U.S. patent number 6,216,187 [Application Number 08/984,118] was granted by the patent office on 2001-04-10 for system for powering down a portable computer in a docking station.
This patent grant is currently assigned to Toshiba America Information Systems, Inc.. Invention is credited to Cuong Cam Truong.
United States Patent |
6,216,187 |
Truong |
April 10, 2001 |
System for powering down a portable computer in a docking
station
Abstract
A method of powering down a computer system when the operating
system is running. According to the method, it is determined when
the computer system is to be powered down and if power management
mode is enabled. If the power management mode is enabled and the
computer system is not docked with a docking station, the computer
system is powered down by saving the system state and then removing
power from the computer system's processing unit. Alternatively, if
the power management mode is enabled and the computer system is
docked, the computer system is powered down by placing the computer
system in a mode in which the keyboard and display are locked. In
one embodiment, the computer system is powered down when the power
management mode is disabled by causing the operating system to exit
and then removing power from the computer system. A portable
computer that includes the system for powering down of the present
invention is also provided.
Inventors: |
Truong; Cuong Cam (Tustin,
CA) |
Assignee: |
Toshiba America Information
Systems, Inc. (Irvine, CA)
|
Family
ID: |
25530327 |
Appl.
No.: |
08/984,118 |
Filed: |
December 1, 1997 |
Current U.S.
Class: |
710/304;
710/303 |
Current CPC
Class: |
G06F
1/1632 (20130101); G06F 1/26 (20130101) |
Current International
Class: |
G06F
1/16 (20060101); G06F 1/26 (20060101); G06F
013/00 () |
Field of
Search: |
;395/281-283,750.02,750.05,750.06,750.07 ;361/868,683 ;710/101-103
;713/310,323,324,330 |
References Cited
[Referenced By]
U.S. Patent Documents
Other References
Intel Corporation/Microsoft Corporation; Advanced Power Management
(APM) BIOS Interface Specification, Revision 1.2, Feb.
1996..
|
Primary Examiner: Beausoliel, Jr.; Robert W.
Assistant Examiner: Phan; Raymond N
Attorney, Agent or Firm: Pillsbury Winthrop LLP
Claims
What is claimed is:
1. In a computer system having a docking station and a portable
computer adapted to be mechanically and electronically engaged with
the docking station, the portable computer having an operating
system, the portable computer having an actuator for enabling a
user to disengage the portable computer from the docking station,
the improvement comprising a utility program encoded on a memory
which is executable in response to selection of the actuator, the
utility program including:
logic executable on the portable computer for detecting whether the
portable computer is engaged with the docking station;
logic executable on the portable computer for detecting an ejection
signal transmitted in response to a user selection of the actuator
for disengaging the portable computer from the docking station;
and
logic executable on the portable computer for generating a message
on a display to instruct termination of the operating system prior
to disengaging and for preventing any disengagement of the portable
computer from the docking station in response to the ejection
signal when the portable computer is engaged with the docking
station while the operating system is executing until the user
manually selects to terminate execution of the operating
system.
2. The computer system of claim 1, wherein the portable computer
further includes a display, and wherein the utility program further
includes logic for initiating a placement of a message on the
display in response to the ejection signal when the portable
computer is engaged with the docking station while the operating
system is executing.
3. The computer system of claim 1, wherein the message on the
display provides a prompt to a user for powering down the portable
computer before initiating disengagement of the portable computer
from the docking station.
4. A computer readable medium encoded with a program for execution
on a portable computer, the portable computer being adapted to be
mechanically and electronically engaged with a docking station, the
portable computer having an operating system and an actuator for
enabling a user to disengage the portable computer from the docking
station, the program including instructions for performing the
steps of:
detecting whether the portable computer is engaged with the docking
station;
detecting an ejection signal transmitted in response to a user
selection of the actuator for disengaging the portable computer
from the docking station; and
generating a message on a display to instruct termination of the
operating system prior to disengaging and preventing any
disengagement of the portable computer from the docking station in
response to the ejection signal when the portable computer is
engaged with the docking station while the operating system is
executing until the user manually selects to terminate execution of
the operating system,
wherein the program is a utility program adapted for storing on a
memory of the portable computer, and wherein the utility program is
configured to respond to an interrupt initiated upon a selection of
the actuator.
