Fastdetect boot.ini switch

Fastdetect boot.ini switch

The /fastdetect parameter is used to disable the Windows operating system from detecting specified communications ports during startup.

The /fastdetect switch is used often for security reasons. Having the fastdetect parameter in your boot.ini file prevents your Windows system from unauthorized booting from unsupported device.

That said, the fastdetect parameter will not play any role when using devices known only to the BIOS (not to Windows) with your computer.

What is the benefit of using /fastdetect?

Because the fastdetect switch prevents detection of unsupported devices, it typically results in a faster and more reliable start of your computer.

How and where is /fastdetect user?

The /fastdetect parameter is used in the boot.ini file.

Setting the /fastdetect switch for your server is very easy. Do the following steps:

-> right-click My Computer
-> Properties
-> click the Advanced tab
-> click Settings in the Startup and Recovery area
-> click Edit in the System startup area

This will explore the boot.ini file in Notepad. You can see this in the print screen behind the following link:

3GB setting print screen

Go to the [Operating Systems] section and add the /fastdetect switch to the end of the line that talks about your Windows startup option(s). Save your changes, close Notepad, and then click OK to close all the open dialog boxes.

You need to reboot the computer for the change to take effect.

Note, if you do not specify a communications port behind the /fastdetect switch, this parameter disables detection on all serial and parallel ports.

Fastdetect example

The following is an example of what your boot.ini file might look like. No need to pay attention to the timeout and partition and other parameters, those depend on your particular configuration and setup. Pay attention to the line with the /fastdetect.

[boot loader]
[operating systems]
multi(0)disk(0)rdisk(0)partition(1)\WINDOWS="Windows Server 2003, Enterprise" /fastdetect

Can the FASTDETECT switch really disable all ports?

There is one peculiarity that comes into play with the fastdetect boot.ini option.

The /fastdetect parameter still permits the operating system to detect Plug and Play (PnP) devices on these ports. It prevents detection of unsupported devices.

When testing a port that is hidden from Plug and Play (PnP), you would need to omit the fastdetect switch from your boot process.

Is the fastdetect option available in all Windows?

This option is only available on 32-bit versions of Windows.

By default, your setup adds the /fastdetect parameter to the boot.ini file entries that it creates when you install any of the following operating systems:

  • Windows Server 2003,
  • Windows XP,
  • Windows 2000.

Windows NT 4.0 used the name /noserialmice for a parameter with the same functionality.

Are there any other boot.ini parameters that I should know about?

Yes, you might be interested in knowing about the /3GB switch: 3GB Switch in Windows boot.ini.

The Data Execution Prevention DEP setting can be also implemented in your BOOT.INI file through the NOEXECUTE switch. See the noexecute DEP parameter in boot.ini page for more details.


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