Motorola Mobility, Inc. v. Apple, Inc.

Filing 218

AFFIDAVIT signed by : Jill Ho. re 217 Response in Opposition to Motion Declaration of Jill Ho in Support of Apple's Opposition (D.E. 217) by Apple, Inc. (Attachments: # 1 Exhibit A, # 2 Exhibit B, # 3 Exhibit C, # 4 Exhibit D, # 5 Exhibit E, # 6 Exhibit F, # 7 Exhibit G, # 8 Exhibit H, # 9 Exhibit I, # 10 Exhibit J, # 11 Exhibit K, # 12 Exhibit L)(Pace, Christopher)

Exhibit J

111111111111111111111111111111111111111111111111111111111111111111111111111
US006282646Bl

United States Patent

(10)

Hendry et al.

(12)

(45)

(54)

Inventors: Ian Hendry, San Jose; Eric Anderson,
Los Gatos, both of CA (US); Fernando
Urbina, Colorado Springs, CO (US)

5,682,529 * 10/1997 Hendry et al.
5,825,359
10/1998 Derby et al.

SYSTEM FOR REAL-TIME ADAPTATION TO
CHANGES IN DISPLAY CONFIGURATION

(75)

(73)

Assignee: Apple Computer, Inc., Cupertino, CA
(US)

( * ) Notice:

Subject to any disclaimer, the term of this
patent is extended or adjusted under 35
U.S.c. 154(b) by 0 days.

(21)

Appl. No.: 09/074,300

(22)

Filed:

(51)
(52)
(58)

Int. CI?
U.S. Cl.
Field of Search

May 8, 1998
G06F 1/24
713/100
713/100; 710/8,
710/10,17,46,47,48; 714/5, 7

References Cited

(56)

U.S. PATENT DOCUMENTS
5,014,193
5,276,630
5,282,268
5,469,223

*
*
*
*

5/1991
1/1994
1/1994
11/1995

Garner et al.
Baldwin et al.
Mieras et al.
Kimura

14

_____

364/200
364/505
395/164
348/581

__-

395/653
345/344

* cited by examiner
Primary Examiner-William Grant
Assistant Examiner-Ronald D. Hartman, Jr.
(74) Attorney, Agent, or Firm-Burns, Doane, Swecker &
Mathis, L.L.P.
ABSTRACT

(57)

A hot-plugging capability for video devices is achieved by
shifting the responsibility for recognizing changes in the
configuration of a display environment from a computer's
operating system to a device manager. When an input/output
device is added to or removed from the computer system, an
interrupt signal informs a device manager of the fact that a
change in configuration has occurred. In response thereto,
the device manager determines whether the changed component relates to the computer's display function. If so, the
device manager makes a call to the computer's display
manager, to inform it of the fact that the display configuration has changed. In response to this call, the display
manager reconfigures the display space for the computer
system and notifies clients as appropriate, to accommodate
display features associated with the added component. With
this change in the configuration of the display space, the
added component becomes immediately available for use.
33 Claims, 3 Drawing Sheets

26

VIDEO
CARD
~------~VIDEO
DRIVER

Patent No.:
US 6,282,646 BI
Date of Patent:
Aug. 28, 2001

12

DISPLA Y
10
-~------~--_s=
13

16

DISPLAY
MANAGER

18

OPERA TING SYSTEM

APPLICA TIONS

20

u.s.

Patent

FIG. 1

26

74
VIDEO
CARD

US 6,282,646 BI

Sheet 1 of 3

Aug. 28, 2001

72

.....------1

DISPLA Y
_________ ~----~---s= 70

VIDEO
DRIVER

DISPLAY
DRIVER

73

76
DISPLAY
MANAGER

22

78

OPERA TING SYSTEM

APPLICA TIONS

38

20

FIG. 2

36

30
32

34
40
/

"

u.s. Patent

Aug. 28, 2001

US 6,282,646 BI

Sheet 2 of 3

APPLICA TIONS

20

FIG. 4
TO
OJSPLAY

46

SENSOR ~

IRQ
IRQ

PC CARD

44/

1
I

~
DEVICE
MANAGER
~

DISPLAY
MANAGER

rv- 48
.-r- 22

OPERA TING SYSTEM

u.s.

