For many, Kickstart 3.0 and 3.
This marked a significant shift in the operating system's architecture. Kickstart 2.0 introduced the look and feel that most users remember, with improved graphics for the Workbench and better memory management. It was standard on the A500+ and the A600.
The Ultimate Guide to Amiga Kickstart ROMs: Preservation, Emulation, and the Quest for Free Downloads
In the architecture of the Amiga, the Kickstart ROM contained the core of the operating system, AmigaOS. When you switched on an Amiga 500 or 1200, the processor would immediately look to a specific memory address to begin execution. That address was mapped to the Kickstart chip soldered onto the motherboard.
