In plain words: Apple's Neural Engine is the fixed matrix-crunching chip inside its phones and Macs, normally reachable only through Apple's Core ML software. This guide reverse-engineers its inner workings and finds a direct call path that works from ordinary apps but is undocumented and version-fragile.
Abstract
The Apple Neural Engine (ANE) is the fixed-function matrix accelerator that has shipped in Apple systems-on-chip since the A11-class iPhone and iPad chips and the M1-class Mac chips, exposed to applications only through the Core ML model framework. This guide reports a reverse-engineered account of the engine, based on direct measurement on Apple silicon and static analysis of the private runtime, compiler, kernel driver, and firmware. It documents the datapath and the roofline that bound the engine's throughput and energy, the dispatch route that reaches it below Core ML, the compiler and on-disk program format, the weight-compression scheme, and the kernel driver, firmware, and command protocol beneath them. The account covers the A11 through A18 and M1 through M5 families, with per-chip target tables and an operation-by-device matrix; the direct measurements are on the M1 and M5. Claims are labeled as measured, decompile-derived, or predicted, and the methodology and open questions are recorded. The direct route is callable from ordinary user space but remains undocumented, unsupported, and version-fragile; it is intended for measurement, research, and on-device work, not for shipping software, where Core ML remains the supported path.
Spencer H. Bryngelson
arXiv:2606.22283 · cs.AR, cs.OS, cs.PF · submitted Jun 21, 2026
abstract · pdf · html · 302 pages, 12 figures. A reference for the Apple Neural Engine
Really wish this author would blog more, this piece is incredible and includes the code.
Also ModernBERT is amazing if you haven’t used it before, worth spending time with - have used it myself for classification tasks and it’s very impressive.