Patent

Aug. 28, 2001

Sheet 3 of 3

US 6,282,646 BI

YES

NO

YES
NO TIFY DISPLA Y
MANAGER OF
ADDITION

YES

54

NOTIFY DISPLA Y
MANAGER OF
REMOVAL

68

56
REGISTER DEVICE

REMOVE DEVICE

58
ASSIGN BUFFERS

NOTIFY/LAUNCH
PROGRAMS

70

60

72

62

DELETE BUFFER
ASSIGNMENT

64

RESTORE
PREFERENCES

UPDATE OLD &
RESTORE NEW
PREFERENCES

NOTIFY
PROGRAMS

REBUILD RESOURCES

CONTINUE

FIG. 5

US 6,282,646 Bl
1

2

As the capabilities offered by personal computers continue to expand, the opportunities for changing the configuration of computers grows in a concomitant manner. In some
FIELD OF THE INVENTION
situations, users may desire to have changes in the configuThe present invention is directed to computer display 5 ration of the computer's display environment become
instantaneously effective, without the need to restart the
systems, and more particularly to a display system which is
computer or even place it in a sleep mode. For example, the
capable of instantaneously accommodating changes in the
user may create a slide presentation on a notebook computer.
configuration of a computer system.
During the course of a meeting, a user may desire to
10 immediately display the slide presentation, by connecting
BACKGROUND OF THE INVENTION
the computer to a suitable video projector, or the like. It is
As computers become more prevalent in everyday use,
desirable to be able to carry out this operation without the
particularly personal type computers, users are employing
need to first put the computer to sleep, and thereby reduce
them in a variety of different situations. Depending upon the
the time needed to operate within the changed configuration.
particular situation, the user may desire to change the
15 It is an objective of the present invention, therefore, to
configuration of the display devices connected to the comexpand upon the capabilities of the system of the '529
puter. For example, portable computers of the so-called
patent, by providing a display environment in which
laptop or notebook type have become increasingly popular
so-called "hot plugging" of displays is possible, wherein a
because of their small size and light weight, making them
display becomes immediately available for use as soon as it
suitable for use while traveling. Due to the need to keep their
20 is plugged into the computer system.
dimensions to a minimum, the display screens built into such
computers are relatively small in size, and may offer only
SUMMARY OF THE INVENTION
limited display capabilities. Therefore, when using one of
In accordance with the present invention, the foregoing
these types of computers in an office environment, the user
may connect it to a monitor having a larger display area 25 objective is achieved by utilizing a device manager to
automatically recognize and react to changes in the configuand/or enhanced display capabilities. Such a connection
ration of a display environment, rather than wait for the
might be made, for example, by means of a docking station
computer's operating system to proactively determine the
which enables the portable computer to be conveniently
status of the display environment, for example upon restartconnected to a variety of peripheral devices, or by inserting
30 ing. When an input/output device is added to or removed
a video card in a PC Card slot.
from the computer system, an interrupt signal informs the
Subsequently, the user might remove the added monitor,
device manager of the fact that a change in configuration has
for example to take the computer home or to use it while
occurred. In response thereto, the device manager detertraveling. In this situation, the built-in display screen must
