Ulllted States Patent [19]
`Hobson et al.
`
`US006115813A
`[11] Patent Number:
`[45] Date of Patent:
`
`6,115,813
`Sep. 5, 2000
`
`[54] SELECTIVELY ENABLING ADVANCED
`CONFIGURATION AND POWER
`INTERFACE BIOS SUPPORT
`
`5,903,894
`
`5/1999 Reneris ................................. .. 707/100
`
`OTHER PUBLICATIONS
`
`[75] Inventors: Louis B. Hobson, Tomball; Christine
`G_ Cash, Cypress, both of Tex
`
`Intel/Microso?/Toshiba, “Advanced Con?guration and
`Power Interface Speci?cation”, Revision 1.0, Dec. 22, 1996.
`
`[73] Assignee: Compaq Computer Corporation,
`Houston, TeX.
`
`[21] Appl. No.: 09/035,166
`
`Mar‘ 5’ 1998
`[22] Flled:
`[51]
`Int. Cl.7 ...................................................... .. G06F 9/44
`[52] US. Cl. ................................................................. .. 713/1
`[58] Field of Search .................................. .. 713/1, 2, 300,
`713/320, 323, 324
`
`[56]
`
`References Cited
`
`U.S. PATENT DOCUMENTS
`
`Primary Examiner—Thomas M. Heckler
`Attorney, Agent, or Firm—Conley, Rose & Tayon, P.C.;
`Michael F. Heim; Jonathan M. Harris
`[57]
`ABSTRACT
`
`A computer system is selectively booted into an advanced
`con?guration and poWer interface (ACPI) mode or a non
`ACPI mode during Computer system Start-11p, depending
`upon the Status of a user Speci?ed ?ag The instructions and
`data needed to boot the computer system into ACPI mode
`can be stored in a memory in a format not visible to the
`computer system operating system. A user can specify the
`desired boot mode through a user set-up routine.
`
`5,560,023
`
`9/1996 Crump et a1. ......................... .. 713/323
`
`46 Claims, 4 Drawing Sheets
`
`1
`
`START
`
`I
`
`v
`STANDARD BIOS OPERATIONS 400
`
`MEMORY VERIFICATION J
`HARDWARE HEALTH CHECKS
`DEVICE CONFIGURATION
`
`y
`
`402
`
`READ ACPI ENABLE FLAG J
`
`404
`
`ACPI
`ENABLED?
`
`406
`LOAD ACPI INSTRUCTIONS! _/
`DATA
`
`"
`408
`SET ACPI SIGNATURE J
`
`410
`LOAD AND TRANSFER J
`> CONTROL TO OPERATING
`SYSTEM
`
`V
`
`END
`
`1
`
`

`

`U.S. Patent
`
`Sep. 5, 2000
`
`Sheet 1 of4
`
`6,115,813
`
`
`
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`2
`
`

`

`U.S. Patent
`
`Sep. 5, 2000
`
`Sheet 2 of4
`
`6,115,813
`
`BIOS INSTRUCTIONS
`m
`
`112
`;
`
`ACPI INSTRUCTIONS/DATA
`2-0-2
`
`FIG. 2
`
`?g
`
`ACPI ENABLE FLAG
`
`g 114
`
`FIG. 3
`
`104
`
`112
`
`ACPI
`INSTRUCTIONS/
`DATA
`ZQZ
`
`ACPI OPAQUE
`LOCATION
`502
`---
`
`ACPI KNOWN
`LOCATION
`5%
`
`Q9
`
`504
`
`FIG. 5
`
`3
`
`

`

`U.S. Patent
`
`Sep. 5, 2000
`
`Sheet 3 0f 4
`
`6,115,813
`
`STANDARD BIOS OPERATIONS
`
`400
`
`MEMORY VERIFICATION
`HARDWARE HEALTH CHECKS
`DEVICE CONFIGURATION
`
`I
`
`READ ACPI ENABLE FLAG
`
`404
`
`ACPI
`ENABLED?
