Changing the Windows C: Drive to Any Letter 

I would advise app makers to use the environment variable %homedrive%:\ instead of C:\

Has science gone too far?

I am a software developer, and most of my apps use predefined path locations(since it's more convenient). But as soon as I watched this video, I rushed to quickly change all my libraries to work with %systemdrive% instead

U can always make a small C drive and fill it up with symbolic links to the A drive. That way the programs using C drive by default will be redirected to A

There are also special versions of Windows where the default letter for the installation volume is A. Back in the MS-DOS days, the most popular series of PCs in Japan was NEC's PC-9800 series of PCs. These computers were not compatible with standard MS-DOS and had a special version of DOS that was compatible with those computets, but where the boot drive would always be the A drive (so it didn't matter if you installed DOS on a hard drive or if you booted from a floppy disk, the boot drive was always A). Eventually, versions of Windows would be ported to PC-9800 series computers, and the PC-9800 editions of Windows would also by default use A as the letter for the installation volume

A fun fact is that most viruses are hardcoded to use C: drive as System, so if you do that stuff, you will get fewer problems with viruses

This could potentially bypass some malware also that might be hard coded to use C: or assume the O/S is there.

when it comes to windows ,honestly you are the very best, hands down..please keep this stuff up because it is great to know these things. thank you

Finally a good tutorial thats not outdated

It's been a long time since I watched you man, you're still kicking🔥

I think enderman made a video in which he showed that any Unicode Charakter is valid as a drive letter in Windows. Would be interesting to see if you can install Windows to a drive thats called 1: or something...

What a time to come across this vid. I'm at the moment using the free version of 'AOMEI' Partition Assistant' (Standard Edition.) I'm a bit blown away by it. One of the options is to 'letter' the partitions. A-Z is available and takes about 5 seconds. I'd suggest downloading it just for a look.

The installer for XP and earlier used the MS-DOS rules for assigning drive letters. So if you tried to install XP on, for example, a logical drive in an extended partition, you’d end up with it installed on D: or E:. Only in Vista did they start using the selected install partition as C: no matter what.

Woahhhh! They said it was impossible to install Windows in a drive set in a different letter. Anyways, you finally made the right choice for the thumbnail. The thumbnail made it more intriguing. And I was impressed!

This would be an interesting experiment to see how much hard coding of windows path programs have done. Also some virus may not work if it is hard coded to assume c drive.

Well now I have another idea of how I can confuse my friends. First I made it look like my computer somehow "downgraded" from Windows 10 to 7 (it was a windows 7 vm that was in full screen mode that I made for fun). Now I can't imagine how they'll react to not seeing a different drive letter on a vm.

Back in the day, the A and B drives were for the two floppy (the real kind) drives were assigned to them by default as they came before hard drives (IIRC). So by default, the C drive then represented the primary hard drive going forward and as an industry, everyone stayed with that for compatibility.

I changed the main drive to my work system to the "D" drive, an external drive about 8 years ago. I also installed an internal SSD for the boot drive. The boot drive was still designated as "C" and contained ONLY the OS. All other functions, programs, apps and data took place on the "D" drive. It did require a little more work and attention to detail but for my situation at the time, it was needed and worked.

Thanks for the video dude! You're the GOAT

I had WinNT on D: a long while ago. Win98 on C: (because of an early MP3-player that needed Win98 to be loaded through a parallel port, which couldnt'd be done in NT). When I removed C: a bit later, I ended up with D: for the OS, and E: for the data. I had a virtual C: mounted somewhere on D:, so programs that insisted on C: did even work...

Yes i was waiting so long

3:34 (idk if you know this) but pro tip, to save time instead of doing "list volume" or "list partition", do "lis vol", or "lis par", it still works, and saves time, this applies to other commands in diskpart

There are very common-sense reasons for doing this: Anybody who wants to install multiple OSs for a multi-boot system needs it. I have a Win7 partition that I'm still rockin', but decided too many devs have moved to the spyware-laden 11. Yet, installing it from a USB kept insisting on calling the drive it was on "C:". This hack works, and allowed me to install on E:. Working on Win11 22H2. Some software manufacturer. How many OSs in history made you get an expensive Server edition in order to install anywhere else than C:??? Epic hack, for those who need it, ThioJoe!

