Geyser-2: The second prototype CPU with fine-grained run-time power gating

Geyser-2 is the second prototype MIPS CPU which provides a fine-grained run-time power gating (PG) controlled by instructions. Geyser-1[1], the first prototype only provides the fine-grained run-time PG core. Although it demonstrated the leakage power reduction on a real chip, the operational frequency is limited at 60MHz because of the limitation of the I/O speed. Geyser-2 with cache and TLB mechanism is implemented to show (1) run-time PG works at least with 200MHz which is commonly used clock for embedded systems, and (2) it is also efficient on the environment with real application programs with an operating system.