5. The computer readable medium of claim 4, wherein the portable
computer further includes a display, and wherein the utility
program further includes logic for initiating a placement of a
message on the display in response to the ejection signal when the
portable computer is engaged with the docking station while the
operating system is executing.
6. The computer readable medium of claim 5, wherein the message on
the display provides a prompt to a user for powering down the
portable computer before initiating disengagement of the portable
computer from the docking station.
Description
FIELD OF THE INVENTION
The present invention relates to a system for powering down a
portable computer, and more specifically to a system that reliably
and efficiently powers down a portable computer having a power
saving mode.
BACKGROUND OF THE INVENTION
In conventional computer systems, a user initiates a powering down
of the system by pressing an on/off switch. In response, the system
is typically powered down by simply cutting power to the system.
When power is removed from the system, the contents of registers
and memory locations associated with the system's microprocessor
and peripheral devices are generally lost. When power is later
restored to power up the system, an initialization routine must be
executed to place the system in a known initial state. In
particular, any operating system and application programs that were
running on the system prior to power down must be reloaded and
restarted. Besides creating a long delay before the computer system
is restored to its previous operating state, such conventional
powering down can cause unsaved data associated with the operating
system and/or application programs to be lost. This loss of data
may result in a loss of some or all of the user's work product, and
may even cause the computer system to crash or run improperly on
the subsequent power up.
Portable computer systems such as laptops and notebooks comprise a
quickly growing segment of the commercial market for computers.
Portable computers are typically self-contained systems that can be
operated on battery power in situations where the user does not
have access to an AC power source (e.g., in an airplane or on a
bus). System designers have been working to reduce the power
consumption of portable computer systems in order to maximize the
operating life of the system when running on battery power. In this
regard, various techniques have been devised for reducing power
consumption by manipulating clock signals and/or power supplies
with respect to inactive circuit portions. Typically, a power
management unit detects or predicts inactive circuit portions and
accordingly turns off the clock signals that drive the inactive
circuit portions in order to decrease the overall power consumption
of the system. Similarly, the frequency of clock signals can be
reduced during operations that are not time critical, and power can
be removed from inactive circuit portions.
The Advanced Power Management (APM) system is a standardized power
reduction system for use with personal computers. The definition of
the APM standard can be found in "Advanced Power Management (APM)
BIOS Interface Specification" (Rev. 1.2, February 1996), which is
published by Intel Corporation (Santa Clara, Calif.) and Microsoft
Corporation (Redmond, Wash.) and is herein incorporated by
reference. Computer systems that operate in accordance with the APM
standard allow the operating system to initiate idle calls to
determine whether various application programs are busy or idle. In
response to an idle call, each application program returns an idle
indication to the operating system if it is idle. If all
application programs running on the system return an idle
indication, the operating system passes the all-idle indication to
the system BIOS (Basic Input/Output System). The BIOS may then take
power reduction steps such as reducing the frequencies of selected
clock signals and/or removing power from selected inactive circuit
portions. If any application program later becomes active, the
system BIOS exits the reduced power state by causing the clock
signals to return to their normal levels and/or power to be
reapplied to the various circuit portions.
