Computer hard disk partition why only c,d, e,f disk? Where are the A and B plates?

Computer hard disk partition why is C disk? Where are the A and B plates? Both A and B are reserved for floppy disk drives and are all 5.25-inch disks.

Open Windows system computer, see the first hard disk partition is C disk, excuse me, A and B disk where?

The so-called hard disk partition number is the disk character, that is, the drive letter, is the Microsoft System computer to drive (Driver) and the name of the way and identifier. For computers in UNIX and Linux systems, there is no notion of a letter.

In the late 70 and early 80, IBM PCs were a high-end symbol, and hard drive prices hampered the popularity of micro-computers. Other manufacturers have introduced a compatible machine without hard drives, and have come into common homes because of their low prices.

The computer was not able to function without a system, and in that era, the DOS system was prevalent, particularly the 86-dos acquired at the beginning of Microsoft's establishment, and MS-DOS, which was then the most popular. In their early years, they began to assign letters to externally inserted 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.

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, PCWorld, 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.