CONTROL OF TRANSITIONS BETWEEN POWER MANAGEMENT STATES IN A COMPUTER SYSTEM

摘要

The present invention relates to a computer system having four states of power management: a normal operating state, a standby state, a suspend state, and an off state. A control unit controls transitions between the various states. The standby state is characterized by devices, such as a video controller and a hard drive, being placed into a low-power mode transparent to the operating system and the applications executing on the computer system. The suspend state is characterized by executing code being interrupted and the state of the computer system being saved to a file on the hard drive in such a manner that system power may be removed after the state of the computer system is saved to the hard drive. Later, after system power is restored, the state of the computer system is resumed by reading from the hard drive and loading it in such a manner that the operating system and application programs are not adversely affected. The normal operating state and the off state correspond to the typical on and off states of more conventional computer systems. A single switch causes transitions between the various states. A visual feedback device such as an LED is preferably used to indicate the state of the computer system. While no power management driver is active, the control unit delays state transitions until a suitable power management driver is active.