The Great Debate

My friend and I are having a debate over the following question,who is right?
The question is--Can you have your OS on a usb external drive?
1).I say no because I think that windows activates the usb ports -(by loading drivers or some other way),so without the usb ports active at startup you can never get to the OS.
2).He says yes you can because the usb ports are activated by the motherboard or bios so you can get to the OS.

Most modern computers are able to boot from USB. So you can boot from a USB flash drive (thumb drive) or USB external drive as long as you've set up the USB drive to be bootable. Check your computer's BIOS to see if it allows booting from USB. If it doesn't, there's not much you can do.

A bigger question is whether you can get "Windows" (as opposed to Linux) to boot from an external drive. XP seems to be possible. Vista and 7 are more problematic.

If you want to boot from XP on a USB flash drive, you may want to check one of the how-to's online, like this one
http://www.poweriso.com/tutorials/how-to-make-winxp-bootable-usb-drive.htm

According to this, there are some hacks/workarounds to getting Vista and Windows 7 to work. It's easier with XP.
https://neosmart.net/forums/showthread.php?t=3263

Short answers are "you're both right" and "it depends."

Thanks Jenny100. I don't want to do it but I wanted to know the answer.

Good answer, Jenny - it depends. Supposedly the Enterprise version of Windows 8 has a "Windows to Go" option which allows you to boot it from a 32 GB or 64 GB flash drive as long as the motherboard BIOS supports it.

My answer was going to be if the computer is set up to scan ports to find the bootable drive. But as was said setting within the BIOS would have to be set for this to happen.