mines whether the changed component relates to the combe used. In other words, the computer must route all information to be displayed to the built-in screen, rather than the 35 puter's display function. For example, it may determine
whether an added device is a video card. If so, the device
port to which the external monitor was connected. In
manager makes a call to the computer's display manager, to
addition, the displayed information must be reformatted, or
inform it of the fact that the display configuration has
otherwise processed, to accommodate the display paramchanged. In response to this call, the display manager
eters of the built-in device.
In the past, changes in the configuration of the computer 40 reconfigures the display space for the computer system, to
accommodate an additional frame buffer that is associated
system, such as the addition or removal of display devices,
with the added component. With this change in the configuonly became effective upon a restart, or reboot, of the
ration of the display space, the added component becomes
computer system. As part of its initial startup procedure, the
immediately available for use.
computer's operating system detects the presence of each
By means of this approach, the user can add a second
device driver loaded on the system, and registers each such 45
monitor or other hardware component to a computer and
detected driver to permit communications to be carried out
begin to use the monitor as soon as it has been connected,
between the operating system and the device with which the
without the need to reboot the computer or otherwise
driver is associated. If a new device and corresponding
interrupt its current operating state.
driver are added to the system after this initialization
procedure, the driver is not registered with the operating 50
Further features and advantages of the invention are
system, and therefore communications do not take place
explained in detail hereinafter in the context of specific
until the operating system goes through its initialization
embodiments that are described with reference to the accomprocedure again, e.g. upon the next reboot of the computer.
panying drawings.
Hence, if a user adds a monitor to the computer system, the
BRIEF DESCRIPTION OF THE DRAWINGS
monitor cannot be used to display information generated by 55
the computer until it has been rebooted.
FIG. 1 is a block diagram of an overall display system
U.S. Pat. No. 5,682,529 discloses a system for dynamiarchitecture;
cally accommodating changes in the display configuration of
FIG. 2 illustrates an example of a display environment;
a computer, without the need to restart the computer. In the
FIG. 3 is a block diagram of a display system architecture
system of this patent, changes can be made to the display 60
which includes plural video cards and display devices;
environment for a computer system while it is in a sleep
FIG. 4 is a block diagram illustrating the operation of the
mode, in which the computer's central processing unit is
device manager; and
maintained in a minimal operating state. When the computer
is "awakened" from this sleep mode, the system of the '529
FIG. 5 is a flowchart illustrating the process by which
patent enables the changed configuration to be immediately 65 changes in the configuration of the display environment
become immediately available to the user, in accordance
recognized, and thereafter utilized in the display of inforwith the principles of the invention.
mation generated by the computer.
SYSTEM FOR REAL-TIME ADAPTATION TO
CHANGES IN DISPLAY CONFIGURATION

