How to reset them, and what they do. Includes coverage of the SMC functions in T2 chips, and how to reset them too.
SMC
Diagnostic, Recovery, Safe, Startup Manager, Verbose, reset SMC/NVRAM, firmware restore, Target Disk/Display, Single-User (SUM) in outline.
From hardware diagnostics to pmset and resetting the SMC, all you need to know about diagnosing wake and sleep problems.
What should you do with a Mac whose fans keeping coming on full blast, with high CPU loads from kernel_task, and sluggish performance?
Adds details of the sequence of screens displayed at each stage, to help diagnose boot problems.
How did it take Apple so long to tell users of the imminent death of Back to My Mac? And why does Apple replace fully-functional Smart Keyboards?
Single-diagram summary of how a modern Mac starts up in macOS 10.12 or 10.13, from pressing the Power button to running the kernel.
Important info about resetting the NVRAM with a firmware password, and new procedures for resetting the SMC in Macs with T2 chips.
What boot.efi does to prepare to load and run the kernel: building the hardware device tree, handling startup key commands, and more.
The Mac has completed its self-test routines, and now prepares to load the EFI firmware or ‘boot loader’. Where it finds it, what it needs, and how Secure Boot changes this.
The Eclectic Light Company 