In more detail, the APM system defines four power management
states: a normal operating state, a standby state, a suspend state,
and an off state. The APM power management driver (APM driver) runs
in the background (i.e., in the BIOS and the operating system) so
it is transparent to the user. The portion of the APM driver in the
operating system (APM OS driver) is present in operating systems
such as the Windows 95.TM. operating system sold by Microsoft
Corporation, and the portion of the APM driver in BIOS (APM BIOS
driver) is provided by the system designer. The APM OS driver and
the APM BIOS driver communicate with one another so as to operate
together (i.e., as the APM driver) to control the computer's
transition between the four APM states. Typically, state
transitions are handled by the APM driver based on the states of a
switch, a flag, an activity timer, a wake alarm, and/or a ring
detector.
The normal operating state is virtually identical to the normal
operating state of a computer system that does not perform power
management. Likewise, the off state is virtually identical to the
powered down state of a conventional computer system. In the off
state, the power supply does not provide any power, and the state
of the computer system prior to entering the off state is lost. In
addition to the normal and off states, the APM standard defines two
reduced power states--the standby and suspend states.
The standby state uses less power than the normal operating state,
yet leaves any applications executing as they would otherwise
execute. In general, power is conserved in the standby state by
placing devices into low-power modes of operation (e.g., by ceasing
the revolutions of the hard disk and by ceasing generation of the
video signal). In contrast, when the computer system is in the
suspend state, an extremely small amount of power is consumed. Such
low power consumption is obtained by saving the state of the
computer system to the hard drive and then turning "off" the power
supply.
To enter the suspend state, the computer system must interrupt any
executing code and transfer control to the APM driver, which
ascertains the state of the computer system and writes the state to
the hard disk (or RAM that does not lose power). In particular, the
state of the CPU registers, the CPU cache, the system memory, the
system cache, the video registers, the video memory, and the other
devices' registers must all be saved to the hard disk. In other
words, the entire state of the system is saved so that it can be
restored without the executing application programs being adversely
affected by the transition to suspend mode. The suspend condition
is then indicated in non-volatile memory, and power is removed from
the system. Thus, the state of the system is saved to the hard
disk, system power is "off," and only a small amount of power is
consumed by circuitry that monitors for events that cause the
system to "wake-up" from the suspended state.
While such power management features have made portable computers
more popular, many users desire a portable computer that has the
same capabilities as a desktop computer. For such users, the
expense of purchasing a second computer system for its portability,
in addition to a fully functional desktop computer system, is
difficult to justify. In effect, the user would own two nearly
identical computer systems, only one of which is usually operating
at a time. In order to provide a fully capable yet portable
computer system, portable computers have been developed that can be
coupled to a separate stationary unit. For example, the stationary
unit may include features such as additional storage capacity
(e.g., a large hard drive), additional display capabilities (e.g.,
a larger CRT display), and additional input capabilities (e.g., a
larger keyboard). Such a stationary unit is known as a "docking
station." The docking station usually is kept in one location and
remains coupled to local area networks, the telephone system,
peripherals, and an AC power source. After docking the portable
computer, the user can access these resources.
In some conventional docking stations, the method of coupling the
portable computer to the docking station uses a mechanical system
(e.g., a latch system) that mates the computer and docking station.
With such a station, undocking can be performed while an
application is running on the system, but this will cause the
system to crash and unsaved data to be lost. In more sophisticated
docking stations, the portable computer and docking station are
coupled together using a mechanically triggered electromechanical
docking/undocking mechanism. This type of station increases the
reliability of the interconnection through mechanical and
electrical interlocks and prevents undocking in undesirable
situations (e.g., when an application is running on the
system).
While some conventional docking stations can lessen the chance of
data loss by preventing undocking when the computer system is
turned on, data may still be lost with such systems if the user
powers down the system while the operating system is still running.
In conventional systems, when the user presses the power switch,
power is almost immediately removed from the computer system
regardless of whether any software (i.e., operating system or
application programs) is running on the system. Thus, unsaved data
associated with the running operating system and application
programs (e.g., the user's work product and important system data)
can be lost. Further, saved data is typically stored in write
buffers for a period before being written to disk, so the user may
actually lose data that was believed to be saved. Similarly, if
data is still being written to the disk when power is removed, the
user's file may be corrupted and become unreadable. Additionally,
conventional portable computer systems are powered down in the same
manner when docked and undocked.