US 6,282,646 Bl

3
DETAILED DESCRIPTION

4

2. Objects and other information to be displayed can be
positioned anywhere within this space, as determined by the
The present invention is directed to the display environuser and/or the software program that generates the informent of a computer system. A block diagram of the overall
mation. A reference point in this space, e.g. its origin or 0,0
architecture for a display environment is illustrated in FIG. 5 coordinate point, is usually established with reference to
1. In this figure, hardware components of the computer
some object that is always present in the display. For
system are illustrated above a dashed line 10, and software
instance, most graphical user interfaces include some type of
components are depicted below the line. These software
menu bar or other structure which enables the user to access
components are stored in a suitable computer-readable
basic commands to control the computer. The device which
medium, such as a magnetic disk, and loaded into the 10 displays this menu bar is known as the main display device.
computer's working memory, i.e. RAM, for execution. The
If the computer system contains multiple display devices,
system can include display devices 12, e.g. monitors, LCD
only one of the devices is designated as the main device,
screens and/or plasma displays, although actual display
even if multiple devices contain the menu bar. The origin of
the coordinate display space is typically established with
devices need not be physically present in order for the
reference to the menu bar. For example, as illustrated in FIG.
principles of the invention to be operative. Each display
device is connected to, and controlled by, a video card 14 15 2, the 0,0 point 38 in the coordinate space can coincide with
the top left corner of a menu bar 36. The positions of all
which operates in accordance with video driver software 16.
objects and other information to be displayed in the display
Although depicted as being on a separate substrate, such as
space 30 are defined by their coordinates within this space.
a printed circuit board, the components of at least one video
The operating system receives this coordinate information,
card could be incorporated with other components on a
20 for example from the software programs 20 which generate
single substrate, such as the computer's motherboard.
the information, and provides it to the display driver to cause
One or more software programs, such as application
the information to appear at the appropriate place on the
programs 20, generate information to be displayed on the
screen of the display device located at the corresponding
display devices. Examples of such information include text,
position in the display space.
windows and other graphical objects, and control structures 25
In the example illustrated in FIG. 2, the display environsuch as menus and dialog boxes. This information is prement consists of two display devices, 32 and 34, within the
sented to the display device through the computer's operglobal display space 30. A menu bar 36 is displayed at the
ating system 18, which also generates its own information to
top of the screen for the device 32, which is therefore the
be presented on the display. The operating system commumain display device. Accordingly, the origin 38 of the
nicates with the display device through an associated display 30 display space coincides with the top left corner of the device
driver 13, which constitutes a software component that
32. As illustrated in FIG. 2, the user has caused some
corresponds to the hardware of the display device 12.
objects, e.g. windows 40, to be displayed on the device 32,
and another object 42 to be displayed on the device 34.
The operating system includes a display manager 22,
which provides communication between each of the softFIG. 3 illustrates the configuration of the computer sysware components, and dynamically configures the display 35 tem for the particular example illustrated in FIG. 2, which
devices 12. The communication between the various softincludes two display devices. Each display device is connected to an associated video card, which includes a correware components and the hardware devices takes place via
sponding video driver. For the sake of simplicity in FIG. 3,
their associated drivers, e.g. the video driver and the display
the display drivers are not separately illustrated, but are
driver. In this regard, many video displays have the capability to provide information regarding their available modes 40 assumed to be present within the system, in a manner
analogous to the arrangement shown in FIG. 1. The embodiof operation and/or timing specifications. Some displays,
ment of FIG. 3 includes two video cards 14 and 14',
so-called "smart displays," are capable of providing information about their modes of operation directly, for example
respectively associated with the two video display devices
in response to inquiries. For these types of displays, the
12 and 12'. Each of the video cards communicates with the
display manager 22 communicates directly with the display 45 display manager 22, by means of its associated video driver
device, by means of the display driver 13, over a commu16 and 16'.
nication channel 24. This communication channel can be a
Among other components, each video card includes a
bus within the computer, a serial line, or any other suitable
frame buffer, e.g. random access memory, which stores the
path for exchanging information between the display mandata for the image that is displayed on its associated display
ager and the display driver 13 of the display device.
50 device 12. In essence, the display manager 22 assigns the
frame buffer to a corresponding portion of the global coorIn some cases, the display device may not be able to
dinate space 30. In the example of FIG. 2, the two frame
communicate its capabilities directly. However, through the
buffers are assigned to mutually exclusive portions of the
use of a lookup table or the like, the display driver 13 can
obtain information regarding the display's capabilities, and
global space. However, some or all of the portion assigned
55 to one of the frame buffers could overlap with the area
provide them to the display manager.
assigned to the other frame buffer. In this case, the same
The display manager also communicates with other parts
image, or portion of an image, appears on both display
of the operating system 18 and the other software programs
devices.
20 that are running on the computer. For example, in
response to operator commands, the operating system can
At any given time, there could be only one video card
instruct the display manager to add a new device to a list of 60 connected to the computer, or both cards could be connected. Furthermore, in the case of a network server or the
active displays, or remove a device therefrom. In response
thereto, the display manager informs the application prolike, it is possible that no video card would be present over
grams 20 of the new display configurations, to enable them
certain periods of time. Even when both cards are present,
to update their displayed information accordingly.
only one of them may have a monitor or other display device
In one known implementation for computer systems, the 65 connected to it at any particular point in time.
display environment can generally be considered to be
In the case of a conventional desktop or notebook comdefined by a global coordinate space 30, as depicted in FIG.
puter system, one of the video cards might be incorporated

