Where are the drive letters a and b?

Computer operating systems assign letters to a different drive to help both user and other programs identify the path for a file. When you add a new storage device on the computer automatically it is assigned the next letter after the last one.

Disk drives A and B in the Windows operating system computer are reserved for a floppy disk that was the original booting drive. Drive A used to hold booting files while B used to hold user or program files.

Where are drives A and B?

The 2 drive letters A and B are reserved for floppy disks which were old computer booting drives for backward compatibility. When computing technology was still young floppy disks were the best random access types of storage media around. Computers were designed to read data from the floppy disk as the main drive. When operating system developers came they designed the software to conform with what the computer manufacturer does.

When computer storage is advanced to CD and hard disk that can hold more data they retain the floppy as the main booting drive for backward compatibility. This enabled the user to use both the old computer floppy disk to boot or choose to use CD or hard disk for new models.

So when companies stopped using floppy to use the operating system still retain drive letters A and B to be used for floppy diskette.

Can you assign letters A and B to other drives?

Yes, you can assign the letters A and B to another drive on a Windows computer although it is not recommended. For compatibility issues, you should leave it to be. Again you still have other letters from D to Z to assign you other drives.

To change the drive letter to A or B in Windows use the disk management utility on the Windows setting.

The image above shows the DVD drive assigned letter A. Please note that you shouldn’t do this even if it is possible since it may bring problems when reading data from the drive.

How to assign a letter to drive on the Windows operating system

In the modern computer by default the drive that the operating system files is assigned the letter C which cannot be changed since it will create an error when reading files. The second logical partition on the same drive will be assigned the letter D. 

Optical disk CD or DVD drive is assigned the letter E. All other additional drives will take the next letter but you can assign them any other letter that is left. Still, note that by default letters A and B are reserved for legacy floppy booting.

To assign a letter on Windows open the control panel > Administrative Tools > Computer Management > Storage > Disk Management. You will be presented with a window similar to the one below which has all installed and detected disks.

To change the letter right click on the preferred drive and choose “Change drive letter and path”. To assign a letter select from the available letters. Those letters that are already assigned will not be on the list. When you click OK the system will give a warning message that changing the letter and path may affect file access. If comfortable you can click YES and the drive letter will be changed.

Why are disk drives assigned letters?

Disks are assigned letters to have a clear directory and file path that is used to identify their location. When the operating system is installed it is assigned the letter C which directs the computer to access all files related to Windows from that drive.

If you change a drive letter that has a program file installed on it again it will give a file path not found error and you may need to reinstall those programs. So it is recommended to leave the letter assignment to be automatic unless it is necessary. The necessity to change mostly comes when you need to assign a drive on the network for many users to share.

The letter assignment also helps the system to have a good file management system which makes it easy to retrieve files and folders.