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Why is it that I see an A: drive and a C: drive but not a B: drive?
Is there a reason why the disk partitions start at C? And is it possible to change that letter designation?
cdb
Posted 2009-09-17T10:11:38.597
Reputation: 989
What happened to the B: drive in Windows and why does the hard drive default to C?
Answers
63
Because back in the day of floppy disks, there were either two physical floppy drives (A: and B:), or just one physical floppy drive (A:) with one emulated (B:) so you could copy from disk to disk by exchanging disks every few hundred KB.
Andrew Arnott
Posted 2009-09-17T10:11:38.597
Reputation: 1 151
@TankorSmash Windows has always allowed installing to drives other than C:. If you start install from an existing operating system, the drive mappings get preserved. – kinokijuf – 2014-11-25T21:59:04.503
11@Macha Not older. Badly written. – kinokijuf – 2012-01-27T13:42:45.340
Can we change it ? – ukanth – 2009-09-17T10:15:36.637
16The tradition, or make C: become B:? In Windows' Disk Management console, you can in fact assign hard drives the B: drive letter. But you can't reassign the drive letter of the system drive (usually C:) because the OS would go crazy if its own drive letter changed. – Andrew Arnott – 2009-09-17T10:17:40.970
The GUI won't always allow you to assign A or B to volumes, but DISKPART will. Just SELECT the correct disk/volume then call ASSIGN LETTER=B and your volume will use the new letter. – Goyuix – 2009-09-17T12:32:40.223
1Way back when, there was no such thing as an emulated floppy drive, and hard disks were expensive. Computers would normally come with two floppy drives. One of the real big complaints with the early Macintoshes was that they had only one floppy drive, and no hard drive. – David Thornley – 2009-09-17T14:22:18.317
By the way: C: is traditionally the first hard drive, but it does not need to be the system drive, you can happily install Windows on F: or I:, it's just hard (if not impossible) to change the Windows Drive Letter after installation. – Michael Stum – 2009-09-21T09:54:40.800
2And some older programs assume C: (a) exists and (b) contains Program Files. – Macha – 2010-01-19T08:02:07.710
9
The A and B slots are very useful when you want to give a particular removable device the same drive letter each time it's inserted. Windows will never assign A or B to a device, but if you assign A or B to a device using Disk Manager, that drive letter will be assigned on future inserts.
I keep my source control database on a USB key so I can transfer it between multiple machines, and always assign it to B because I know that drive letter will be available on every machine. Finding this trick simplified my life greatly.
Roger
Posted 2009-09-17T10:11:38.597
Reputation: 1 407
I keep my Zip drive on B: (yes, I have a Zip drive ;-) – kinokijuf – 2012-01-27T13:39:42.133
always available... unless your answer gets accepted! – Mikeage – 2009-09-18T06:58:47.497
1-1, that's not why. – hasen – 2009-09-18T10:29:35.667
2Wouldn't be available if you plugged it into my machine. I have 2 floppy drives... :-) – Brian Knoblauch – 2009-09-18T11:46:26.853
Exception noted. :) – Roger – 2009-09-18T18:16:20.527
2
Can we change it ?
Sort of. Some RAM disk drivers and USB tools allow to assign the long lost drive letter B:.
2Some of us still actually have B: drives in our machines. I've got so many floppy drives laying around that I usually just go ahead and throw 2 in the boxes I put together. Surprisingly, it actually comes in handy from time to time! – Brian Knoblauch – 2009-09-17T12:15:10.953
2What do you store on floppies that is still readable nowadays? – Anthony Giorgio – 2009-09-17T12:27:23.877
@Brian: i hate to break it to you, but you are an exception to the rule, and a rather rare one at that. :) – None – 2009-09-17T14:05:32.683
I have a (working) PDP-11 in a back room that has a working 8" floppy drive and a 9-track tape drive. I also keep a few PCs around with working stale drives and OS installs. It does come in handy. – RBerteig – 2009-09-18T08:06:42.040
1Still have to put drivers on floppies for OS installs sometimes (when hard drive driver required). Also use for moving small files around between machines that don't have free (or working) USB ports. Lots of little random stuff that us programmer/sysadmin people run into on a regular basis that a typical computer user may never encounter. – Brian Knoblauch – 2009-09-18T11:49:04.243
but hardly ever those 360/720 kb 5 1/2 floppies used in what was commonly known as the B; Drive. :) – None – 2009-09-18T13:22:16.973
1
You can map a drive as B: if you want. Under computer management, go to storage/disk management. Right click the drive you want and choose "change drive letter/paths" You should be able to select B: as an option.
