Fast RAM, also known as CPU-Only Memory, is expansion memory in Amiga computers that is accessible exclusively by the processor and not by the custom chipset. Unlike Chip RAM, which is shared between the CPU and the Agnus/Alice chip, Fast RAM allows the CPU to access data without waiting for bus arbitration, resulting in significantly faster performance. This memory typically occupies address space starting at 0x00200000 and requires expansion boards, accelerator cards, or CPU upgrades to be added to the system. Fast RAM is essential for running CPU-intensive applications and multitasking operating systems like AmigaOS 2.0 and 3.0 efficiently.