What switches can be used in boot.ini?

A. The boot.ini file has a number of lines and some of these relate to the Windows NT Operating system, e.g.

multi(0)disk(0)rdisk(0)partition(2)\WINNT="Windows NT Workstation Version 4.00"

There are a number of switches that can be appended to the Windows NT startup line to perform certain functions. To edit the file perform the following

  1. Start a command session (cmd.exe)
  2. Modify the attributes on the file c:\boot.ini to make the file editable
    attrib c:\boot.ini -r -s
  3. Edit the file
    edit c:\boot.ini
  4. Once finished save the file and reset the files attributes
    attrib c:\boot.ini +r +s

The switches that can be added are as follows

/3GB New to Service Pack 3. This causes the split between user and system portions of the Windows NT map to become 3GB for user applications, 1GB for System.
To take advantage of this the system must be part of the NT Enterprise suite and the application must be flagged as a 3GB aware application.
/BASEVIDEO The computer starts up using the standard VGA video driver. Use this if you have installed a graphics driver that is not working.
/BAUDRATE Specifies the baud rate to be used for debugging. If you do not set the baud rate, the default baud rate is 9600 if a modem is attached, and 19200 for a null-modem cable.
/BOOTLOG Makes 2000 write a log of the boot to the file %SystemRoot%\NTBTLOG.TXT
Windows 2000 Only
/BURNMEMORY= Makes NT forget about the given amount of memory in MB. If /burnmemory=64 was given then 64MB of memory would be unavailable
/CRASHDEBUG The debugger is loaded when you start Windows NT, but remains inactive unless a Kernel error occurs. This mode is useful if you are experiencing random, unpredictable Kernel errors.
/DEBUG The debugger is loaded when you start Windows NT, and can be activated at any time by a host debugger connected to the computer. This is the mode to use when you are debugging problems that are regularly reproducible.
/DEBUGPORT= comx Specifies the com port to use for debugging, where x is the communications port that you want to use.
/FASTDETECT Specifying FASTDETECT causes NTDETECT to skip parallel and serial device enumeration for a boot into Win2K, whereas ommitting the switch has NTDETECT perform enumeration for a boot into NT 4.0. Win2K setup automatically recognizes dual-boot configurations and sets this switch for BOOT.INI lines that specify a Win2K boot.
Windows 2000 Only
/HAL=<hal> Allows you to override the HAL used, for example using a checked version
/INTAFFINITY Sets the multiprocessor HAL (HALMPS.DLL) to set interrupt affinities such that only the highest numbered processor in an SMP will receive interrupts. Without the switch the HAL defaults to its normal behavior of letting all processors receive interrupts.
Windows 2000 Only
/KERNEL=<kernel> Same as above but for the kernel
/MAXMEM:n Specifies the maximum amount of RAM that Windows NT can use. This switch is useful if you suspect a memory chip is bad.
/NODEBUG No debugging information is being used.
/NOGUIBOOT When this option is specified the VGA video driver responsible for presenting bit mapped graphics during Win2K's boot process is not initialized. The driver is used to display boot progress information, as well as to print the Blue Screen crash screen, so disabling it will disable Win2K's ability to do those things as well.
Windows 2000 Only
/NOSERIALMICE=\[COMx | COMx,y,z...\] Disables serial mouse detection of the specified COM port(s). Use this switch if you have a component other than a mouse attached to a serial port during the startup sequence. If you use /NOSERIALMICE without specifying a COM port, serial mouse detection is disabled on all COM ports.
/NUMPROC=n Only enables the first n processors on a multiple processor system
/ONECPU Only use the first CPU in a multiple processor system
/PCILOCK Stops Windows NT from dynamically assigning IO/IRQ resources to PCI devices and leaves the devices configured by the BIOS.
/SAFEBOOT: This is an automatic switch which NTLDR should complete for you when you use the F8 menu to perform a safe boot. Following the colon in the option you must specify one of three additional switches: MINIMAL, NETWORK, or DSREPAIR. The MINIMAL and NETWORK flags correspond to safe boot with no network and safe boot with network support. The safe boot is a boot where Windows 2000 only loads drivers and services that are specified by name or group in the Minimal or Network Registry keys under HKLM\System\CurrentControlSet\Control\SafeBoot. The DSREPAIR (Directory Services Repair) switch causes NT to boot into a mode where it restores the Active Directory from a backup medium you present.

An additional option that you can append is "(ALTERNATESHELL)". This tells NT to use the program specified by HKLM\System\CurrentControlSet\SafeBoot\AlternateShell as the graphical shell, rather than to use the default which is Explorer.
Windows 2000 Only

/SOS Displays the driver names while they are being loaded. Use this switch if Windows NT won’t start up and you think a driver is missing. This option is configured by default on the \[VGA\] option on the boot menu.
/WIN95 This switch is only pertinent on a triple-boot system that has DOS, Win9x and Windows NT installed. Specifying the /WIN95 switch directs NTLDR to boot the Win9x boot sector stored in BOOTSECT.W40. See Microsoft KB Article Q157992 for more information.
/WIN95DOS This switch is only pertinent on a triple-boot system that has DOS, Win9x and Windows NT installed. Specifying the /WIN95DOS switch directs NTLDR to boot the DOS boot sector stored in BOOTSECT.DOS. See Microsoft KB Article Q157992 for more information.
/YEAR= Specifying this value causes NT/Windows 2000 core time function to ignore the year that the computer's real-time clock reports and instead use the one indicated. Thus, the year used in the switch affects every piece of software on the system, including the NT kernel. Example: /YEAR=2005. Note: this option is only available on NT 4.0 Service Pack 4 and Windows 2000.

You can then edit the boot.ini file and either add Windows NT startup entries or modify existing entries, for example you could add a debug entry in the file as follows

multi(0)disk(0)rdisk(0)partition(2)\WINNT="Windows NT Workstation Version 4.00 \[debug\]" /debug /debugport=com2

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