US 6,282,646 Bl
5

6

within the structure of the computer system, and may not be
designed to be repeatedly inserted and removed by the user.
Additional video cards, however, might be capable of being
easily inserted into and removed from the computer system.
For example, the video card might be implemented in a
removable card that conforms to the PC Card standard. This
standard defines the form factor for relatively small, creditcard shaped I/O devices, which are designed to be easily
inserted into and removed from computer housings, to
provide a computer with different capabilities. Included
among the types of I/O devices that can be embodied in such
a card are modems, facsimile devices, network interface
cards, wireless communications devices and hard disk
drives.
Devices of this type which conform to this standard,
commonly known as PC Cards, are designed to be readily
inserted and removed from the computer housing. The
detection of the presence of such devices, as well as their
removal from the system, is handled by a portion of the
computer's operating system that is referred to herein as a
device manager. Referring to FIG. 4, when a PC Card 44 is
inserted into the housing of the computer, it actuates a switch
46, or equivalent sensor device, which sends an interrupt
signal IRQ to the device manager 48. In response to this
interrupt, the device manager determines the type of device
which has been inserted, and informs the operating system
18. In a similar manner, whenever the PC Card is removed
from the computer housing, an interrupt is also sent to the
device manager, which in turn notifies the operating system
that the device is no longer available.
Another type of change which can be made to the display
configuration of the computer is the addition or removal of
a display device. In the example of FIG. 3, for instance,
either one of the display devices 12 or 12' could be disconnected from its associated video card 14 or 14'. Furthermore,
if only one display device is present, it could be disconnected from one of the video cards 14 and connected to the
other video card 14'. Whenever a change of this nature
occurs, an interrupt is sent to the device manager 48. For
instance, the interrupt could be generated by the video card,
upon detecting that a display device has been physically
connected to or disconnected from it. Alternatively, the
interrupt could be provided by a bus that is capable of
detecting such a change.
The addition or removal of other types of hardware can
also result in a change in the display configuration of the
computer system. For example, a graphics accelerator card
can be added to the system by means of a PC Card slot.
Again, upon the addition or removal of such a device, an
interrupt signal IRQ is sent to the device manager.
The present invention is particularly directed to the situation in which the device that is added to or removed from
the computer system is related to the display function. In the
past, it was necessary to reboot the computer system in order
for a change in video hardware to become effective. More
particularly, unless a reboot occurred, the operating system
was not prompted to undertake any action which would
cause it to detect the presence of a new driver, resulting from
the addition of an associated hardware device. Hence, it was
necessary for the user to interrupt the operating state of the
computer in order to utilize the additional functionality
provided by a newly added hardware. Once the operating
system became aware of the presence of the new driver, it
could notify the display manager to incorporate the presence
of the new frame buffer.
In accordance with the present invention, however, the
display system can be immediately responsive to the addi-

tion or removal of video hardware, so that the capabilities of
a revised configuration can be employed without the need to
change the operating state of the computer. This functionality is accomplished by, in effect, bypassing the need to
have the operating system actively determine the addition or
removal of a display device. Rather, the notification of a
change in the configuration of the display environment is
provided directly to the display manager, so that it can
directly account for the presence or absence of a particular
video device.
To this end, whenever a PC Card is added to or removed
from the computer system, the device manager determines
whether the card relates to a display function. A similar
determination is made whenever an interrupt is generated
that indicates some other type of hardware has been added
or removed, e.g. a display monitor. In addition to, or in lieu
of interrupts, other approaches can be employed to determine when a device has been added or removed. For
example, the operating system can periodically poll all of the
computer system's I/O ports, to determine which devices are
present and which ones might have been removed.
Referring to FIG. 5, upon receipt of an indication that
there has been a change in configuration, the device manager
first determines at step 50 whether a device has been added
or removed. If a device has been added to the system, the
device manager communicates with the device to determine
its type, at step 52, and stores data in a register regarding the
identity and type of the device. If the device responds with
an indication that it is a video device, the device manager
issues a call to the display manager 22, at step 54. Appropriate parameters can be included with the call, to indicate
the type of device, the size of its frame buffer (if applicable),
its resolution, and the like.
In response to this information, the display manager
carries out a number of operations, depicted in Steps 56-64.
First, it registers the added hardware as a new device, along
with the location of its associated drivers in memory, at step
56. In some cases, the driver may already be present in
memory, but in an inactive state because the device was not
connected to the system at the time of initial boot. In this
case, the display manager switches the driver to an active
state.
After registering the device, the display manager matches
each display device with an available frame buffer at step 58.
If a new video card is inserted, for example, the display
manager assigns a portion of the global coordinate space 30
to the frame buffer in the video card. If a display device is
connected to that video card, the display manager assigns
that device to the frame buffer for that card, so that the
proper data is displayed on the device. If a display device is
disconnected from one video card and connected to a
different video card, the display manager moves objects
within the global space 30 so that they are presented to the
appropriate frame buffer for the display device. For
example, the display manager can move user interface
control objects which are specific to that display, such as
brightness and contrast controls, to the frame buffer associated with that display. Similarly, if the display has other
attributes associated with it, such as a certain name or
designation, the display manager ensures that they are
directed to the proper frame buffer.
Once the display devices and frame buffers are matched
up, the display manager consults a preferences file which
indicates whether that device was connected to the system at
some previous time. This file is preferably stored in permanent memory, such as a hard disk, and updated each time a