`
`LOAD ACPI INSTRUCTIONS/
`DATA
`
`I
`
`SET ACPI SIGNATURE
`
`I
`
`LOAD AND TRANSFER
`CONTROL TO OPERATING
`SYSTEM
`
`402
`
`406
`
`408
`
`410
`
`FIG. 4
`
`4
`
`

`

`U.S. Patent
`
`Sep. 5, 2000
`
`Sheet 4 0f 4
`
`6,115,813
`
`>
`
`600
`BEGIN SYSTEM J
`START-UP
`I,
`ENTER SETUP
`ROUTINE
`604
`I
`SELECT ACPI J
`ENABLE FLAG
`
`602
`__/
`
`YES
`
`FLAG
`MODIFIED?
`
`606
`
`610
`
`STORE MODIFIED
`ACPI ENABLE FLAG
`VALUE
`
`608
`CONTINUE START—UP J
`
`FIG. 6
`
`5
`
`

`

`1
`SELECTIVELY ENABLING ADVANCED
`CONFIGURATION AND POWER
`INTERFACE BIOS SUPPORT
`
`BACKGROUND
`
`The invention relates to selectively enabling Whether a
`computer system boots-up into an advanced con?guration
`and poWer interface (ACPI) mode or a non-ACPI mode.
`KnoWn poWer management and con?guration techniques,
`such as the advanced poWer management (APM) and the
`plug-and-play speci?cations, Were implemented by basic
`input-output system (BIOS) instructions stored in read-only
`memory. When a poWer management or con?guration event
`occurred (e.g., a request to transition from an “on” state to
`a “sleep” state), the BIOS received notice of the event via an
`operating system transparent interrupt knoWn as a system
`management interrupt. It Was the responsibility of the BIOS
`to manipulate the necessary softWare state information and
`to control the system’s hardWare and perform the requested
`action.
`Under the neW ACPI, When a poWer management or
`con?guration event occurs the operating system is noti?ed
`via an operating system visible interrupt knoWn as a system
`control interrupt (SCI). It is the operating system itself that
`directs all system and device poWer state transitions. Central
`to ACPI operations is an ACPI driver. This driver is an
`operating system level program Which receives notice of all
`SCI events and either performs the necessary event handling
`actions itself, or passes control to an ACPI control method.
`The ACPI speci?cation represents an abstract interface
`betWeen a computer system’s hardWare and ?rmWare and its
`operating system. The ACPI includes hardware registers,
`tables, and BIOS. ACPI registers are used to store and pass
`event information betWeen the hardWare/?rmWare and oper
`ating system. ACPI tables are used to describe system
`information (e.g., supported poWer states, poWer sources,
`clock sources), features (e.g., available hardWare devices),
`and methods for controlling those features (e.g., ACPI
`control methods). ACPI BIOS is that part of the computer
`system ?rmWare that implements the ACPI speci?ed inter
`faces for sleep, Wake, some restart operations, and provides
`permanent storage of ACPI table information.
`An ACPI operating system detects an ACPI compliant
`BIOS by searching predetermined BIOS memory addresses
`for a speci?ed byte pattern, also knoWn as a signature. Upon
`?nding this pattern, the ACPI operating system commands
`the BIOS into ACPI mode. If the speci?ed byte pattern is not
`found, the operating system Will perform poWer manage
`ment and device con?guration services according to legacy
`(e.g., APM) speci?cations.
`
`SUMMARY
`
`In one aspect, the invention features a computer system
`having a host processor, random access memory, basic
`input-output system (BIOS) memory, a detector, and a mode
`circuit. The detector is con?gured to detect if the user
`speci?ed an advanced con?guration and poWer interface
`(ACPI) start-up or a non-ACPI start-up. The mode circuit is
`connected to the detector and, if the user speci?ed an ACPI
`start-up, loads ACPI instructions from the BIOS memory to
`the random access memory at a location knoWn by the ACPI
`operating system.
`In some embodiments, the ACPI instructions are stored in
`a compressed format in the BIOS memory. The BIOS
`memory may, or may not, also include non-ACPI start-up
`
`6,115,813
`
`2
`instructions. BIOS memory may be a read-only random
`access memory. The computer system can include additional
`elements such as: a non-volatile memory Which can be used
`to store the user speci?ed mode; and an input-output device
`such as a mass storage device, a keyboard, or a pointer.
`In another aspect, the invention provides a method to
`start-up a computer system. The method determines Which
`mode a user speci?ed and, if the speci?ed mode is ACPI,
`loads ACPI instructions into system memory. If the user
`speci?ed a non-ACPI mode, non-ACPI start-up instructions
`are loaded into system memory.
