Explaining Windows Drive Letters: C: vs A: & B:

If you've ever wondered why your Windows PC starts drive letters at C: instead of A:, you're not alone. It seems odd, where did A: and B: go? Here's a quick and geeky dive into the reason behind this.

The Origin: Floppy Disk Drives (1980s–1990s)

Back in the early days of personal computing, especially during the MS-DOS era, floppy disks were king. Systems typically had one or two floppy drives, and the drive letters were assigned as follows:

Drive Letter	Device
A:	First floppy drive
B:	Second floppy drive (if any)
C:	First hard disk drive

Since floppy drives were the primary method of booting and installing software, A: and B: were automatically reserved for them.

Why Were A: and B: Reserved?

PCs came with one or two floppy drives.
The operating system (MS-DOS, and later early versions of Windows) would assign:
- A: to the first floppy
- B: to the second floppy
Once hard drives became standard, the next available letter — C: — was assigned to them.

That’s why even today, your Windows system starts at C: — it’s a legacy of the floppy disk era.

What About Modern Systems?

Floppy drives are now obsolete, but Windows continues to use this historical naming scheme.
C: is still used for the main system/boot drive.
A: and B: are rarely used, but they’re not blocked — you can manually assign them to external drives or network locations if you wish.

IN Summary

Question	Answer
Why no A: or B: in Windows?	Reserved for floppy drives (legacy)
Why does Windows start at C:?	C: was the first available letter after A: and B:
Can I use A: or B: today?	Yes, but you need to assign them manually

Fun Fact

Even today, some software and BIOS setups still check for floppy drives — despite them being extinct — just to maintain backward compatibility!

Why Does Windows Start With the C: Drive? What Happened to A: and B:?