Leveraging Transverse Reads to Correct Alignment Faults in Domain Wall Memories

Abstract

Spintronic domain wall memories (DWMs) are prone to alignment faults, which cannot be protected by traditional error correction techniques. To solve this problem, we propose a new technique called derived error correction coding (DECC). We construct metadata from the data and shift state of the DWM, on demand, using a novel transverse read (TR). TR reads in an orthogonal direction to the DWM access point and can determine the number of ones in a DWM. Errors in the metadata correspond to shift-faults in the DWM. Rather than storing the metadata, it is created on-demand and protected by storing parity bits. Repairing the metadata with ECC allows restoration of DWM alignment and ensures correct operation. Through these techniques, our shift-aware error correction approaches provide a lifetime of over 15 years with a similar performance, while reducing area and energy by 370% and 52%, versus the state-of-the-art, for a 32-bit nanowire.