Thanks I’ve always wanted to have my system installed on a floppy drive

Back when Windows was a graphical shell running on DOS I always installed DOS on C and Windows on D. It just seemed to run better and it kept the two operating systems separate.

Amazing Video nice i was wondering doing this and you readed my mind

I used to have Windows 9x and NT family (2000 or XP). When you already have a Windows installed and start installing a newer version from Windows rather than booting from CD/DVD/USB, the new installation would use D: drive. I may still work with newer versions. Although it's not an arbitrary drive letter in that case compared to what Thio demonstrated.

Back in the 1990's playing around I figured out how to change the drive letter in Windows, they thought to myself this probably isn't a good idea - and it wasn't.

If you're looking for ideas of tutorial videos, like you do so well. Maybe a video on how to rename your User "name" folder under the Users folder. Even though you can do it as the owner, it doesn't rename the actual folder under the user folder. Keep up the great videos. Thanks.

Thanks Thio!

Thio is a legend

I wanted to know answer, now I know the answer! :D Thanks for the video!

hah, always fun to do those kind of work arounds, love em.

I already knew how to set drive letters to A/B, not the system drive, sheesh. This is pretty cool

I once accidentally set the system driver letter to E while cloning a drive to an ssd. It booted after some registry edits. many apps failed to run so I added the C as a 2nd letter for the osdisk and it was fine.

Good video Thio, I didn't know that was possible! Btw can you make a video of "What if you eject and delete the ENTIRE C: drive?", It would be hella cool

Never knew that was even possible and never actually thought anything of it Cool!

Since first Windows appears i had installed it onto not C: for testing purposes, it is easy as clear water, no special tricks needed, it can be done natively just by a personal partitioning at install booting process, with multi-patition, just to ensure C: is in use while install runs from the ISO... so it uses other letter .. and with diskpart i force it to be whatever i wish. That is from more than 20 years ago... and all versiones, including Windows 11. Add: I did publish it the first time i used, also i did publish how to boot every Windows without any physical Primary partition on any physical storage (using Grub2, Grub, Memdisk, VHD (to hold the boot primary partition), etc...only having one Extended partition for each Windows .. and at boot time be able to choose what Windows to boot ... having only one physical disk/storage.

I did this to every clients computer back in the 98-xp days since many viruses were hard coded for c and couldnt infect without it, if any apps that failed without it, i just changed the shortcut to run a script with subst temporarily and was never a problem after that

LOL That intro though.... very alien-documentary-like. 😂😂

This path "mounted devices" on registry was helpfull when my cloned (dd tool used ) install didnt want to go to desktop ( black screen only loading icon stuck) . the solution was to erase all things inside there with remote registry , and re-create an EFi folder .

This is MAD science!

No one: Not a single sole: Literally not human ever: ThioJoe: Today I'm going to show you how to change your C: Drive to another letter 🤣

I remember attempting to modify this when Windows was installed on D: instead of C: on a server. Drove me nuts. Wish MS would abandon drive letters that date back 40 yrs ago.

As an aside, the last time I used diskpart, I accidentally deleted a volume and diskpart did not give me a warning or any chance to cancel the operation. I had to use recovery software to get my data back. Bear that in mind if you use diskpart on a system where there is important data being stored

I'd love to know how it can happen that bcdedit does not show the "correct" drive letter if you did *not* resize or move the partition. Also, I'd like to know what happens if you do *not* fix that (does it boot into recovery and change the letter back to C:?) In the BCD file, usually (at least when doing a clean install) there is not stored any drive letters, but instead partition IDs and partition offsets, and bcdedit will convert to the actual drive letter once you view it (you can test this by booting WinPE (or Windows Setup), change drive letters (they won't persist across reboot) and look at bcdedit and the drive letters will appear differently. But yes, I did not know this method, but like it better than running X:\sources\setup from inside an already installed Windows (which, up to at least Win10, also results into a changed drive letter). I often have to edit DosDevices when cloning your disk to a different media type/size, so I understand why this works. I also fear that these kind of hacks might not survive a version upgrade (or cause problems during settings migration). But for a nice test machine (or some "Windows To Go"), I'd totally go for it.