takanara
Posted 2009-09-17T10:11:38.597
Reputation: 111
0
Disk Manager (part of Computer Manager) will allow you to assign 'B' to one of your drives.
uSlackr
Posted 2009-09-17T10:11:38.597
Reputation: 8 755
0
I use the B drive for mapping network drives when I've run out of other letters (surprisingly easy to do with USB hubs and such).
Rich Seller
Posted 2009-09-17T10:11:38.597
Reputation: 803
I really don't see why people map drives at all anymore. Full network paths can be added sort of like "favorites" to your network places. Then, you can just select those instead of having to remember exactly where a particular drive letter points to. I use tons of network drives, yet only have a single mapped drive setup (to support a legacy app that can't handle UNC paths). – Brian Knoblauch – 2009-09-18T11:50:47.937
1If you're into the command-line, the drive letters are very quick to type. So, as long as your memory is good, you can save many keystrokes. – Chris W. Rea – 2010-01-07T02:39:24.933
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My Windows XP box at the office has no C drive either. There was a bug in the text-mode setup version I installed from that was triggered by having a Zip drive (think 100 MB floppy) installed when running setup, resulting in Windows XP installed on drive E.
I've found it entertaining (and even occasionally handy) to have no C drive. Quite a few application installers have shown "quirks" when faced with no drive C at all.
RBerteig
Posted 2009-09-17T10:11:38.597
Reputation: 3 235
And you can always use subst to create a virtual drive C if something truely requires it. subst c:\ E:\ – Jack B Nimble – 2011-05-09T20:03:56.917
@Jack, I kept a couple of network shares all set and ready to go to net use as C:. One was for a very stale product I was stuck maintaining that required some parts of itself be located in folders right at the root of C:. It was really convenient to not actually have a C: of my own for that project. These days I would just set up a virtual PC to develop and test inside, of course. – RBerteig – 2011-05-09T20:21:19.453
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I've seen Softgrid (now called Microsoft Application Virtualization (App-V) version 4.5) installs which use the B drive as it's hidden drive... It uses the drive to store the applications to run.
Here is how to do that: http://social.technet.microsoft.com/Forums/en-US/appvbeta/thread/d9d46885-d136-4ace-9cd9-3b881322b86a
jeah subst isn't a good idea but if you are on XP or older and need to change the drive letter to B: then go to HKEY_LOCAL_MACHINE\SYSTEM\MountedDevices and change \DosDevices\Q: to \DosDevices\B:.
Davy Landman
Posted 2009-09-17T10:11:38.597
Reputation: 4 194
-2
A: is for 3.5 floppy drives, B: was for 5.25 drives, noone uses 5.25 anymore so B: is no longer assigned.
acme64
Posted 2009-09-17T10:11:38.597
Reputation: 402
Sorry, not correct. A: and B: can be any combination of BIOS-supported drives/sizes/capacities. – Linker3000 – 2011-05-03T19:22:33.460
of course it can, any letter can be any drive you'd like. but by default it's as i said. – acme64 – 2011-05-13T00:56:05.187
Have to disagree - there was no published standard that defined that as the default position. – Linker3000 – 2011-05-13T13:10:16.467
1and yet, that's how a lot of system where setup – acme64 – 2011-05-14T02:01:13.530
2
Also directly related - What are the Windows A: and B: drives used for?
– Ƭᴇcʜιᴇ007 – 2011-09-03T00:12:53.117