In Amiga systems, RAM is divided into Chip RAM, which is accessible by both the CPU and custom chips (Agnus/Alice), and Fast RAM, which is CPU-only and faster. Chip RAM is critical for graphics, audio, and DMA operations, while Fast RAM improves CPU performance by bypassing the slower chip bus. Early Amigas had limited Chip RAM (512KB-2MB), but expansions could add Fast RAM via trapdoor slots or CPU cards.