Thanks, TJ~

Maybe you can use the subst command for the programs that need the c drive

Way back in the day I did a brute force change. Think I did it later with some version during setup.

Thats pretty cool :D

My assumption was that, even in Win10+, it was _intended_ to be hardcoded (for backward compatibility reasons) that C: _must_ be the OS drive, A: and B: are reserved for floppy drives (good luck finding one these days), D: _must_ be either a CD or DVD drive or a mounted .iso file (I play a lot of older games that have CD-required DRM, and they won't run unless the disc-in-drive is mounted to D:, or I've created an iso of the CD, reassigned the physical drive to a different letter, and powershelled Mount-DiskImage to have the iso mount to D:...), and E: through Z: could be whatever you want them to be. (I believe X: is also a system-reserved mount point, but who would fill up E: through W: and _need_ X:?)

Thanx for the video. When I installed Win 11 on a second partition it haves it's self drive i: rather than drive C:

Now, what happens if you plug a floppy drive into a Windows machine thats installed to a:? Will it automaticly show up as the B: drive?

Can you do this on the current installation:insert media>boot media>repair boot>cmd>registry editor >change name>restart

Fun fact: you can install windows to any directory on C volume by manually applying the image (even C:\con)

I can't wait for the calls from my clients asking me to repair their systems. You're making me money! Thanks.

Did this once back in the XP days, one thing to add regarding A: and B: drives is that they get excluded completely from windows search indexes, at least up to Windows 7, I didn't try any further. So avoid them unless you want this to happen. :D

what if you use a 3rd party program to change D: to A: then use one of those programs specialized in moving content from a drive to another one, you move the content of C: drive to the A: drive then you can just change the name of C: to D: or any other letter

Finally you changed the wallpaper lol

I changed disk letter to another with some utility which replace letter in registry. But it works only in clean system.

Doing the lord's work

Long long ago I installed DOS to netboot. Some PCs had a local hard drive with C and D partitions, some not. So everything from the OS went into E.

I have done this by accident because sometimes I install Windows from inside Windows via /sources/setup.exe. Windows just sets up with the drive letter as mounted on the running system. So when I need to install Windows to a partrition, set as D:, it will setup as D: This has sometimes caused problems, and sometimes just been cool to see. I really advise program makers to install to %systemdrive% instead of C:\

I literally thinking about the same and searched for the same on RU-vid today, and here ur

I remember an old PC bios I had that could do, set the boot drive C: E: F: G: (I think it was a award-bios), didn't use it much, the one think a very liked, I never seen on any of my later PC's was your could set password as the boot on power key, so the PC would play completely dead until the right key presses for the password where pressed, I realy miss that, not so much for the security, you could power up the box only pressing key on the keyboard, no stretching to down find the PC boxes power button?

Well good job, you somehow made it harder for malware to store stuff in temp.

I once did a dualboot of "Windows XP X64" and "Windows XP" and X64 version used E: Drive for main installation automatically

I can confirm that adobe lightroom shows A: drive with the latest version of Lightroom. I have the letter A set to my ssd which has my lr catalog and all the photos.

Been there done that (ish), one of my x-wifes computers were divided to an extremely small C: and a huge D: "for data" as the support said, however there were no room to install programs to C, so I had to try to D:, and run into the same kind of problems as adobe lightroom. Don't actually recall which program, but I gave up and wiped, clean installed onto all disc is C:

Interesting video

Hey guys and ThioJoe, I use my PC mainly for gaming (both native games and emulators), has Windows 11 reached a point where I should upgrade to it instead of sticking to 10 until the end of its support ? Btw, I really like videos like this where you show us how to do stuff that normally we wouldn't be able to do just to goof around.