`
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`BRIEF DESCRIPTION OF THE DRAWINGS
`
`FIG. 1 shoWs a computer system.
`FIG. 2 shoWs a read-only memory device.
`FIG. 3 shoWs a non-volatile random access memory
`(NVRAM) device.
`FIG. 4 shoWs computer system start-up operations.
`FIG. 5 shoWs loading advanced con?guration and poWer
`interface instructions and data from read only memory to
`random access memory during computer system start-up.
`FIG. 6 shoWs a method to modify a status ?ag in non
`volatile random access memory.
`
`DETAILED DESCRIPTION
`
`Referring to FIG. 1, computer system 100 (alloWing a
`user to select Whether to boot into an advanced con?guration
`and poWer interface (ACPI) mode or a non-ACPI mode)
`includes host processor (CPU) 102 and random access
`memory (RAM) 104 coupled to system bus 106. Illustrative
`host processors 102 include the PENTIUM, PENTIUM
`PRO, PENTIUM-II, and 80x86 families of processors from
`Intel Corporation.
`Bridge circuit 108 couples system bus 106 to secondary
`bus 110. Components coupled to secondary bus 110 include:
`read only memory (ROM) 112; nonvolatile RAM
`(NVRAM) 114; input-output (I/ O) control circuit 116; video
`controller 118 and associated display 120; disk controller
`122 and associated disks (one shoWn) 124; and one or more
`expansion slots 126. Input-output circuit 116 couples com
`ponents such as keyboard 128, pointer device 130, and serial
`132 and parallel 134 ports to computer system 100. System
`ROM 112 and NVRAM 114 are described in more detail
`beloW.
`As shoWn in FIG. 2, system ROM 112 includes BIOS
`instructions 200 and ACPI instructions/data 202. ACPI
`instructions/data 202 include, for example, ACPI table data
`and static poWer management information. As shoWn in
`FIG. 3, NVRAM 114 includes ACPI enable ?ag 300 Which
`is used during computer system start-up to determine if
`ACPI instructions/data 204 should be loaded into system
`RAM 104 for subsequent use by an ACPI operating system.
`Referring noW to FIG. 4, When computer system 100 is
`poWered up or reset, host processor 102 begins executing
`BIOS start-up instructions from system ROM 112. After
`performing standard BIOS actions such as verifying system
`memory, performing hardWare health checks, and con?gur
`ing system devices (step 400), a check is made to determine
`if computer system 100 should boot-up in an ACPI aWare
`mode. Speci?cally, BIOS interrogates NVRAM 114 for the
`status of ACPI enable ?ag 300 (step 402). If ACPI enable
`?ag 300 indicates computer system 100 should boot in an
`ACPI aWare mode (the ‘yes’ prong of step 404), ACPI
`instructions/data 202 are loaded into system RAM 104 (step
`406), for use by the ACPI operating system (see step 410),
`
`6
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`6,115,813
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`and the ACPI byte pattern (signature) is established in
`memory space (step 408) as required by the ACPI speci?
`cation. Following step 408, or if ACPI enable ?ag 300
`indicates computer system 100 should be booted into legacy
`mode (the ‘no’ prong of step 404), BIOS looks for and
`transfers control to an operating system (step 410). This last
`step is knoWn as “boot-strapping” the operating system.
`As shoWn in FIG. 5, ACPI instructions/data 202 are
`commonly copied 500 into a ?rst location 502 in system
`RAM 104 during computer system start-up (e.g., during step
`400). While an ACPI operating system may physically
`access this ?rst location 502, information about What data is
`stored there is not generally knoWn (is opaque) to the
`operating system. Thus, ACPI instructions/data 202 initially
`copied into system RAM 104 from system ROM 112 are not
`functionally accessible to the operating system. If ACPI is
`enabled (the ‘yes’ prong of step 404 in FIG. 4), ACPI
`instructions/data are copied 504 from the ?rst location 502
`into a second location 506 that the ACPI operating system is
`cogniZant of during step 406. At this point ACPI
`instructions/data 202 have been loaded.
`ACPI instructions/data 202 can be stored in system ROM
`112 in a compressed format so that the operating system
`cannot determine, by inspecting system ROM 112 directly,
`if ACPI instructions/data are present. This technique saves
`system ROM 212 memory space and, in effect, hides ACPI
`capability from the operating system.
