operations cannot be performed on memory locations involved in concurrent write operations, then data consistency is maintained, but productivity decreases due to operation restrictions
Solution Approach 1:
The patent introduces an intermediary mechanism in the form of a buffer or cache layer between the controller and memory array. Read operations can access data in the buffer while write operations proceed to the memory array simultaneously. The intermediary buffers data flows, allowing read and write operations to proceed concurrently without directly interfering with each other, thus maintaining data consistency while improving overall productivity.
Data Source
AI summary
Apparatuses and methods for performing memory operations are described. An example apparatus includes a memory operation controller. The memory operation controller is configured to receive memory instructions and decode the same to provide internal signals for performing memory operations for the memory instructions. The memory operation controller is further configured to provide information indicative of a time for a variable latency period of a memory instruction during the variable latency period. In an example method, a write instruction and an address to which write data is to be written is received at a memory and an acknowledgement indicative of an end of a variable latency period for the write instruction is provided. After waiting a variable bus turnaround after the acknowledgement, write data for the write instruction is received.