The ROM acts as the "BIOS" of the Amiga, containing the primary software layers needed before the Workbench (desktop) can load from a disk: The multitasking microkernel.

"Kickstart ROM not found."

The Kickstart 3.0 ROM is exactly (512 KB). Unlike the later Kickstart 3.1 (which could be 512KB or 1MB for CD32), the 3.0 ROM was compact. Commodore engineers managed to pack graphical libraries (Intuition), file systems (AmigaDOS), the Exec multitasking kernel, and hardware abstraction layers into half a megabyte—an incredible feat of assembly language optimization.