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US 6,282,646 Bl
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video device is added to or removed from the computer
system to change its configuration. The file stores the state
of the display just prior to the change. For instance, it may
store the location of the menu bar and all other objects on the
desktop of the user interface, along with each device that
made up the configuration. It can store relevant operating
parameters for the device as well, such as timing values,
color depth, and the like. When a new device is added, the
display manager determines whether the changed configuration had existed previously, and if so it attempts to restore
the display environment to the state that existed the last time
that configuration was present, at step 60. For example, it
might move the menu bar and certain icons to the screen of
a newly added display device, if they were previously
located on that device before it was disconnected, or set the
timing of an added frame buffer.
In addition to these actions, at step 62 the display manager
can inform currently executing programs of the presence of
the new video device, as described in detail in U.S. Pat. No.
5,682,529, the disclosure of which is incorporated herein by
reference. Furthermore, other software which is not
executing, but which relates to the new device, can be
activated. For instance, if a graphics accelerator card is
inserted in a PC Card slot, the software associated with that
card can be automatically launched.
The display manager also functions at step 64 to rebuild
or reconfigure resources that might be employed by the new
device. For example, in some display modes a table lookup
operation is carried out to determine the colors which are
displayed on the monitor. Different application programs
may utilize different tables for this purpose. Typically, the
window which is in the foreground of a display controls the
particular table that is used. Therefore, when windows are
moved onto a new display device, for instance in accordance
with the preferences file, the display manager rebuilds the
color lookup table stored in the frame buffer for that device
so that it corresponds to the appropriate window.
If the device manager determines at step 50 that a device
has been removed from the system, rather than added, it
determines at step 66 whether the removed hardware was a
video device, for example by reference to previously stored
information which indicated the type of card inserted into
each PC Card slot, or the like. If a determination is made that
the removed device was part of the video subsystem, the
device manager sends a call to the display manager 22, at
step 68, to inform it of this fact. In response thereto, the
display manager updates the preferences file at step 70, to
record the relevant parameters that pertain to the most recent
configuration. In addition, the display manager can attempt
to restore preferences that pertain to the new condition.
Thus, for example, if the computer system had two display
devices and one was removed, the preferences file would be
updated to store the relevant data for the two-monitor
configuration, and then searched to determine whether it
contains data for a one-monitor configuration. The display
manager then rebuilds the display configuration, at step 72.
For example, if the removed device is a video card, the
display manager deletes the assignment of a portion of the
display space to the now-removed frame buffer. In concert
with this action, the display manager can also function to
move objects that were previously displayed on the removed
display device to an area associated with a remaining display
device, as described in greater detail in U.S. Pat. No.
5,682,529. If the removed device had executing software
associated with it, the display manager can cause the software to shut down.
A special case can occur if all frame buffers, e.g. video
cards, are removed from the system. Since the frame buffer