`As shoWn in FIG. 6, the user may selectively set ACPI
`enable ?ag 300 through a user interface. As computer system
`start-up begins (step 600), the user is given an opportunity
`to enter a system set-up routine (step 602) via a predeter
`mined key command (e.g., F10 keystroke). Once in this
`routine, the user can select ACPI enable ?ag 300 for
`modi?cation (step 606). If the user decides against changing
`the status of ACPI enable ?ag 300 (the ‘no’ prong of step
`608), start-up processing continues at step 608 (see FIG. 4).
`If the user modi?es ACPI enable ?ag 300 (the ‘yes’ prong of
`step 606), that change is Written back to NVRAM 114 (step
`610) and computer start-up operations are initiated from the
`beginning at step 600 (see FIG. 4).
`The foregoing description is illustrative only and is not to
`be considered limiting. Various changes in the materials,
`components, circuit elements, as Well as in the details of the
`illustrated operational methods are possible Without depart
`ing from the scope of the claims. For example, system bus
`106 and secondary bus 110 can be proprietary or special
`purpose buses, peripheral component interface (PCI) buses,
`industry standard architecture (ISA) buses, extended indus
`try standard architecture (EISA) buses, or combinations of
`one or more of these buses. ACPI instructions/data 202 can
`be stored in compressed or uncompressed form.
`Additionally, ACPI enable ?ag 300 does not have to be
`stored in NVRAM 114. Any nonvolatile means of storage in
`any location accessible to host processor 102 during start-up
`may be used. Steps of the invention may be performed by a
`computer processor executing instructions organiZed into a
`program module. Storage devices suitable for tangibly
`embodying computer program instructions include all forms
`of nonvolatile memory including, but not limited to: semi
`conductor memory devices such as EPROM, EEPROM, and
`?ash devices; magnetic disks (?xed, ?oppy, and removable);
`other magnetic media such as tape; and optical media such
`as CD-ROM disks.
`Each embodiment of the invention may provide one or
`more advantages. For example, the invention alloWs a user
`to specify Which mode their computer system should start
`up in: ACPI mode, or non-ACPI mode.
`
`4
`
`What is claimed is:
`1. A computer system comprising:
`a bus;
`a host processor operatively coupled to the bus;
`memory operatively coupled to the bus;
`an input-output device operatively coupled to the bus;
`a user speci?ed Advanced Con?guration and PoWer Inter
`face (ACPI) mode indicator operatively coupled to the
`bus; and
`a mode circuit that selectively loads advanced con?gura
`tion and poWer interface instructions into the memory
`depending on the ACPI-mode indicator.
`2. The computer system of claim 1, Wherein the advanced
`con?guration and poWer interface instructions are stored in
`a basic input-output system memory.
`3. The computer system of claim 2, Wherein the basic
`input-output memory comprises a programmable read only
`memory.
`4. The computer system of claim 1, Wherein the advanced
`con?guration and poWer interface instructions include
`advanced con?guration and poWer interface data tables and
`advanced con?guration and poWer interface control method
`instructions.
`5. The computer system of claim 1, Wherein the advanced
`con?guration and poWer interface instructions are, before
`loading, in a compressed form.
`6. The computer system of claim 5, Wherein the com
`pressed advanced con?guration and poWer interface instruc
`tions are not visible, before loading, to an operating system.
`7. The computer system of claim 1, further comprising a
`non-volatile memory operatively connected to the bus.
`8. The computer system of claim 7, Wherein the user
`speci?ed ACPI-mode indicator is stored in the nonvolatile
`memory.
`9. The computer system of claim 1, Wherein the user
`speci?ed ACPI-mode indicator is set by a set-up routine
`having instructions to:
`receive a desired value for the ACPI-mode indicator from
`a user; and
`store the received value in a second memory accessible to
`the host processor.
`10. The computer system of claim 9, Wherein the second
`memory comprises a nonvolatile memory.
`11. The computer system of claim 1, Wherein the input
`output device comprises a pointer device.
