# facts | Why is the letter “C” the default main in the hard drives of many computers?

Almost from the moment the hard drives settled in personal computers based on popular operating systems (MS-DOS and Windows, to be more precise) on an ongoing basis, the main partition of these drives has always been marked with the letter “C”. Never wondered why?

The idea of ​​dividing a physical hard disk into logical subsections (or volumes) is usually associated with operating systems of virtual computers developed by IBM in the 1960s, starting with such systems as CP-40 and CP / CMS and subsequently other operating systems of Digital Research, which essentially copied the workings of the CP / M operating system, written by Gary Kildall in 1973. In the earliest systems (CP / CMS), letter letters were most often used to separate physical disks into logical volumes, but later (in such systems as CP / M), letters were already used to identify a specific physical medium.

Since 1980, IBM began to use the relatively popular CP / M operating system in their IBM Personal Computer. From that moment on, bright legal disputes broke out between IBM and Digital Research, the real reasons for which remain unclear until now. According to rumors, disputes between these two companies began from the moment Dorothy Kildall, wife of Gary Kildall (the creator of CP / M) refused to sign a confidentiality agreement at the time of the start of negotiations on this issue. According to sources, at that moment she told IBM representatives that she could not sign such an agreement in the absence of her husband, who had left at that time from the city for a business trip. Some say that this refusal seemed very unusual, because Gary had instructed his wife to conduct such negotiations in his absence.

As the story says, the refusal to sign a confidentiality agreement (which was very disappointed by IBM representatives) was advised to his wife Kildall by Jerry Davis, a lawyer at Digital Research. What happened after that is unknown. Later, Gary Kildall stated that after his return from a small business trip, he and his wife were able to resolve all issues and reach an oral agreement with Jack Sams, a representative of IBM, whom they met on the plane when they flew to rest. Sams himself says that in fact there was nothing of the kind.

Anyway, it is known for certain that after all these delays IBM decided to stop using the relatively popular CP / M operating system in their computers and turned towards Microsoft, which offered licensing for using the 86-DOS operating system purchased from the company. Seattle Computer Products, which is essentially a clone of CP / M. After that, they adapted 86-DOS for new IBM computers, making a few minor changes. The new operating system was called MS-DOS, although many called PC DOS from IBM.

Built on the basis of a clone of the operating system CP / M, MS-DOS, among other things, borrowed from CP / M a scheme for marking letters on hard disk partitions. Thanks to copying many of the elements used in the CP / M operating system, many popular software packages that worked with CP / M could be relatively easily ported to MS-DOS and used on new IBM PCs.

But back to the specific pattern of letter marking hard drives. To a large extent, due to high price requirements, internal hard drives were most often not used in early computers (although HDDs have been used since the 1950s). Instead, they proposed the use of special drives for floppy disks, which worked with 5¼-inch floppy disks and were designated in MS-DOS and some other OS volumes with the letter "A". Some operating systems were supplied with two such drives, therefore, according to the logic of things and according to the English alphabet, the letter “B” was attributed to them. After some time, the replacement of 5-inch floppy disks came 3.5-inch, but the names of the drives with the letters “A” and “B” were already firmly established.

Later in the 1980s, the standard of most personal computers on the market was the presence of a permanent hard drive, but since the first two letters of the alphabet were already used to designate drives for working with floppy disks, the logical solution was to use the third letter of the alphabet, that is, "C" . As a rule, now this section is used in computers as the main one and usually it is here that the operating system and all related programs are installed for work.

Now drives for floppy disks are practically not used. They can be found only in very old, preserved or relatively recently obsolete personal computers, or in systems of very nostalgic fans. However, even in this case, the labeling scheme for floppy drives remains most often of the same type and, as a rule, still implies the use of the letters “A” and “B”. However, the user, with administrative rights, no one forbids to change or add new sections (both physical and logical).

Bonus Facts:

• A remarkable fact is that in UNIX-like systems (and similar ones, like Linux-like ones), the drive letter most often is not used. Here, rather, a single hierarchical system is used, in which every element of the system, be it a file, or a hard disk, or any other computer device, is mounted in the root directory of the file system;
• In MS-DOS, the letter "C" was not always used by default for marking the main logical drive in each system. For example, in the Apricot PC, released in 1983, the letters “A” and “B” were reserved by the system for marking hard disks, and “C” and “D” - for drives for working with floppy disks;
• As of March 2015, Bill Gates occupies the first line of the billionaires of the Forbes list with a total fortune of 79.2 billion dollars. His former Microsoft partner Paul Allen is at 51 of the billionaires and boasts a fortune of 17.4 billion dollars. Steve Ballmer, who joined the company in 1980 as an ordinary employee and became the largest owner of Microsoft shares in 2014, settled between them in 35th place on the list with $ 21.5 billion. Despite the fact that Bill Gates has been at the top of the Forbes list since 2013 and is not inferior to anyone, he donated about $ 28 billion to the Gates Foundation (which he himself leads with his wife Melinda Gates). Its capital is estimated at 32.9 billion dollars. Thanks to this money, vaccines for children are being developed, schoolchildren are being assisted, malaria and polio vaccines are being developed, and much more. The endowment fund of the Gates Foundation is $ 43.5 billion, among which $ 15 billion was donated by Warren Buffet, who is now third in the world’s richest people.

The article is based on materials https://hi-news.ru/computers/fakty-pochemu-litera-c-yavlyaetsya-po-umolchaniyu-osnovnoj-v-zhestkix-diskax-mnogix-kompyuterov.html.