SUMMARY OF THE INVENTION
In view of these drawbacks, it is an object of the present
invention to remove the above-mentioned drawbacks and to provide a
system that reliably and efficiently powers down a portable
computer having a power saving mode. The power down system
determines the best system shut down sequence that will prevent
data loss based on whether the portable computer is docked or
undocked and whether the power saving mode is enabled or disabled.
The chosen shut down sequence ensures that before power is removed
from the computer system, either: the operating system and all
application programs are exited; or the current state of the system
is made recoverable. Thus, before power is removed, data associated
with the running operating system and application programs is saved
and the operating system is given the chance to flush all write
buffers so that system and user data is not lost and files are not
corrupted. In this manner, the shut down system of an embodiment of
the present invention lessens the chance of data loss when the
system is powered down.
According to a first embodiment of the present invention, a method
of powering down a computer system is provided. According to the
method, it is determined when the computer system is to be powered
down and whether power management mode is enabled. If the power
management mode is enabled and the computer system is not docked
with a docking station, the computer system is powered down by
saving the system state and then removing power from the computer
system's processing unit. Alternatively, if the power management
mode is enabled and the computer system is docked, the computer
system is powered down by placing the computer system in a mode in
which the keyboard and display are locked. In one preferred
embodiment, the computer system is powered down when the power
management mode is disabled by causing the operating system to exit
and then removing power from the computer system.
According to a second embodiment of the present invention, a
portable computer that can be docked with a docking station is
provided. The portable computer includes a CPU, RAM, at least one
peripheral device, and a power switch for powering the portable
computer up and down. Additionally, the portable computer includes
power management circuitry that selectively reduces power
consumption, and a power management enable switch that controls the
power management circuitry. When the portable computer is powered
up and the power switch is activated, the portable computer is
powered down in a manner dependent on the current state of the
system. If the power management circuitry is enabled and the
portable computer is not docked, the system state is saved and then
power is removed from the CPU. If the power management circuitry is
enabled and the portable computer is docked, the keyboard and
display are locked. In one preferred embodiment, if the power
management circuitry is disabled, the portable computer is powered
down by exiting the operating system and then removing power from
the portable computer.
Other objects, features, and advantages of the present invention
will become apparent from the following detailed description. It
should be understood, however, that the detailed description and
specific examples, while indicating preferred embodiments of the
invention, are given by way of illustration only and various
modifications may naturally be performed without deviating from the
present invention.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a block diagram of a portable computer system;
FIG. 2 is a diagram of a power management system for the portable
computer of FIG. 1;
FIG. 3 is a flow chart for an undocking protection system; and
FIG. 4 is a flow chart for the powering down system of a preferred
embodiment of the present invention.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
Preferred embodiments of the present invention will be described in
detail hereinbelow with reference to the attached drawings.
FIG. 1 shows a block diagram of a portable computer system 10. As
shown, the portable computer system includes a central processing
unit (CPU) 20 that is connected by a system bus 30 to a random
access memory (RAM) 22, a BIOS memory 24, and a hard disk 26. An
internal, battery-backed, clock (i.e., a real-time clock) 28, which
includes a memory for storing the current date and time, is coupled
to the BIOS memory 24. When the system is booted, the BIOS is used
to configure the system in accordance with the data in a setup
memory and the hardware devices that are coupled to the system.
During system operation, the portable computer 10 runs an operating
system that facilitates communication between application programs
and the BIOS. In one embodiment, the operating system is a version
of the Windows.TM. operating system sold by Microsoft Corporation.
The Windows.TM. operating system is stored on the hard disk and is
loaded into the computer system during the boot-up procedure. When
started, the operating system sets various system parameters based
on the system configuration, and stores these parameters in a
configuration file that is accessed by the application programs.
