Apple Silicon Under the Hood: ARM64e, Rosetta 2, and the Boot Chain

In 2020 Apple replaced the Mac's Intel processors with its own silicon, and in doing so rebuilt every layer of the platform — from the immutable Boot ROM in the chip to the ARM64e instruction set that userland code compiles against. This book takes you through all of it.It begins with the SoC itself: performance and efficiency cores, GPU, Neural Engine, AMX matrix coprocessor, and the unified memory architecture that removes the PCIe bottleneck between CPU and GPU. From there it covers ARM64e and pointer authentication — the hardware mechanism that makes memory corruption detectable — including the PACIA and AUTIA instruction families, the five cryptographic keys, and the crash signatures that reveal a PAC failure. It walks the boot chain step by step, from Boot ROM through LLB and iBoot to the kernel collection, explaining how each stage verifies the next, how the LocalPolicy encodes the machine's security mode, and how the Secure Enclave signs the policy with a key that never leaves the chip.The second half covers the practical side: Unified Memory and Metal storage modes, the AMX coprocessor and the Accelerate framework, the Neural Engine and Core ML compute units, Rosetta 2's two translation pipelines and its JIT-in-JIT handling, and universal binaries with their fat headers and lipo workflow. Real commands throughout — bputil, csrutil, kmutil, sysctl, lipo, otool, arch, powermetrics — with terminal output you can reproduce on your own machine.Written for systems programmers, security engineers, and anyone who wants to understand why Apple Silicon behaves the way it does.