is a memory-mapped I/O device, a program or other device
could attempt to address memory that is no longer present.
Typically, when such a situation occurs, the operating system recognizes it as an error condition, and shuts down the
process which attempted to address the non-existent
memory. However, in the system of the present invention, if
an attempt is made to address memory in a video device, e.g.
a frame buffer, the resulting error condition is treated as an
interrupt. This interrupt is relayed to the display manager to
cause it to reconfigure the display environment, and delete
the assignment of display space to the frame buffer which is
no longer present.
Another action that can occur upon removal of a display
device is to change the operating mode of its display driver.
More particularly, some display devices can operate in one
mode in which adjustment of control buttons, such as
brightness and contrast controls, is accompanied by user
interface feedback, e.g. variation of a sliding scale on the
display. This operating mode requires communication with
the computer's operating system. In another operating mode,
referred to as a remote mode, no such user feedback is
provided. In the system of the present invention, when a
display device is to be removed, the display manager
instructs its display driver to switch to the remote mode, so
that no attempt is made to affect the user interface while the
device is not present.
From the foregoing, it can be seen that the present
invention provides a hot-plugging capability for video
devices, that enables users to immediately take advantage of
changes in the display configuration of a computer system,
such as the addition of a new video card. This functionality
is attained by providing notification of the changed configuration directly to the display manager, rather than waiting for
an action that prompts the operating system to review the
current configuration, such as rebooting the computer.
It will be appreciated by those of ordinary skill in the art
that the present invention can be embodied in other specific
forms without departing from the spirit or essential characteristics thereof. For example, while one embodiment of the
invention has been described in the context of the insertion
and removal of video cards that are embodied in PC Cards,
it will be appreciated that the principles which underlie the
invention are not limited to this particular implementation.
Rather, any other suitable mechanism which accommodates
the addition and removal of a video device can benefit from
the features of the present invention. The presently disclosed
embodiments are therefore considered in all respects to be
illustrative, and not restrictive. The scope of the invention is
indicated by the appended claims, rather than the foregoing
description, and all changes that come within the meaning
and range of equivalents thereof are intended to be embraced
therein.
What is claimed is:
1. A method for reconfiguring a computer system to
accommodate changes in a display environment, comprising
the steps of:
detecting the addition or removal of an input/output
device in the computer system;
determining whether an input/output device which has
been added or removed is a video device, in response
to said detection;
providing a notification to a display manager when a
determination is made that a video device has been
added or removed; and
modifying the allocation of display space to display
devices via said display manager, in accordance with
the addition or removal of a video device.

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2. The method of claim 1 wherein the video device
comprises a video card that includes a frame buffer, and said
modification step includes assigning a portion of the display
space to the frame buffer of an added video card, or deleting
the assignment of a portion of the display space to a removed
video card.
3. The method of claim 1 wherein said display manager
further carries out the step of storing a preferences file that
identifies the status of displayed objects prior to a change in
the configuration of a computer.
4. The method of claim 3 wherein, upon detection of the
addition of a video device, said display manager repositions
objects in said display space, in accordance with a status
stored in said preferences file.
5. The method of claim 1 wherein said video device is a
display device, and said display manager carries out the step
of assigning a respective frame buffer, which corresponds to
an allocated portion of the display space, to a corresponding
display device.
6. The method of claim 1 wherein, upon detection of the
addition of a video device, said display manager causes a
software program associated with the added device to be
launched.
7. The method of claim 1 wherein said display manager
further carries out the step of reconfiguring a computer
resource to correspond to the status of objects located in the
display space.
8. The method of claim 7 wherein said computer resource
is a color look-up table.
9. The method of claim 1, further including the step of
recognizing an error condition resulting from an attempt to
address a frame buffer that has been removed, providing a
notification to said display manager in response to said error
condition, and deleting an allocation of display space to the
removed frame buffer.
10. A system which provides hot-plugging capabilities for
display devices, comprising:
a video device including a frame buffer for storing data
that defines an image to be displayed on an associated
display device;
a display manager which defines a display space and
assigns a portion of said display space to said frame
buffer, and which provides data for images to be
displayed to said frame buffer; and
a device manager which detects the addition or removal of
a device in a computer system, determines whether a
device which has been added or removed is a video
device, and provides a notification of such addition or
removal to the display manager when a video device is
determined to have been added or removed, to cause
the assignment of a portion of the display space to be
modified in accordance with a detected addition or
removal.
11. The system of claim 10, wherein said display manager
launches a software program associated with the video
device in response to notification that the video device has
been added.
12. The system of claim 11 further including a preference
file stored in memory which indicates the status of objects
being displayed when a video device is removed.
13. A system which provides hot-plugging capabilities for
display devices, comprising:
at least one display for displaying images;
a display manager which defines a display space and
assigns a portion of said display space to a display
device, and which provides data for images to be
displayed on said display device; and