Because the BIOS configures the system at boot-up and the operating
system sets system parameters at startup based upon the
BIOS-generated system configuration, new peripheral devices cannot
be added to the system after boot-up. In other words, the system
does not provide "plug-and-play" capabilities. In order to use a
new peripheral device with the system, the system must be re-booted
(after connecting the device) so that the BIOS can configure the
system in such a way as to define an interface with the new
peripheral device.
The operating system also maintains a "clock" for displaying date
and time information on the portable computer. In particular, date
and time information is retrieved from the real-time clock when the
operating system is initialized. The operating system stores this
initial date and time information in the RAM, and then keeps track
of the time by incrementing the stored values using an internal
clock signal. While the operating system is running, the current
date and time information stored in the RAM is used by the
operating system to display the time for the user and to time-stamp
activities.
In addition to the operating system, the system software includes
device drivers that support peripheral devices such as a sound
card, a network adapter, and a CD-ROM drive. The device drivers
execute on the CPU in response to hardware interrupts initiated by
the corresponding peripheral devices. During execution of one of
the device drivers, several values relevant to the operation of the
corresponding device (e.g., data to be processed and program
counter value) may be stored in the general registers of the CPU.
Additionally, the drivers may transfer data between the peripheral
devices and the system RAM.
FIG. 2 shows a diagram of the power management system in the
portable computer of FIG. 1. The power management features of the
computer system include support for the Advanced Power Management
(APM) system. As explained above, the APM system (through the APM
driver) can transition the system between several states in order
to reduce power consumption. In a preferred embodiment, an APM
switch is provided on the portable computer to allow the user to
enable or disable the APM system features. When initially powered
up (S10), the computer system is booted and all hardware components
receive full power. In this state, the computer system is said to
be "full-on" (S12). If the APM switch is set so that the APM
features are disabled (S14), the portable computer remains in the
full-on state until the user powers down the system. This is known
as the "boot mode" of operation (S16).
On the other hand, if the APM features are enabled by the APM
switch (S14), the portable computer is in the "power saving mode"
of operation (S24). In the power saving mode, the APM features are
enabled so that the APM driver transitions the system between the
normal (full-on) operating state (S18), the standby state (S20),
and the suspend state (S22) on the basis of system activity. More
specifically, after a specified period of system inactivity (e.g.,
when no interrupts are initiated by peripheral devices), the
computer system transitions from the normal operating state (S18)
to the standby state (S20), and then after another specified period
of inactivity, the system transitions from the standby state (S20)
to the suspend state (S22).
In the transition to the suspend state (S22), the contents of the
general registers of the CPU are saved in the RAM and then power is
removed from the CPU and other components, with the notable
exception of the RAM that stores the state of the CPU.
Additionally, the system software calls the device drivers to
notify them of the transition to the suspend state (S22). When
called, the device drivers operate to store relevant information in
the RAM so that the drivers will not have to be re-initialized when
the system transitions back to the normal operating state (S18).
Thus, a driver that was executing when the system entered the
suspend state (S22) can use the stored values to allow processing
to continue from the point at which processing was suspended. In
further embodiments, the system information is stored on the hard
disk as explained above.
When the system is in the suspend state (S22) and a wake-up event
occurs (e.g., an interrupt is generated in response to mouse
movement, keyboard use, or other peripheral device input), the APM
driver returns the computer system to the normal (full-on)
operating state (S18). Specifically, power is restored to the CPU
and other components, and the contents of the general registers of
the CPU, which were stored in the RAM, are reloaded so that
execution can resume from the point at which it was suspended upon
the state transition. Additionally, the date and time information
that is maintained in the RAM is not updated while the system is in
the suspend state (S22). Therefore, the system software must
re-initialize the operating system "clock" by re-retrieving the
date and time information from the real-time clock. This allows the
proper time to be displayed after the return to the normal
operating state (S18).
