Electrical computers and digital processing systems: support – Computer power control – Power conservation
Reexamination Certificate
1999-07-09
2003-09-09
Lefkowitz, Sumati (Department: 2181)
Electrical computers and digital processing systems: support
Computer power control
Power conservation
C713S310000
Reexamination Certificate
active
06618813
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATION
This application claims the priority benefit of Taiwan application serial no. 87114055, filed Aug. 26, 1998, the full disclosure of which is incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of Invention
The present invention generally relates to a power management method for a computer system, and more particularly to a method for suspending, resuming, and turning on a computer system without being affected by an abnormal power failure.
2. Description of Related Art
With the advancement of information technology, computers play an important role in the day-to-day life in this modern society.
FIG. 1
shows a block diagram of a conventional computer system
100
, which comprises a central processing unit (CPU)
110
, a chipset
120
, a memory
130
, a storage device
140
, an interface device
160
, and a power supply
150
. The CPU
110
is the heart of the computer system
100
, responsible for executing programs in the computer system
100
. The chipset
120
is used to control the communication between other devices within the computer system
100
and the CPU
110
. The memory
130
, typically dynamic random access memory (DRAM) because of its high speed and low cost, is used for storing programs and data for the computer system
100
. The storage device
140
generally has a large capacity for storing data in a longer period, such as a hard disk drive or a compact disc drive, etc. The interface device
160
connected to other peripheral devices is used as an interface for users to access the computer system
100
, including keyboard, mouse, or printer interface, etc. As shown in
FIG. 1
, the interface device
160
including a MODEM
161
connected to a telephone line and a network adapter
162
connected to a network is depicted. The power supply
150
is used to convert an external AC power source into DC voltages, for example, +5V, −5V, +12V, or −12V, etc, required by various circuits within the computer system
100
. For a power supply complying with the newly developed ATX specifications, the output from the power supply comprises a main power and a standby power. When the computer system
100
is in normal operation, the main power provides power for the whole computer system
100
. When the computer system
100
is turned off, the standby power provides power required by some special devices to perform special functions, for example, remote wakeup, keyboard wakeup, or the sleep-state functions which will be described in details hereinafter.
With the advancement in hardware and software of a computer system, an advanced configuration and power interface (ACPI) specification has been developed to provide more functions in power management for the computer system. There are 5 different levels of sleep states, i.e., S
1
~S
5
, defined in the ACPI specification. The S
1
and S
2
sleep states are also called “power on suspend”, which means the main power is still provided by the power supply although the system is in a suspending state. The S
3
sleep state is called “suspend to RAM (STR)”, which means relevant operating information and context of related devices are saved in a memory before the main power is turned off. Nevertheless, the standby power still provides power to the memory and its related circuits, so that relevant operating information and context of related devices can be saved in the memory. The S
4
sleep state is called “suspend to disk (STD)”, which means relevant operating information and context of related devices are saved in a hard disk before the main power is turned off. There is no need for the standby power to provide power to the memory and its related circuits. The S
5
sleep state generally refers to a “soft off” state for the computer system.
Reference is now made to
FIG. 2
, where a flow chart showing a conventional computer system entering into a sleep state or soft-off state is depicted.
FIG. 3
is a flow chart showing a conventional computer system resuming to a normal operation state from a sleep state or soft-off state. As shown in
FIG. 2
, when a suspending or soft-off instruction is received, the computer system determines the instruction category first (Step
21
). If a STR instruction is received, relevant operating information and context of related devices are saved into a memory (Step
22
). The computer system enters into the S
3
sleep state (Step
23
) by turning off the main power, while maintaining the standby power to provide power to the memory and its related circuits to save relevant operating information in the memory. If a STD instruction is received in Step
21
, relevant operating information and context of related devices are saved into a hard disk (Step
24
). The computer system enters into the S
4
sleep state (Step
25
) by turning off the main power. If a soft-off instruction is received in Step
21
, a normal turn-off procedure is performed to close all the application programs. The computer system then enters into the soft-off state (Step
27
).
Reference is now made to
FIG. 3
, where a flow chart of a conventional computer system resuming to a normal operation state from a sleep state or soft-off state is depicted. As shown in
FIG. 3
, when a wake-up instruction, for example, a resuming or turn-on instruction, is received, the computer system checks up the current system state first (Step
31
). If the computer system is in the S
3
or STR sleep state, a STR resuming procedure is performed (Step
32
). That is, relevant operating information and context of related devices saved in the memory are restored to resume the system to its original operating state. Subsequently, the computer system enters the normal operation state (Step
33
). If the computer system is found in the S
4
or STD sleep state in Step
31
, a STD resuming procedure is performed (Step
34
) so that relevant operating information and context of related devices saved in a hard disk are restored to resume the system to its original state. Subsequently, the computer system enters the normal operation state (Step
33
). If the computer system is found in the soft-off state in Step
31
, a normal turn-on procedure is performed (Step
36
). The computer system enters the normal operation state (Step
33
).
When the computer system is in the S
3
or STR sleep state, the computer system can resume to its original operating state in a few seconds. Furthermore, only a portion of the power source, typically less than 5W, is required for the memory and its related circuits to store relevant operating information in the memory while in S
3
state. Compared with a power consumption of 60W~70W in the normal operation state, the S
3
sleep state possesses a significant advantage. As for the S
4
or STD sleep state where relevant operating information are stored in the hard disk, the time frame required is much longer for the system to resume to its original operating state, because a larger accessing time to the hard disk is required. It is therefore apparent that the S
3
is an ideal choice as the sleep state because the computer system not only consumes less power, but also meets requirements of the “on-now system”.
However, there is a risk if the computer system is in the S
3
or STR sleep state. That is, if the external power source is suddenly cut off, the standby power is also cut off. The relevant operating information and context of related devices saved in the memory will be totally lost. The computer system can no longer resumes to its original operating state under this circumstance. The loss of saved data in the memory also causes significant damages to the users.
As mentioned earlier, the power supply provides a main power and a standby power to the computer system. When the main power is turned off, the standby power still provides power to several special devices to perform specific functions. For example, “wake on local area network (LAN)” or “ring in wake up” functions to turn on the computer system, in addition to the S
3
sleep state function m
Hsu Hsien-Yueh
Shiu Long-Loon
Asustek Computrt Inc.
Chung-Trans X.
Lefkowitz Sumati
Rabin & Berdo P.C.
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