From Single-Core to Multi-Core: The Evolution of macOS Parallel Processing

The original 128K Mac from 1984 boasted a single 8MHz Motorola 68000 processor, capable of running only one app at a time. Today's Macs, however, comfortably handle multiple substantial apps concurrently, alongside Time Machine backups and other background processes. This article chronicles that evolution, from single-tasking origins to the introduction of Switcher and MultiFinder, the leap to preemptive multitasking and multithreading in Mac OS X, and the performance optimizations brought by Grand Central Dispatch (GCD). The journey culminates in efficient management of up to 32 CPU cores, showcasing Apple's relentless pursuit of performance enhancements in macOS.