The portable computer system 10 also includes a docking feature
that allows the user to mechanically and electronically engage the
portable computer with a docking station. In a preferred
embodiment, the docking station directly couples the portable
computer with a network, an additional storage device, a CRT
monitor, and a standard size (i.e., desktop-type) keyboard. In
order to dock the portable computer with the docking station, the
portable computer is inserted into the docking station and is then
booted up (or re-booted) so that the BIOS can configure the system
to include the connection with the docking station. Once booted,
the computer system can be used in the normal manner and the
additional capabilities offered by the docking station can be used.
Further, when the portable computer is docked with the docking
station, the portable computer can be put into an "instant security
mode" in which the keyboard and display are locked. That is, the
keyboard does not generate any input and the display is
blanked.
To undock the portable computer from the docking station, the user
presses an eject switch that performs the operations necessary to
disconnect the computer system from the network and mechanically
disengage the portable computer from the docking station. That is,
the activation of the eject switch generates an interrupt, and the
interrupt causes a utility program to begin the undocking
procedure. In a preferred embodiment, the portable computer system
does not have "plug-and-play" capabilities so the portable computer
will not finction properly after being undocked until the system is
re-booted to allow the BIOS to remove the connection with the
docking station. Therefore, if the user presses the eject switch
while the portable computer is docked and the operating system is
running, the system software prevents the portable computer from
undocking.
The undocking protection system is shown in greater detail in the
flow chart of FIG. 3. The system software includes an undocking
utility program that is executed when the operating system is
active and an interrupt is generated by the eject switch (step
S40). The program first checks the configuration file to see if the
portable computer is docked (step S42). If the portable computer is
docked, the program does not initiate the undocking procedure but
instead displays a message on the display (step S46). The message
advises the user that the operating system does not have
"plug-and-play" capabilities and that the machine must be powered
down before the portable computer can be undocked. On the other
hand, if the configuration file indicates that the portable
computer is not docked, the program displays a message that the
devices at the docking station will not be recognized (i.e.,
usable) until the system is re-booted (step S44). In either case,
after displaying the appropriate message, the program gives the
user the option of exiting the operating system and shutting down
the system (step S48).
FIG. 4 shows a flow chart for an embodiment of the system for
powering down. To initiate a powering down of the computer system,
the user presses the power switch. However, because data may be
lost and files corrupted if the system is powered down while the
operating system is running, the system software prevents power
from being removed from the system while the operating system is
running. That is, the system software includes an exit utility
program that executes when the operating system is active and an
interrupt is generated in response to the power switch. The exit
program determines how to shut down the system when the power
switch is pressed based on: 1) whether the portable computer is
docked or undocked; and 2) whether the portable computer is in the
power saving mode or the boot mode.
More specifically, when the computer is running and the power
switch is pressed (step S70), the BIOS generates an interrupt. This
interrupt is trapped and rejected so as to disable an immediate
power down, and then the exit program is launched. The exit program
checks the configuration file to determine whether the portable
computer is docked or undocked, and checks the BIOS to determine
whether the computer is in the boot mode or the power saving mode
(step S72). If the portable computer is in the boot mode, a message
is displayed to notify the user that the operating system must be
exited before the system can be powered down (step S74). After
notifying the user, the program generates an exit call to the
operating system (step S76). In response, the operating system
closes all application programs that are running and then shuts
itself down.
After the operating system has been properly shut down, the exit
program calls the power system to power down the portable computer
(step S78). In further embodiments, the exit program generates an
"exit and power down" call to the operating system, which then both
exits and powers down the computer. When in the boot mode, this
sequence of operations is performed because activation of the power
switch with the power saving features disabled indicates a desire
to completely power down the system without saving the current
operating state. Therefore, after the operating system and all
application programs are properly exited so that data loss is
avoided, power is completely removed from the system.
