Why Your Drives Start With C Instead of A And B

We sure have drives in our computers and the first drive is always labeled as C. The following drives carry characters like D, E and so on in the alphabetical order.

The question is, why don’t we have drive A and B? So the simple answer is, these drives belong to Floppy disks that don’t exist anymore!

A few of you might have heard about A only because of the fact we (the old people!) used to see these kind of instructions on our display:

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

A: was the first disk drive and then B: in CP/M. Initially there was just A: drive but then IBM had two slots, the other with B: label. The purpose of earlier drive was to boot different software programs and the later was used to run specific programs. Since it was built into the hardware so these two slots had fixed addresses and still if you try to install floppy disk in your system you would see something like this:

Drives - BlogoGist

Here is the picture that shows these 2 drives – check out the horizontal slots in the PC.


Microsoft says:

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

Sometimes this doesn’t work! So beware of the indexing issues. (Tech guys will understand it!)

In the old days, MS-DOS allocated 2 floppy drives universally and placed the hard drive at drive labeled as C:

This might be because of the fact that IBM computers had 2 floppy drives in all their machines so this makes pretty much good sense to have this kind of configurations.

Well, whatever the story is, at least now you know the reason of not having A: and B: drives. Ah – good old days!

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