@ThioJoe is it possible to download windows 11 on an unsupported pc that is over 6 years?

Quick question why theres no other way to change letter? also why my hard drive dont let me erase all partitions? like dont let me install in the 18tb partition only in the 2 tb partition like why?

You can use this same method with the install disk to sign into a passworded PC that someone has forgotten the password or a found laptop. To change the password to whatever you want. windows security is more of a suggestion than a rule.

Isn't this possible by simply installing windows to an existing empty partition that already assigned with alternate letter? because i'm sure when I did that in the past, it kept the original drive letter that I assigned to that partition. Which in this case was not "C".

Mine boots from an X drive with pre scripted admin in command loading 32 when its a 64 ,also ive found monitoring that was so invasive from keylogger to 1 every choice i had

The official way of doing this is using an unattended install. The unattened install script allows you to setup all the drive letters of your partiion. It requires that you repartition the dtive in the unattended setup so is not suitable for everyone. There is a website that will generate an unattended script file that you place on a windows install usb stick which means the drive will auto install windows erasing everything on any machine that boots it so you need to be extra careful with a usb stick configured for unattended install

What happened to the ai voice translations? I watch all videos in English but still it was fun to change the audio on your videos

What virtual machine system do you use?

A: should be a norm today for the main OS partition since almost nobody have floppy disk readers

came into this video with a Jim quote "I'm gonna skip the how and go straight to the 'why?'"

"You are always vulnerale to viruses". Windows on A letter which would make the path the virus targets change and so would make a lot of scripts unvalid:

Maybe you could fix the "programs assuming there to be a C drive" problem by creating a symlink or something similar to link the root path of C: to A:

I use A: to mount a removable drive and B: to mount a network drive.

How do I switch C and D drives at the same time or merge both drives into C using command prompt? After the last windows 10 update somehow C and D drives were switched so now Windows cannot boot up because it is trying to boot from C drive Volume 1 which is the Recovery drive but now my Windows is on D drive volume 0. I've tried selecting C drive in command prompt booting from USB drive and assigning it a different letter like Z and Diskpart says that it successfully assigned the letter but when I go to list volume it still has Recovery listed as C and main partition listed as D. For some reason it is refusing to change C drive to something else even though it says that it is changed. All partitions are listed as healthy. Bootrec /scanos = 0 total identified windows installations. How do I reverse those 2 for good in command prompt? I haven't been able to find a good article or video on it.

I think you can do this by having an already-formatted drive, selecting that in the windows installer instead of a clean partition. PS: I have accidentally done this before, MS support told me I had to reinstall PPS: This is probably why the person said to "set the letter", It's assumed you aren't using clean drives

I was wandering if you can do more than 1 letter

I'm fine with it using C: as the system drive, but I would still want to use A: and B: as USB drives.

It's very very interesting

When I done I got a 7B BSOD (Windows 7 in a VM)

You can't read minds bruh? Obviously the guy is on another level for the setting a letter part.

well you can still use A: for windows and make C: partition for other programs (instead of D: )

I was able to do this on Windows 7 by running the installer on an existing windows installation and targetting an already formatted ntfs partition. But this doesn't work with the windows 10 installer anymore

What if you set it to Z instead? Numbers overflow and loop around but I don't know about letters

Where did you get the 126GB floppy disk from?

If your windows drive isn't your only drive, than simply set another drive to drive letter C and problematic programs will just install there.

I had a windows installation, with only one drive, which was "D", no A, B, or C drive. Yes, the boot drive was "D." This was accidental, and occurred when I was converting from W7 to W 10. Don't know how it happened, but the conversion had problems, and took several tries.

I'm gonna try this the next time I install Windows 10 as a comeback to Windows. Edit: I don't know whether I can install Windows 11 on my laptop, because the operating system wants a TPM 2.0 chip in that. Another thing, the Windows 11 ISO image is really large actually. I'll just install Windows 11 and try this anyway.

I want to see a Part 2 where you add a floppy drive to this system! 🙂

"Your scientists were so preoccupied with whether they could, they didn't stop to think if they should." ~some dude