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ZXnet http server: Note N00002: Software Power Off on Windows NT 4.0


Note Archive
Number: N00002
Created: 06 September 2007
Revised: 30 September 2007

Windows NT 4.0 does not support software power off out of the box except in some cases of laptop computers. This document provides information on how to enable support.

How it works

The power off operation needs the NT4 kernel to have direct access to the Advanced Power Management hardware on the motherboard. The default Hardware Abstraction Layer (HAL) does not support interaction with the APM hardware and prevents any direct hardware access by the kernel. A company called Softex produced a modified HAL (hal.dll) that adds the required hardware support.

9 steps to win

  1. Obtain a copy of hal.dll from Softex that works with your motherboard hardware. There are two versions available: single processor and multiprocessor. Both versions are included with all service packs from 4 upwards. Tou can extract them from SP6a by using the /x switch from the command prompt. Eg:
    D:\Q246009i.exe /x"
  2. After the integrity of the archive is verified, a dialog box will appear asking where you want to store the contents of the service pack. Pick a temporary folder. Once the extraction has completed look in the folder and find HAL.DLL.SOFTEX for single processor systems or HALMPS.DLL.SOFTEX for multiprocessor systems.
    Warning: If your system is using a different HAL (like many Dell or Compaq systems) the Softex HAL will most likely not work properly.
  3. Copy the softex HAL to your \WINNT\System32\ folder
  4. Rename the file to HAL2.dll
  5. Open BOOT.INI on your system partition with notepad. You may need to change the files attributes to remove the read-only and/or hidden tags.
  6. Change the entry that you normally use to boot your NT installation so that the switch /hal=hal2.dll is appended to the end. For example:
         [boot loader]
         [operating systems]
         multi(0)disk(0)rdis(1)partition(1)\WINNT="Windows NT Workstation Version 4.00" /hal=hal2.dll
         multi(0)disk(0)rdis(1)partition(1)\WINNT="Windows NT Workstation Version 4.00 [VBGA mode]" /basevideo /sos
  7. The registry needs to be updated to tell Windows NT that it can now use the Software Power Off option. Open the registry with RegEdit and navigate to the key:
    HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon
    Find the valuename "PowerdownAfterShutdown" and change its valuedata to "1". If the valuename doesnt exist you will need to add it.
  8. Delete the folder of files extracted from the service pack.
  9. Reboot the machine and the new Software Power Off features should be available