Apple Certified Support Professional (ACSP) Practice Exam 2025 - Free ACSP Practice Questions and Study Guide

The first stage of the macOS (formerly OS X) system startup procedure is the firmware. This stage is responsible for the initial hardware checks and device initialization when the computer is powered on. The firmware resides in a read-only memory chip on the motherboard and loads the bootloader, which is a critical component that starts the operating system process.

Firmware performs essential tasks, such as performing POST (Power-On Self-Test) checks to ensure that the hardware components are functioning properly before proceeding to load the operating system. After the firmware completes its checks, it hands over control to the bootloader, which is the next phase in the startup process, leading then to the loading of the kernel and other system components.

Each of the other options represents a subsequent stage in the startup process: the booter and launchd are involved in loading the operating system and starting system processes, while the kernel is the core part of the operating system that manages resources and the hardware once it is loaded. Understanding the sequence of these stages is vital for grasping how macOS initializes and operates.