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Using drive letters A: and B: - drawback?


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#1 Dirkk

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Posted 05 May 2015 - 02:54 AM

Can / should I use the drive letters A: and B:?

 

They are not displayed e.g. in the Mini Tool Partition Wizard (before assigning them, after they are), but they are e.g. in the Win 7 drive manager (to partition, change letters, etc.) and Win Explorer. There obviously are programs they are not displayed in (by default).

 

Might that mean there is any drawback to use them?

 

I would use them for an external 2,5" hard drive.


Edited by Dirkk, 05 May 2015 - 03:14 AM.

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#2 Platypus

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Posted 05 May 2015 - 03:28 AM

Microsoft says it's permissible to use them for removable drives (a floppy disk is after all removable media), e.g.:

 

"Drive letters A and B are reserved for floppy disk drives, but you can assign these letters to removable drives if the computer does not have a flppy disk drive."

 

https://www.microsoft.com/resources/documentation/windows/xp/all/proddocs/en-us/dm_drive_letter.mspx?mfr=true


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#3 Dirkk

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Posted 05 May 2015 - 04:04 AM

Many thanks, Platypus,

 

That sounds really good. And I assume it is the same with Win 7 I am using or other OSs higher than Vista.

 

I am wondering if those floppies are still in use...if yes, what for?

 

I hadn't found any useful information besides of that: http://www.howtogeek...rives-used-for/:

 

Less an answer, more of an anecdote. In this Microsoft article, it says:

“You can assign the letters C through Z to each drive on your computer. A and B are usually reserved for floppy disk drives, but if your computer does not have floppy disk drives, you can assign A and B to volumes.”

So when I built a new computer recently with two internal drives, one for the OS and one for data, I thought, hey!, I’ll make my data drive “A”. I felt all rebellious until I discovered that Windows will not index drives lettered A or B. sad.png

Took me quite a while to figure out what the problem was, but I found some other people who suffered the same issue when they used A or B for a [primary] drive. As soon as I assigned that drive a different letter, windows indexed the drive. So much for being rebellious.

 

Many thanks again.


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#4 Platypus

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Posted 05 May 2015 - 05:02 AM

I'm assuming it hasn't changed for Win 7 - my Win 7 laptop offers A and B as possible to change a hard drive letter, but at this instant I don't have a vacant drive to try it on.


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#5 Dirkk

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Posted 05 May 2015 - 05:33 AM

It works, you can assign those letters on Win 7 as well, but, I meant, may be there will occur problems at some time later one do not know at the moment.


Edited by Dirkk, 05 May 2015 - 05:38 AM.

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#6 Platypus

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Posted 05 May 2015 - 05:53 AM

It's not something I've tried myself, but if it is only used for removable storage drives, I doubt if there's much likelihood of striking a problem. I guess it's possible a program might find it confusing, but I don't know of any way to predict.

 

The last thing I used a floppy disc for was several years ago on an older mainboard to do a BIOS update. Even if for some strange reason it was later necessary to use a USB FDD for some purpose, I think you just wouldn't be able to use it at the same time as a USB HDD was already connected as drive A:. Otherwise I don't expect there should be a clash, since it's normal for a drive letter to be dynamically allocated to different removable drives as they're added and removed from the system.


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#7 Dirkk

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Posted 05 May 2015 - 06:07 AM

Algright, so I will just try it in everyday life. Like you say, I also assume it seems to be most unlikely that a bad thing will happen using those letters or else it will be enough to just assign another ("normal", common) letter.

 

Many thanks.


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#8 coxchris

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Posted 05 May 2015 - 03:53 PM

Floppy devices are not in use today but are consider as "Legacy Devices" Although Tape drives are still use as server backup


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#9 Dirkk

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Posted 05 May 2015 - 04:54 PM

Thank you, coxchris,

 

OK, but why obviously are the drive letters A: and B: used / reserved for those floppies (or whatever) nowadays?

 

And why not back up on a hard disk instead of using a tape which seems to have drawbacks compared to a hdd?


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#10 mjd420nova

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Posted 05 May 2015 - 08:12 PM

The origination of the A:  and B: goes back to the original IBM PC and their BIOS.  The devices were numbered in order of BIOS  POST.  #1 for CPU #2 for memory #3 for keyboard  #4 for parellel port devices  #5 for boot device A: or B: #6 for serial devices #7  and an ever changing list of expanded list for hard drives, expansion ports and all manner of interface cards for dedicated devices like video and sound cards. 



