The computer only has C disk? No, there's A and B.

When we open the Windows system computer, we see the first hard disk partition must be C disk, then, since it is C disk, A and B plate where?

We live in the so-called hard disk partition number is actually the letter, that is, the drive letter, the Microsoft system under the computer to drive (Driver) and the name of the way and identifier. In the case of UNIX and Linux systems, there is no concept of the letter.

In the late 70 and early 80, IBM PCs were once a high-end symbol, and hard disk prices hindered the popularity of micro-computers. Based on this situation, other manufacturers have introduced a compatible machine without hard drives, because of low prices and gradually into ordinary people's homes.

The computer did not have a system to play a role, and in that era, the DOS system prevailed, especially in the early days of Microsoft's acquisition of the 86-dos and then the red of MS-dos for the most. In the early years, they started to assign letters to external drives, when the default first letter was actually a disk, corresponding to the main storage device floppy disk of the year.

The early floppy disk was 8 inches large, not conducive to the design and popularization of microcomputers, in the era of MS-DOS, the real micro-computer received is a 5.25-inch floppy disk.

In the direction of Moore's Law, the technology of 5.25-inch floppy disks is maturing and prices are falling, while the system requires more and more drive storage space, so the use of dual-drive micro-computers has become popular.

As a result, both A and B are reserved for floppy disk drives and are all 5.25-inch disks.

5.25-inch and 3-inch floppy disks are:

1982, the Microsoft Panel (MIC) unified 3.5-inch disk industry standards, 3-inch disk began to become the mainstream configuration. The advantage of a 3.5-inch disk is that the capacity is several times larger than the 5.25-inch disk, but smaller in size. With the advent of a 3.5-inch disk, the distribution of the dual floppy drive gradually became 5.25 inches +3.5 inches.

Moore's law also takes effect in the field of hard disk, with the development of hard disk technology and the decrease of price, the hard disk becomes the main storage medium of micro computer gradually.

The first two letters have been occupied by the floppy disk drive, so starting from MS-DOS 5.0, the system forced the primary hard drive primary partition named C disk, the window after the birth of this practice, whether it is the new hard disk partitions or discs, u disk, New drives, such as SD card and mobile hard drive, can only be postponed using the letter after D disk.

Since the 21st century, with the CD drive, USB disk and other Flash media drive development, floppy disk gradually replaced.

In February 2007, PC, Europe's largest computer retail chain, announced that it would stop selling floppy disks and floppy disk drives.

April 2010, was the first in 1981 to launch a 3.5-inch floppy disk, with 70% of the market share of the Japanese Sony Company announced the March 2011 complete production of 3.5-inch floppy disk.

However, the establishment of the letter of the name of the rule has been established since then, in A and b to become a historical noun, C is already the default in Windows computer's first hard disk partition.