`12. A computer system comprising:
`a bus;
`a host processor operatively coupled to the bus;
`an input-output device operatively coupled to the bus;
`random access memory operatively coupled to the bus;
`a basic input-output system memory operatively coupled
`to the bus, the basic input-output system memory
`comprising compressed advanced con?guration and
`poWer interface instructions;
`a nonvolatile memory operatively coupled to the bus, the
`nonvolatile memory comprising a user speci?ed mode
`indicator; and
`a mode circuit that loads the compressed advanced con
`?guration and poWer interface instructions into the
`random access memory depending on the value of the
`user speci?ed mode indicator.
`13. The computer system of claim 12, Wherein the
`advanced con?guration and poWer interface instructions
`comprise advanced con?guration and poWer interface data
`
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`tables and advanced con?guration and power interface con
`trol method instructions.
`14. A computer memory, comprising:
`means for operatively connecting the computer memory
`to a computer bus;
`instructions to determine if a user speci?ed ?ag is set;
`compressed advanced con?guration and poWer interface
`instructions (ACPI) Which run the computer in ACPI
`mode based on the state of the user speci?ed ?ag; and
`non-compressed non-advanced con?guration and poWer
`interface instructions Which run the computer in a
`non-ACPI mode based on the state of the user speci?ed
`?ag.
`15. The computer memory of claim 14, Wherein the
`memory comprises a read-only random access memory.
`16. The computer memory of claim 14, Wherein the
`noncompressed non-advanced con?guration and poWer
`interface instructions comprise instructions to boot a com
`puter system.
`17. A method of starting a computer system that execute
`an advanced con?guration and poWer interface operating
`system, the method comprising:
`determining if a user speci?ed ?ag is set; and
`loading advanced con?guration and poWer interface
`instructions from a ?rst memory to a second memory if
`the user speci?ed ?ag is set.
`18. The method of claim 17, Wherein determining if a user
`speci?ed ?ag is set comprises interrogating a third memory
`for a value of the user speci?ed ?ag.
`19. The method of claim 18, Wherein the third memory is
`a nonvolatile memory.
`20. The method of claim 17, Wherein loading advanced
`con?guration and poWer interface instructions comprises:
`copying advanced con?guration and poWer interface
`instructions from the ?rst memory to a ?rst location in
`the second memory, Where the ?rst location is opaque
`to the operating system; and
`copying the advanced con?guration and poWer interface
`instructions from the ?rst location in the second
`memory to a second location in the second memory
`Where the second location is knoWn to the operating
`system.
`21. The method of claim 17, Wherein the advanced
`con?guration and poWer interface instructions includes
`advanced con?guration and poWer interface data.
`22. The method of claim 17, Wherein non-advanced
`con?guration and poWer interface instructions are loaded
`into the second memory from a fourth memory if the user
`speci?ed ?ag is not set.
`23. The method of claim 17, Wherein the ?rst memory
`comprise a read-only memory including basic input-output
`system instructions.
`24. The method of claim 17, Wherein the second memory
`comprise random access memory.
`25. The method of claim 18, Wherein the ?rst and third
`memory are the same memory.
`26. The method of claim 17, Wherein the advanced
`con?guration and poWer interface instructions comprise
`advanced con?guration and poWer interface data tables and
`advanced con?guration and poWer interface control method
`instructions.
`27. The method of claim 17, Wherein the advanced
`con?guration and poWer interface instructions are in a
`compressed form.
`28. The method of claim 27, Wherein the compressed
`advanced con?guration and poWer interface instructions are
`not visible to an operating system When reading the ?rst
`memory.
`
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`29. A method of starting a computer system for executing
`an advanced con?guration and poWer interface operating
`system, the method comprising:
`determining if a user speci?ed ?ag is set, the user speci
`?ed ?ag being stored in a nonvolatile memory;
`if the user speci?ed ?ag is set, the user speci?ed ?ag being
`stored in a nonvolatile memory;
`if the user speci?ed ?ag is set, decompressing advanced
`con?guration and poWer interface instructions from a
`basic input-output system memory and loading the
`decompressed advanced con?guration and poWer inter
`face instructions into a random access memory; and
`if the user speci?ed ?ag is not set, loading non-advanced
`con?guration and poWer interface instructions from the
`basic input-output system memory into the random
`access memory.
`30. The method of claim 29, Wherein the advanced
`con?guration and poWer interface instructions comprise
`advanced con?guration and poWer interface data tables and
`20 advanced con?guration and poWer interface control method
`instructions.
