Power Management

Which describes ACPI, used in PCs and similar systems?

  1. AThe name of a CPU instruction set
  2. BA standard interface between hardware and OS that lets the OS manage device power states, power saving and thermals
  3. CA wireless LAN standard
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Answer: B. A standard interface between hardware and OS that lets the OS manage device power states, power saving and thermals

ACPI (Advanced Configuration and Power Interface) is the standard mechanism by which an OS manages system and device power states. Firmware describes the hardware configuration and how to control power to the OS in tables, which the OS uses to enter sleep (S3) or hibernation (S4), control CPU C-states and P-states, drive fans according to temperature and so on. It also hides hardware-specific differences from the OS.

  • A. It is not an instruction set.
  • B. Correct. It also controls sleep and hibernation.
  • C. It is not a wireless LAN standard.
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More Power Management questions

  1. In smartphone SoCs combining high-performance and efficient cores, why does running light work on the efficient cores use less energy?
  2. Which describes the idea behind adaptive voltage scaling (AVS)?
  3. Which is NOT a reason chips need margin in their supply voltage?
  4. What is an advantage of placing the regulators that generate CPU supply voltages inside the chip or package rather than on the motherboard (integrated regulators)?
  5. Why is the energy-delay product (EDP) sometimes preferred over energy alone in evaluating low-power designs?