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Q170756: Available Switch Options for Windows NT Boot.ini File

Article: Q170756
Product(s): Microsoft Windows NT
Version(s): 3.51,4.0
Operating System(s): 
Keyword(s): kbsetup
Last Modified: 06-AUG-2002

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The information in this article applies to:

- Microsoft Windows NT Workstation versions 3.51, 4.0 
- Microsoft Windows NT Server versions 3.51, 4.0 
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SUMMARY
=======

When you start Windows NT, there are many different switches that can be added
to the Boot.ini file that will modify the way Windows NT loads. For additional
information about the Boot.ini file, click the article number below to view the
article in the Microsoft Knowledge Base:

  Q102873 Boot.ini and ARC Path Naming Conventions and Usage


MORE INFORMATION
================

The following are the different switches that can be added to the Boot.ini
file:

/3GB
----

Enables user-mode programs to access 3 GB of memory instead of the usual 2 GB
that Windows NT normally allocates to user-mode programs. It moves the starting
point of kernel memory to 3 GB. This switch is used only in the Windows NT
Server Enterprise Edition of Windows NT with Service Pack 3.

For additional information, click the article number below to view the article in
the Microsoft Knowledge Base:

  Q171793 Information on Application Use of 4GT RAM Tuning

/BASEVIDEO
----------

The /basevideo switch forces the system into standard 640x480 16-color VGA mode.
This is used to enable the system to load if the wrong video resolution or
refresh rate had been selected.

For more information, please see the following Microsoft Knowledge Base article:

  Q126690 Windows NT 4.0 Setup Troubleshooting Guide

/BAUDRATE=nnnn
--------------

This switch sets baudrate of the debug port. If you do not set the baud rate, the
default baud rate is 19,200. 9,600 is the normal rate for remote debugging over
a modem. This also enables the /debug switch. For example, /BAUDRATE=9600

For more information on modem configuration, please see the following Microsoft
Knowledge Base article:

  Q148954 How to Set Up a Remote Debug Session Using a Modem

For more information on null modem configuration, please see the following
Microsoft Knowledge Base article:

  Q151981 How to Set Up a Remote Debug Session Using a Null Modem Cable

/CRASHDEBUG
-----------

Enables the COM port for debugging in the event that Windows NT crashes. This
enables you to use the COM port for normal operations while Windows NT is
running, but converts the port to a debug port if Windows NT crashes (to enable
remote debugging).

For more information, please see the following Microsoft Knowledge Base article:

  Q151981 How to Set Up a Remote Debug Session Using a Null Modem Cable

/DEBUG
------

The /debug switch enables the kernel debugger. This enables live remote debugging
of a Windows NT system through the COM ports. Unlike /crashdebug, /debug uses
the COM port whether or not you are debugging.

For more information on remote debugging, please see the following Microsoft
Knowledge Base article:

  Q121543 Setup for Remote Debugging

/DEBUGPORT=comx
---------------

The /debugport=comx switch selects a COM port for the debug port (com1, com2,
com3...) DEBUGPORT defaults to COM2 if it exists, otherwise it uses COM1. This
also enables the /debug switch. For example, /DEBUGPORT=COMx where x is the com
port.

For more information, please see the following Microsoft Knowledge Base article:

  Q151981 How to Set Up a Remote Debug Session Using a Null Modem Cable

/HAL=filename
-------------

Enables you to define the actual hardware abstraction layer (HAL) to be loaded at
startup. This switch is useful in trying out a different HAL before renaming it
to hal.dll. This switch is also useful when you want to try booting between
multiprocessor and single processor mode when used in conjunction with the
/kernel switch. For example, /HAL=halmps.dll this loads the Halmps.dll in the
System32 directory.

/KERNEL=filename
----------------

The /kernel=filename switch enables you to define the actual KERNEL to be loaded
at startup. This is useful in switching between a debug enabled kernel full of
debugging code and a regular kernel. It is also useful for forcing Windows NT to
load a specific kernel. For example, /KERNEL=ntkrnlmp.exe. This switch command
loads the Ntkrnlmp.exe in the System32 directory.

/MAXMEM=nn
----------

The /maxmem=nn switch selects the amount of memory Windows NT detects and can use
at startup. This setting should never be set to less than 12. This option is
good for checking for bad memory chips. For example, /MAXMEM=12

For more information, please see the following Microsoft Knowledge Base article:

  Q108393 MAXMEM Option in Windows NT Boot.ini File

/NODEBUG
--------

This switch disables the kernel debugger. The switch turns off debugging. This
can cause a blue screen if a piece of code has a debug hardcoded breakpoint in
its software.

/NOSERIALMICE:comx
------------------

This switch disables the mouse port check for this com port. For example,
/noserialmice:comx, where X is the number of the serial port. Ports may be
separated with commas to disable more than one port. If no serial port is given
then all ports are disabled for mouse devices.

This is used with uninterruptible power supply (UPS), like those from American
Power Conversion brand (APC), that connects to a serial port. If this option is
not available when Windows NT starts, and Windows NT tries to detect a mouse on
this port, then the UPS will accidentally start its shutdown mode.

For more information, please see the following Microsoft Knowledge Base article:

  Q131976 How to Disable Detection of Devices on Serial Ports

/NOLOWMEM
---------

This loads the entire system (drivers, pools, programs, etc.) above 4 GB. This
only works for Windows 2000 Advanced Server and Datacenter Server.

/NUMPROC=
---------

This switch sets the number of processors that Windows NT will run at startup.
This will help test out performance problems and defective CPUs. For example,
/NUMPROC=3

/PAE
----

Enables support for 8 GB of memory for Windows 2000 Advanced Server and for 32 GB
of memory for Windows 2000 Datacenter Server.

/PCILOCK
--------

This switch prevents the HAL from moving anything on the PCI bus. The I/O and
Memory resources are to be left exactly as they were set by the BIOS.

For additional information, click the article number below to view the article in
the Microsoft Knowledge Base:

  Q148501 Preventing PCI Resource Conflicts on Intel-Based Computers

/SOS
----

The /sos switch causes the loader to print the name of loaded modules. When
Windows NT comes up instead of displaying dots while the devices load, Windows
NT will show the actual names of the drivers as they load.

For more information, please see the following Microsoft Knowledge Base article:

  Q99743 Purpose of the Boot.ini File

/ONECPU
-------

This switch is part of Compaq's HAL. The switch tells Windows NT to use only 1
CPU at startup. This will enable you to run a single CPU in a multikernel
configuration. For example, /ONECPU.

For more information on other Boot.ini switches that do not relate to Windows NT,
please see the following Microsoft Knowledge Base article:

  Q157992 How to Triple Boot to Windows NT, Windows 95, and MS-DOS

/WIN95
------

The /win95 switch loads bootsec.dos.

/WIN95DOS
---------

The /wind95dos switch loads bootsec.w40.


Additional query words: boot switches

======================================================================
Keywords          : kbsetup 
Technology        : kbWinNTsearch kbWinNTWsearch kbWinNTW400 kbWinNTW400search kbWinNT351search kbWinNT400search kbWinNTW351search kbWinNTW351 kbWinNTSsearch kbWinNTS400search kbWinNTS400 kbWinNTS351 kbWinNTS351search
Version           : :3.51,4.0
Issue type        : kbinfo

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