can i install windows 10 onto a usb

NavyLCDR said:

Yes, it is set up as MBR and legacy booting. I used the WinToUSB program. I made 3 partitions. Part 1 was the "system" partition to hold the boot files, set as active. Partition 2 was for Windows 10 Pro 64-bit. Partition 3 was for Windows 10 Home 32-bit. The first install went as expected, selected Part 1 for the system partition for the boot files, partition 2 to install the OS to.

Then when I tried to install the second OS, I originally tried the same thing, Part 1 as the system partition and part 3 to install the OS to. WinToUSB complained that there was already an OS installed. So I changed it to part 3 for both the system partition and the OS partition, and that went fine, but that set part 3 as active.

I then manually changed back to part 1 as the active partition. Booted it into Windows 10 Pro, and used BCDBOOT command to add the Windows 10 Home 32-bit to the boot menu.

I was then going to do the same thing to add Windows 7 to a 4th partition in exactly the same way, and I actually got it installed, added to the boot menu, and booted into it, but after I created a user account Windows 7 complained about not starting the login server and could load user profile. I didn't really want to mess with it too much, so I just scrapped the idea of adding Windows 7 to it.

Ah I see that now. Thanks for this - I wonder if it would be possible with UEFI - I shall have to experiment now you have given me the basic idea☺.

Actually, your approach would make a neat tutorial😇.

NavyLCDR said:

Yes, it is set up as MBR and legacy booting. I used the WinToUSB program. I made 3 partitions. Part 1 was the "system" partition to hold the boot files, set as active. Partition 2 was for Windows 10 Pro 64-bit. Partition 3 was for Windows 10 Home 32-bit. The first install went as expected, selected Part 1 for the system partition for the boot files, partition 2 to install the OS to.

Then when I tried to install the second OS, I originally tried the same thing, Part 1 as the system partition and part 3 to install the OS to. WinToUSB complained that there was already an OS installed. So I changed it to part 3 for both the system partition and the OS partition, and that went fine, but that set part 3 as active.

I then manually changed back to part 1 as the active partition. Booted it into Windows 10 Pro, and used BCDBOOT command to add the Windows 10 Home 32-bit to the boot menu.

I was then going to do the same thing to add Windows 7 to a 4th partition in exactly the same way, and I actually got it installed, added to the boot menu, and booted into it, but after I created a user account Windows 7 complained about not starting the login server and could load user profile. I didn't really want to mess with it too much, so I just scrapped the idea of adding Windows 7 to it.

I managed to do the same with UEFI. If anything it is slightly simpler as you do not have to mark partitions active.

It took me a while to get the bcdboot syntax correct, and struggled until I realised I had to boot to a Winpe environment but go there.

Basic steps

1) partition hard drive using script like this

rem == CreatePartitions-UEFI.txt ==
rem == These commands are used with DiskPart to
rem create two partitions needed for wintousb
rem for a UEFI/GPT-based PC.
rem ============
rem adjust disk number to suit eg if one internal drives most likely n=1, 2 drives n=2 etc
rem use list disk first
rem WARNING if you do not get this right you could wipe wrong disk
select disk 2
clean
convert gpt
create partition efi size=360
format quick fs=fat32 label="System"
assign letter=S
rem == Create the Windows partition ==========
create partition primary
format quick fs=ntfs label="Windows"
assign

2) install windows (10 in my case) using wintousb 3.0

3) shrink windows partition from disk management and create new partition and initialsie an ntfs volume (could have done it in diskpart but then I would have had to mess around with sizes)

4) install next windows (8 in my case) in new partition overwriting EFI partition

5) boot from win 10 usb drive, get to command prompt and use bcdboot command to add first OS boot entry back (which was overwritten).

I then went all round the houses doing adding virtual hard drives as well which also worked.

Once I worked out steps and syntax of commands, it worked very well.

NavyLCDR said:

Cool! Thanks for the update! I'm replacing my last legacy BIOS laptop this week, so I can go with 100% UEFI next week. Getting myself an Intel i7-4702HQ based 17.3" ASUS. Looks like it is going to be fun replacing the 2TB hard drive with a 500GB SSD, though, since the whole top keyboard/bazel has to come off.

Forgot to mention you have to wipe efi partition and create blank between installs. I used minitool partition manager.