Software power control of circuit modules in a shared and distributed DMA system

A system-on-chip integrated circuit selectively gates clocks to individual modules corresponding to the state of a corresponding bit of a peripheral enable register. A reset circuit supplies a signal to a reset input of the digital module for a normal mode if the bit indicates the power-up state and a reset mode if the bit indicates a power-down state. Return to normal mode is delayed a predetermined time after the said bit of indicates the power-up state to ensure clean power up. A false acknowledge circuit for each module supplies an acknowledge signal in response to a received command if the corresponding bit indicates the power-down state.