#11 coxchris

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Posted 05 May 2015 - 11:38 PM

Tape drives store more data then a standard hard drive they can store up to 10+ TB  tapes can be inexpesives to companies. Its a mixture of Raids/Harddrives/Tape drives. http://en.wikipedia.org/wiki/Tape_drive


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#12 Dirkk

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Posted 06 May 2015 - 01:40 AM

The origination of the A:  and B: goes back to the original IBM PC and their BIOS.  The devices were numbered in order of BIOS  POST.  #1 for CPU #2 for memory #3 for keyboard  #4 for parellel port devices  #5 for boot device A: or B: #6 for serial devices #7  and an ever changing list of expanded list for hard drives, expansion ports and all manner of interface cards for dedicated devices like video and sound cards.

 

 

OK, and obviously some remainings - e.g. the use of A:, B: -  of the origination are still alive. Very strange. But at the moment as I am trying since yesterday the use of those letters I cannot see any difference, it appears to work flawlessly, besides of FreeCommander does not show the free size of A:.

 

 

Tape drives store more data then a standard hard drive they can store up to 10+ TB  tapes can be inexpesives to companies. Its a mixture of Raids/Harddrives/Tape drives. http://en.wikipedia.org/wiki/Tape_drive

 

Thank you for the link. Yes, a big capacity. Those vintage tapes look quite...old. And I guess they are cheaper than hard disks.


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#13 coxchris

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Posted 06 May 2015 - 10:22 PM

Legacy computers might have two floppy drives so A: can be Primary floppy  controller and B: secondary floppy controller 

 

Once upon a time, the early CP/M and IBM PC style computers had no hard drive. You had one floppy drive, and that was it. Unless you spent another $1k or so on a second floppy drive, then your system was smokin'! If you only had one drive it was common to boot from one disk, put in the other disk with your programs and data, then run the program. Once the program finished, the computer would request that you reinsert the boot disk so you could use the command line again. Copying data from one disk to the other was a series of

Please insert source disk into drive A:...
Please insert destination disk into drive A:...
Please insert source disk into drive A:...

By the time hard drives became cheap, the "expensive" computers typically had two floppy drives(one to boot and run common programs, one to save data and run specific programs). And so it was common for the motherboard hardware to support two floppy drives at fixed system addresses. Since it was built into the hardware, it was thought that building the same requirement into the OS was acceptable, and any hard drives added to the machine would start with disk C: and so forth.

During the transition from 5.25" disks (which were actually, physically floppy) to 3.5" disks (which were encased in a harder plastic shell) it was common to have both drives in one system, and again it was supported on the motherboard with hardware, and in the OS at fixed addresses. As very few systems ran out of drive letters, it was not thought to be important to consider making those drives re-assignable in the OS until much later when drives were abstracted along with addresses due to the plug'n'play standard.

A lot of software was developed since that time, and unfortunately much of it expected to see long-term storage on the C: drive. This includes the BIOS software that boots the computer. You can still attach two floppy drives, boot into DOS 6.1, and use it as you would have in the early 90's, with floppy drives A: and B:.

So largely the reason for starting the hard drive at C is for backwards compatibility. While the OS has abstracted data storage to some degree, it still treats A: and B: differently, in such a way that allows them to be removed from the system without altering the OS, caching them differently, and due to early viruses treating their boot sector with more caution than the hard drive's boot sector.

For Windows specifically, it's worth mentioning that you can use A: and B: as the names for volumes, be it a flash drive or an internal hard drive

Quoted from http://superuser.com/questions/231273/what-are-the-windows-a-and-b-drives-used-for


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#14 Dirkk

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Posted 07 May 2015 - 05:03 AM

Alright, many thanks for this, coxchris,

 

So summarized it sounds as if there might be a remaining risk that using A: and B: compared to the use of the other letters might cause something (un)forseen (because of coming from the Dark Ages...well, some time after), may be some program will behave Dark Aged or so and suddenly....

 

Saying boot, if once I had to boot the system from a USB Sick, Multi Media Card, external drive, whatever and A: and B: are already used the way I do now / want it, might that cause problems? May be the sytem will not be bootable that way anymore?

 

Until now I do not have encountered any problem by using A:.

 

Many thanks again.


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#15 mjd420nova

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Posted 07 May 2015 - 10:39 AM

One drive.  That sure brings back memories of using a tape drive similar to an eight track transport.  Boot tapes were 15 or 25 foot, system tapes were 50 to100 foot and programs were as long as 100 foot.  We also had a huge (as big as a dishwasher) hard drive unit that had a 5 MB fixed disk and a 5 MB removable platter.  It was hard to fathom any system that took more than 10 MB to load.






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