C:\> a:
A:\> b:
Invalid drive specification
A:\>
Most of us who use computers nowadays are familiar with the drive lettering system. The hard disk which stores the operating system and main applications is the C: drive and, in most systems, the hard disk which stores the data is the D: drive. The CD-ROM (or DVD for those more high-tech systems) is known as the E: drive (or basically the next letter after the last hard disk drive. USB thumbdrives, flash memory sticks when inserted take on yet another designation, probably the F: or G: drive depening on what else is already in the system.
In networks, a user’s ‘networks space’ is designated the H: drive and now, the network drive letters run all the way through to Z:; each one has its own purpose which for all intents and purposes, as lay users we do not need to know.
One wonders, why does it all start with the C: drive? Why not A: or B:? One must look to the early days of computing for the answer…
In the good old days, when the (510KB?) 5 ¼” floppy was being used (the high density one was the 1.2MB, the 720KB/1.44MB 3 ½” floppy was still unheard of, much less the Zip drives which by themselves are nearing their demise)… hard disk drives were still quite rare. By the way, instead of the immense 20GB hard disks we have nowadays, hard disk sizes back then were still in the range of 100 – 200MB. Most computers had two floppy disk drives, one for the OS (MS-DOS, DR-DOS or PC-DOS in those days. No Windows yet, that invention came with Windows 3.0, followed by Windows 3.1 which still depended on MS-DOS up to 6.22, which was superseded by Windows 95 in 1996?) One would insert the boot up disk into one of the floppy drives and of course, the other floppy drive was required for data, which in those days was WordPerfect for documents, Lotus 1-2-3 for spreadsheets and dBase for databases, and printouts were from dot matrix printers. Colourful printouts from inkjet printers were unheard of. RAM of 4MB was considered luxurious. Back then CPU speeds were the 8086 (XT), 80286, 80386, 80486 (which included the 486-SX and 486-DX), then the Pentium which superseded the 80x86 classification, and as we all know now, Pentium Pro, Pentium II, Pentium MMX, Pentium III, Pentium 4 and after that a range of processor chips by Intel's competitors.
Anyway, as you guessed, the boot up disk drive was the A: drive and the other floppy drive was the B: drive. When hard disks became commonplace and the OS started to be installed on the hard disk, computers started to ship with only one floppy drive. By then, the 3 ½” floppy began to supersede the 5 ¼” floppy. For a while, computers had one of each floppy drive for compatibility reasons. However, after a while the 5 ¼” drive was phased out totally. There would only be one floppy drive, the 3 ½” floppy which was designated the A: drive. If you are kiasu, you have two. Anyway, by the early 2000s the floppy drives started to be superseded by Zip drives and then, thumbdrives, Flash drives and what have you. As of this writing, the laptop I am using has a removable 3 ½” floppy drive which has not seen any use recently. Most of the data which I used to keep on diskettes have been transferred to my thumbdrive, and the diskettes trashed.
Nowadays, new computers do not even ship with a floppy drive, meaning simply that the use of the designations A: and B: is moribund.
I wonder whether there will be any new convention to eventually reassign the letters A: and B: to some other drive, once the older generation which used floppy disks retire and pass on. Only time will tell. By then, probably the convention of using C: for the main OS disk will have stuck for so long that people will still continue to use it. Perhaps there will come a time when the ‘legend of the lost A: and B: drive’ abounds… but by then, perhaps hard disks, and even computers themselves are already superseded by some nanotechnological device.
Remember cassette tapes? Already been superseded by CDs, themselves superseded by MP3 players. I wonder what nanotechnological device will the technologists of the future use. One that combines the function of a laptop, MP3 player, phone, portable hard disk (a souped up, much less problematic version of the iPhone, most importantly Not dependant on a computer to sync with). And this device will be no bigger than a phonecard, can just fit in a wallet. Just half a century ago, with the big mainframe computers which filled a whole room, laptop computers were a dream. Even the tall servers the size of a cupboard were referred to as ‘minicomputers’, and desktop computers ‘microcomputers’.