`31. A computer system, comprising:
`a CPU;
`a video controller coupled to video display device;
`a ?rst system memory containing advanced con?guration
`and poWer interface (ACPI) instructions;
`an ACPI enable ?ag register in a non-volatile random
`access memory for indicating Whether the computer
`system should be run in an ACPI mode;
`a basic input output system (BIOS) program residing on
`said ?rst system memory executed by the CPU that
`reads a status of the ACPI enable ?ag and starting the
`computer system in ACPI mode based on a state of the
`ACPI enable ?ag.
`32. The computer system as de?ned in claim 31 further
`comprising:
`a second system memory coupled to the CPU;
`said BIOS program containing instructions for the CPU to
`execute that copies the ACPI instructions from said ?rst
`system memory to a ?rst location Within the second
`system memory;
`said BIOS program also containing instructions for the
`CPU to execute to copy said ACPI instructions from
`said ?rst location to a second location Within the second
`system memory and establishing an ACPI signature
`byte pattern as required to operate in an ACPI mode
`When the ACPI enable ?ag is asserted.
`33. The computer system as de?ned in claim 32 Wherein
`said ?rst location Within the second memory is not acces
`sible to an operating system residing on the computer system
`and said second location Within second memory is acces
`sible to the operating system.
`34. The computer system as de?ned in claim 31 Wherein
`said ?rst system memory is a read only memory (ROM)
`device.
`35. The computer system as de?ned in claim 32 Wherein
`said second system memory is a random access memory
`(RAM) device.
`36. The computer system as de?ned in claim 31 Wherein
`said ACPI instructions are stored on said ?rst system
`memory in a compressed form.
`37. The computer system as de?ned in claim 36 further
`comprising:
`a second system memory coupled to the CPU; and
`said BIOS program including instructions executed by the
`CPU that Write a decompressed set of ACPI instruc
`
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`6,115,813
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`tions from said ?rst system memory to the second
`system memory including establishing an ACPI signa
`ture byte pattern as required to operate in an ACPI
`mode When the ACPI enable ?ag is asserted.
`38. A computer system read only memory (ROM) device
`comprising:
`advanced con?guration and poWer interface (ACPI)
`instructions; and
`a basic input output system (BIOS) program to read a
`status of an ACPI enable ?ag and starting the computer
`system in ACPI mode based on the ACPI enable ?ag.
`39. The ROM device as de?ned in claim 38 further
`comprising:
`non-ACPI instructions;
`said BIOS program that makes the ACPI instructions
`available to an operating system based on a ?rst state of
`the ACPI enable ?ag; and
`said BIOS program for making the non-ACPI instructions
`available to the operating system based on a second
`state of the ACPI enable ?ag.
`40. The ROM device as de?ned in claim 39 Wherein said
`ACPI instructions are in a compressed format.
`41. Amethod of operating a computer system, the method
`comprising:
`masking an advanced con?guration and poWer interface
`(ACPI) signature byte pattern in a system memory to
`hide the presence of ACPI data and instructions; and
`selectively un-masking said ACPI byte pattern to alloW
`the computer system to run in an ACPI mode.
`
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`42. The method as de?ned in claim 41 Wherein the step of
`masking the ACPI signature byte pattern further comprises
`compressing said byte pattern to create a compressed ACPI
`byte pattern and storing the compressed ACPI pattern in a
`read only memory.
`43. The method as de?ned in claim 41 Wherein the step of
`masking the ACPI signature byte pattern further comprises
`Writing said byte pattern to a location Within a random
`access memory that is not accessible to an operating system.
`44. The method as de?ned in claim 41 Wherein said step
`of selectively un-masking said ACPI byte pattern further
`comprises:
`determining Whether a user speci?ed ?ag is set to indicate
`that the computer should be run in ACPI mode; and
`selectively un-masking the ACPI signature byte based on
`a state of the user speci?ed ?ag.
`45. The method as de?ned in claim 44 Wherein the step of
`un-masking the ACPI signature byte further comprises:
`decompressing the compressed ACPI byte pattern; and
`loading a decompressed ACPI byte pattern into a random
`access memory.
`46. The method as de?ned in claim 44 Wherein the step of
`un-masking the ACPI signature byte further comprises Writ
`ing said byte pattern to a location Within a random access
`memory that is accessible to an operating system.
`
`*
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`*
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`*
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`*
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`*
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`9
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`