At the weekend, I was watching TV at home while my girlfriend was working on her computer, but it didn’t seem to go well, so I had this conversation.
In computers we use, there are two types of media for storing information:
One is internal memory, which loses what it remembers when the power goes off.
One is external memory, which can survive a power outage.
Internal memory, which is commonly referred to as memory, has a high speed of information access, but usually has a small capacity and depends on power supply. The contents stored in memory will be lost after power failure. Internal storage includes registers, Cache and main storage.
Another type of external memory, which does not rely on power, has a larger capacity than memory, but the access speed is slower. Common external storage includes disk, CD, U disk and so on.

The program code and data needed for CPU operations come from memory, and the contents of memory come from disk, so the disk does not directly interact with the CPU.
There are two kinds of disks: floppy disk and hard disk.
Let’s take a look at the floppy disk and the hard disk in the order of their arrival
A floppy disk
In the early days of computers, there were no hard disks, and data storage was mainly on floppy disks.
Floppy Disk is the earliest removable media used in personal computer (PC). Floppy disk reading and writing is done through the floppy disk drive.
Floppy disks were an essential piece of hardware on early computers and were the first removable media used on computers. As a kind of removable storage hardware, it is suitable for some small files that need to be physically moved. The reading and writing of the floppy disk is completed by using the floppy disk drive.
Floppy Disk driver (Floppy Disk driver) is commonly known as “floppy drive”, it is the device that reads the floppy disk.

So on early DOS computers you often saw the following information:
, both Please insertsourcedisk into drive A:... ·Please insert destination disk into drive A: , both Please insertsource disk into drive A:...
Copy the codeIn order for A floppy disk to be read into the computer, it needed to be mapped to some identifier in the computer, so the letter “A” was used as the first drive letter by the floppy disk drive, and then more computers began to be equipped with A second floppy disk drive to meet the needs of data copy, so the drive letter “B” was occupied by the floppy disk drive.
So the floppy drive occupies the positions of drive A and DRIVE B in order: drive A is the 3.5-inch floppy drive and drive B is the 5.25-inch floppy drive.
Later Windows systems also use the DOS partition Settings.

The true meaning of disk A is “the first floppy drive”, not A single 3.5-inch floppy drive or floppy disk. In fact, the earliest floppy disks were 8-inch floppy disks, so the earliest A-disks were 8-inch floppy drives. However, 8 inch floppy disk as A result of carrying inconvenient and other reasons, soon replaced by 5.25 inch floppy disk, later appeared A PC with 2 floppy drive, so there is A disk and B disk distinction, but both are 5.25 inch floppy drive. Later, with the introduction of 3.5-inch floppy disks, 3.5-inch and 5.25-inch floppy disks began to coexist, so there were two floppy disks on the PC, one was A 3.5-inch floppy disk (usually disk A), and the other was A 5.25-inch floppy disk (usually disk B, but also the opposite).
The hard disk
3.5-inch floppy disks had their heyday in the 1980s and 1990s, and as many as 5 billion were in use worldwide in 1996. Until the advent of CD-ROM, USB storage devices, floppy disk sales gradually declined.
Apple’s original iMac in 1998 was the first computer to drop floppy disk drives, and Dell’s Dimension desktop in 2003 ditched floppy disk support. Since then, fewer and fewer new computers have come with floppy drives as standard.
Instead, the hard disk is the main external storage in a computer. A hard disk is one of a computer’s primary storage media. It consists of one or more disks made of aluminum or glass. The disc is covered with ferromagnetic material.

As hard disks were developed, early computers began to think about how to make them compatible. To make them compatible, the first consideration was to partition the hard disks. The stages named A and B are already occupied by floppy disks, so hard disks can only start with C.
And with the development of hard disk technology, on the one hand floppy disk gradually withdrew from the historical stage, on the other hand hard disk began to support multiple partitions, then, evolved into today’s computer we see a number of partitions, starting from C, are RESPECTIVELY C, D, E, etc..

Disk partitioning is essentially formatting the hard disk so that it can be used to store various kinds of information. In a hard disk, a primary partition (active partition) is usually divided first. Generally speaking, this is the PARTITION C. Then the extended partition is created. In the extended partition, several logical partitions are created, such as disks D and E.
As a result, many new Windows computers come with at least one C drive.
Since any hard drive installed in the computer will have drive C by default, the initial installation location of the software can be set to drive C to avoid the absence of this partition.
In fact, when the software is installed, the default selection is the Program Files directory of the system disk (environment variable: %programfiles%), but in most cases, the system disk happens to be C disk.
Another reason is that it is much smoother to install software on drive C.
For mechanical drives, spindles work in CAV (Constant Angular Velocity), so more data is read from the outer ring of the drive than from the inner ring of the drive in the same amount of time.
In other words, data of the same size can be read from the outer ring of the hard disk for a shorter time than it can be read from the inner ring.
According to the normal partition method, set C is located on the outer ring of the new hard disk, and D, E and F behind set C gradually move inward. Therefore, C disk read speed will be relatively faster.
Of course, this applies only to mechanical hard drives, not to solid-state drives, which are so common today, so if you’re using SSDS, feel free.

There are many reasons that affect the speed of a system, and hardware has two important parts: CPU (processor) and memory. The CPU, needless to say, is the brain, processing all the calculations; Memory is where you run your program.
In the past, the configuration of computers is generally not too high, CPU calculation efficiency is low, fast operation is difficult, especially the memory space is also tight. But Windows has a way of using virtual memory based on memory availability. Drive C is exactly where the virtual memory is. If drive C is full, there is no room for virtual memory. Memory brothers can only rely on their own small body hard resistance, when running multiple programs, it is easy to cause the computer to slow down or even crash.
In fact, this is just a relic of history. Today’s computers are hardware powerful enough and have enough space to allocate virtual memory properly.