a device manager which detects the addition or removal of
a device in a computer system, determines whether a
device which has been added or removed is a display
device, and provides a notification of such addition or
removal to the display manager when a display device
is determined to have been added or removed, to cause
the assignment of a portion of the display space to be
modified in accordance with a detected addition or
removal.
14. The system of claim 13 further including a frame
buffer which is associated with an assigned portion of the
display space, and wherein said display manager modifies
said assignment by associating said frame buffer with said
display device.
15. The system of claim 13 further including a preference
file stored in memory which indicates the status of objects
being displayed when a display device is removed.
16. A computer-readable medium containing a device
manager program and a display manager program, wherein
said device manager program performs the steps of
detecting the addition or removal of an input/output
device in a computer system,
determining whether the input/output device is a video
device, and
providing a notification to the display manager program
when a video device is added or removed;
and wherein said display manager performs the step of:
modifying the allocation of display space to display
devices in response to said notification from the
device manager.
17. The computer-readable medium of claim 16, wherein
said display manager further performs the steps of storing a
preference file relating to the status of objects appearing on
a display device, and restoring objects to the status stored in
the preferences file when a video device is added.
18. The computer-readable medium of claim 16, wherein
said display manager performs the step of assigning a
respective frame buffer to a display device in response to
said notification of an added display device, or deleting the
assignment of a respective frame buffer from said display
device in response to said notification of a removed display
device.
19. The computer-readable medium of claim 16, wherein
said display manager performs the further step of launching
a software program in response to said notification.
20. The computer-readable medium of claim 16, wherein
said display manager performs the further step of reconfiguring at least one computer resource in accordance with the
modification of the display space allocation.
21. The computer-readable medium of claim 20, wherein
said computer resource is a color look-up table.
22. The method of claim 3, wherein said preference file
stores the video devices which make up the configuration of
the computer, and the locations of objects displayed on said
video devices.
23. The method of claim 22, wherein said preferences file
also stores operating parameters for said devices.
24. A method for reconfiguring a computer system to
accommodate changes in a display environment, comprising
the steps of:
detecting the addition or removal of a video device in the
computer system;
providing a notification to a display manager that a video
device has been added or removed;
modifying the allocation of display space to display
devices via said display manager, in accordance with
the addition or removal of a video device; and

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providing a notification to the display manager program
reconfiguring a color look-up table to correspond to the
status of objects located in the display space.
when a video device is added or removed;
25. A system which provides hot-plugging capabilities for
and wherein said display manager performs the steps of:
display devices, comprising:
modifying the allocation of display space to display
a video device including a frame buffer for storing data 5
devices in response to said notification from the
that defines an image to be displayed on an associated
device manager, and
display device;
storing a preference file relating to the status of objects
a display manager which defines a display space and
appearing on a display device, and restoring objects
assigns a portion of said display space to said frame
to the status stored in the preferences file when a
buffer, and which provides data for images to be 10
video device is added.
displayed to said frame buffer;
30. The computer-readable medium of claim 29, wherein
a device manager which detects the addition or removal of
said preference file stores the video devices which make up
the video device to a computer system, and provides a
the configuration of the computer, and the locations of
notification of such addition or removal to the display 15 objects displayed on said video devices.
manager to cause the assignment of a portion of the
31. The computer-readable medium of claim 30, wherein
display space to be modified in accordance with a
said preferences file also stores operating parameters for said
detected addition or removal; and
devices.
means responsive to the removal of a video device for
32. A computer-readable medium containing a device
storing a preference file in memory which indicates the 20 manager program and a display manager program, wherein
status of objects being displayed.
said device manager program performs the steps of:
26. The system of claim 25, wherein said display manager
detecting the addition or removal of a video device in a
is responsive to the addition or removal of a video device to
computer system, and
restore displayed objects to a status stored in said preference
providing a notification to the display manager program
file which corresponds to the configuration of the computer 25
when a video device is added or removed;
system after the video device is added or removed.
27. The system of claim 25, wherein said preference file
and wherein said display manager performs the step of:
stores the video devices which make up the configuration of
modifying the allocation of display space to display
the computer, and the locations of objects displayed on said
devices in response to said notification from the
video devices.
30
device manager, and
28. The system of claim 27, wherein said preferences file
reconfiguring at least one computer resource in accoralso stores operating parameters for said devices.
dance with the modification of the display space
29. A computer-readable medium containing a device
allocation.
manager program and a display manager program, wherein
33. The computer-readable medium of claim 32, wherein
said device manager program performs the steps of:
35 said computer resource is a color look-up table.
detecting the addition or removal of a video device in a
computer system, and
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