Why are the first hard drive and system partitions in Windows traditionally assigned the letter C:? Why weren't drives assigned starting with A: and B:, and why has that convention continued even though floppy disks are rarely used anymore?
3 Answers
A: and B: were traditionally reserved for floppy disk drives. Early PCs often had one or two floppy drives and no hard drive at all, so the first hard drive was assigned C:. Windows kept this convention for compatibility with older software and setup routines.
It’s not a strict technical requirement. You can sometimes assign a different letter to a volume, including A: or B:, through operating-system disk-management tools. However, the main Windows installation is normally kept as C: because many programs and system components expect that traditional layout.
The convention goes back even further than early Windows. MS-DOS inherited drive-letter behavior from CP/M-era systems, where A: and B: represented floppy drives. By the time hard drives became common, C: was already the expected system-drive letter.
Changing it would break assumptions built into a huge amount of software, scripts, documentation, and troubleshooting knowledge. There’s little practical benefit to changing the default today.
That makes sense for older machines, but why not change it now that floppy drives are mostly obsolete?