Good lord, this makes me feel old.
Of course A: and B: drives are a MS-DOS/Windows thing. The first OS I ever used didn’t have that concept, but instead on the TRS-80 the drive numbers were appended after the file name, like MYFILE.TXT:1 or whatever.
I actually prefer the Linux way anyway of mounting drives or volumes in directories. Most people don’t know this, but you can also do this on Windows now. Though I don’t recommend it as it confuses the hell out of Windows users and even Windows sysadmins.