Alternatively, if the portable computer system is in the power
saving mode and is undocked, the exit program transitions the
portable computer to the suspend state. As explained above, such a
transition includes calls to all device drivers to notify them of
the upcoming transition to the suspend state (step S82). In
response, the device drivers can store relevant information so that
the drivers will not have to be re-initialized when the system
transitions back to the normal operating state. For example, a call
to the device driver for a PCMCIA card enables the driver to save
relevant operating information before the card is powered down.
After all relevant CPU and peripheral device information is stored
(step S84), the exit program puts the portable computer into the
suspend state (step S86), which consumes an extremely small amount
of power. On the other hand, if the portable computer system is in
the power saving mode and is docked, the exit program places the
computer system in the instant security mode (step S88). As
explained above, this locks the keyboard and display so that the
keyboard does not generate any input and the display is
blanked.
When in the power saving mode, these sequences of operations are
performed because activation of the power switch with the power
saving features enabled indicates a desire to enter the suspend
state, from which the current state can be recovered. Thus, if the
portable computer is docked, the system is connected to an AC power
source so the keyboard is displayed and the display is blanked.
This allows the CPU and all peripheral devices to remain in their
current state for a quick and flawless restart, while preventing
the loss of any data. Additionally, if the system remains locked
and inactive for a specified period, the APM driver or BIOS may
power down unused peripherals or transition the system to the
suspend state. Similarly, if the portable computer is undocked, the
system may not be connected to an AC power source so the suspend
state is entered immediately. This effectively removes system power
and allows the system to later return to the current state, while
preventing the loss of any data.
After being shut down by the exit program, the system is restarted
when the user again presses the power button. In particular, if
power was completely removed from the system (i.e., system was in
boot mode), the system is restarted by applying power and
re-booting the system. If the system was put into the suspend state
(i.e., system was in power saving mode and undocked), the system is
restarted by returning it to the normal (full-on) operating state
in the manner described above. If the system was put into the
instant security mode (i.e., system was in power saving mode and
docked), the system is restarted by exiting from the instant
security mode to unlock the keyboard and display (assuming that the
system was not also put into the suspend state).
As previously explained, the present invention provides a system
that reliably and efficiently powers down a portable computer
having a power saving mode. The power down system determines the
appropriate system shut down sequence that will prevent data loss
based on whether the portable computer is docked or undocked and
whether the power saving mode is enabled or disabled. Embodiments
of the present invention ensure that before power is removed
either: the operating system and all application programs are
exited; or the current state of the system is made recoverable.
This lessens the chance of data loss by preventing the system from
simply removing power to the system while the operating system is
running. In particular, before power is removed, data associated
with the running operating system and application programs is saved
and the operating system is given the chance to flush all write
buffers so that system and user data is not lost and files are not
corrupted.
The embodiments of the present invention described above relate to
systems that do not have "plug-and-play" capabilities running the
Windows.TM. operating system. However, the power down system of the
present invention could be implemented with other operating systems
or on computer systems that do provide "plug-and-plug" or other
features. Similarly, while the above embodiments are described in
relation to the APM system of power management, other types of
power management systems with varying features and abilities could
be used in conjunction with the power down system of the present
invention. Additionally, other design choices, such as the computer
system's architecture, the connected peripheral devices, and the
features and additional capabilities of the docking station could
easily be adapted. Furthermore, embodiments of the present
invention may not include all of the features described above. For
example, the system software may not maintain its own time and date
information in RAM and the system software may not prevent
undocking when the operating system is running in all
embodiments.
While there has been illustrated and described what are presently
considered to be the preferred embodiments of the present
invention, it will be understood by those skilled in the art that
various other modifications may be made, and equivalents may be
substituted, without departing from the true scope of the
invention. Additionally, many modifications may be made to adapt a
particular situation to the teachings of the present invention
without departing from the central inventive concept described
herein. Therefore, it is intended that the present invention not be
limited to the particular embodiments disclosed, but that the
invention include all embodiments falling within the scope of the
appended claims.
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