Changing hardware abstraction layer in Windows 2000 / XP

Windows NT is able to use different Hardware Abstraction Layers (HAL). Two of them is Standard PC and ACPI PC, which has different ways of performing hardware resource management:
    • Completely PnP and handles the configuration of your devices(PnP) and gives you no control. It can solve most resource conflicts. If a conflict happens then it has be fixed in BIOS or changing addon cards.
    • Includes power management, so if having a laptop it will help on battery time
    • Doesn't show the actual hardware IRQ's the different devices uses, instead it has one of these behaviors:
      • It looks like all devices are sharing the same IRQ, but it just means they are controlled by the same ACPI Controller
      • It looks like all devices have their own IRQ, but assigned IRQ is an software IRQ (>15)
  • Standard PC
    • Includes some Plug'n'Play (PnP) but still allow you to configure your devices. There is a higher chance of resource conflict, but you might be able to solve it in Windows before going into BIOS.
    • Limited power management features, and for some motherboards it gives better performance and less conflicts
    • Will show the actual hardware IRQ's the different devices are using
It is possible to change from ACPI to Standard PC after having installed Windows, though some reports problems doing this. It is recommended to make a backup of your current "Hardware Profile" before applying this:
  1. Go to "System Properties" in Control Panel
  2. Select the tab "Hardware" (Press the button "Hardware Profiles" to make a backup before continuing)
  3. Press the button "Device Manager" (Will bring forth a tree)
  4. Find the node "Computer" and expand
  5. You should now see a component called "Advanced Configuration and Power Interface (ACPI) PC"
  6. View component properties (Double click the component)
  7. Select the tab "Driver"
  8. Press the button "Update Driver..."
  9. Select the option "Display list of the known drivers..."
  10. It will now show the current driver for the component
  11. Select the option "Show all hardware of this device class"
  12. It will now show different types of computers
  13. Select the driver "Standard PC"
  14. It will now redetect all your hardware
Note one can also use the change of Computer Driver, when upgrading to a dual processor thus having multiple CPUs (Or just enabling Intel HyperThreading (HT)). More Info MS KB234558.

Note it is possible to specify what HAL Windows should use during the install, instead changing HAL after the install, and is most likely the best way:
  • One way is to edit the file "C:\Txtsetup.sif"(It is made during the textual part of the install process) by setting:

    ACPIEnable = 0 (Disabled = 0, Enabled if ACPI BIOS = 1, Enabled if certified ACPI BIOS = 2, Default = 2)

  • Another way is to Press F7 when Win2k install says "Press F6 if you need to install a third party SCSI or RAID driver". It will not give any confirmation of that you pressed F7, but it will not use ACPI.
  • Yet another way is to press F5 instead of F7. This will bring forth a menu where it is possible to select from a whole range (Might have to press arrow-up/down to see them all):
    Standard PCHal.dllAny Standard PC, non-ACPI and non-MPS (Usually 386, 486, Pentium, Pentium II, or Pentium III)
    ACPI PCHalacpi.dllApplies to a single processor motherboard with single processor (Pentium 4, Athlon)
    ACPI Multiprocessor PCHalmacpi.dllApplies to a multiple-processor ACPI computer.
    ACPI Uniprocessor PCHalaacpi.dllApplies to an ACPI multiple-processor board but with a single processor installed.
    MPS MultiprocessorHalmps.dllApplies to non-ACPI computers with a dual processor running.
    MPS UniprocessorHalapic.dllApplies to non-ACPI computers dual processor motherboard with a single processor installed.
More Info MS KB216251
More Info MS KB216573
More Info MS KB224826
More Info MS KB234558
More Info MS KB237556
More Info MS KB243883
More Info MS KB252420
More Info MS KB295116
More Info MS KB299340
More Info MS KB309283


  1. Lov3ofgod says:

    Din't think would need to learn all these.....but have to now since my comp crashed....and my fcking vendor says cng the MB. Think this knowledge ,ll be essential if I were to solve the problem by myself.

  2. raghavs ood says:

    hey i am using the hp pavilion dv6 6145tx laptop computer system and when i try to install windows xp 32 bit and 64 - bit i cant install it.
    I am using, floppy drive and i also pick the F7 option. It doesnt seem to help. During f6 option is press f7 repeadedly but nothing comes up. At the end THE BLUE SCREEN OF DEATH COMES saying that ACPI.SYS (ADVANCED CONFIGURATION POWER INTERFACE ERROR. I pressed F7 again. So why am i getting this error. I have loaded my intel SATA mobile express chipset family driver as well via pressig the F6 key with no F7 key but that does the same thing.

    - I have also tried and integrating the drivers like i did for the floppy drive on the windows xp cd itself. Try booting that with ACPI off/F7 or with ACPI.sys there however, the BLUE SCREEN OF DEATH KEEPS COMMING,

    In my BIOS, which is latest updated. The IDE/Achi Option is not present. The boot from floppy and PXE boot option is there.

    - I have tried installing Xp on another laptop computer which has the option to select between IDE AND ACHI TYPE DRIVES IN IT'S BIOS OPTIONS. This laptop was configured WITH ide option therefore, the installation of xd was successfull. Then i took that hard drive out of my laptop and put it inside this computer i am having trouble with . As soon as i did that the WINDOWS XP loading screen appears and then the system just shuts down.

    So people who are having trouble, if they have old pc with tHE IDE OPTION IN THEIR BIOS, THEN PLZ TRY AND INSTALL xp on old pc on that hard drive, then take it out and then put it into the new pc you are having problems with. So since xp hdd is there it should boot up..

    please somone mail me solution?

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