What is the difference between flash memory, portable hard disk, USB flash drive, and SD card? How m

Flash memory is a general term for U disks, memory cards and other devices, hard disks are large-capacity storage devices, faster than flash memory, larger capacity, but not suitable for use as removable media, if you need to move, it is best to use a hard disk enclosure, otherwise it is easy to break. The price of the USB flash drive is very cheap, and the mobile hard disk is 40g

7200 rpm plus hard disk enclosure 400 yuan (self-installed).

1. The storage medium of the mobile hard slag tray is an inch mechanical hard disk, and the storage medium of the SD card is a semiconductor chip, which is the most essential difference.

2. The mobile hard disk has a large capacity, and the current maximum can achieve the TB level, but it is large in size and bulky to carry, which is suitable for the quiet reading of data and large software or game installation packages.

3. The nature of the SD card is similar to the nature of the USB flash drive, which is currently mostly suitable for mobile phones and camera memory cards, although the size is the smallest, but because the card reader is needed to read the content, it is not recommended to use it to store data.

USB flash drives rely on flash memory chips to store information. The flash memory chip is similar to the memory chip, but the data can still be saved after the power off (the data will disappear automatically after the memory chip is powered off), the flash memory chip is addressed by the control chip after the power off, and a complete U disk includes the memory chip and the control chip.

The mobile hard disk is an inch is a notebook hard disk, the desktop hard disk is an inch, and the principle of the desktop and the notebook hard disk is the same. The disk body of a hard drive is made up of multiple platters that are placed on top of each other in a sealed box. Hard disk platters are magnetic particles attached to the surface of aluminum alloy (glass is also used in new materials).

These magnetic particles are divided into concentric circles called tracks, and on the tracks of each concentric circle there are as if there are countless small magnets of any arrangement, which represent states of 0 and 1, respectively. When these small magnets are subjected to a magnetic force from the head, the direction of their alignment changes. The magnetic force of the head is used to control the direction of a number of small magnets so that each small magnet can be used to store information.

The platter rotates at a very high speed under the drive of the spindle motor, and its speed per minute reaches 3600, 4500, 5400, 7200 or even more, the magnetic head is in contact with the disk when it stops working, but it is in flight when working, and the magnetic head uses the state of the magnetic material on the modified disc to read and write information.

For the user's point of view.

Mobile hard drives are large in size, and the smallest ones should also be fitted with inch-sized hard drives.

Flash memory like USB flash drive or SD card is about the size of a thumb finger.

As for the working principle of it, as AWDYZHOU said, a single flash memory chip currently has a maximum capacity of 32G, and it will be even larger in the future.

1. Characteristics and differences.

Memory cards are the smallest, the slowest and the smallest of the three. It's a card the size of a fingernail; It can usually be placed in a mobile phone or a small speaker; If you want to read it, you need to connect it to the computer through the card reader to read;

USB flash drive, the capacity is centered, the speed is centered, and the size is centered. It is usually used for small file copies, with a capacity of less than 100G.

Portable hard disk, the largest capacity, the fastest speed, and the larger size. Typically used for big data or file backups.

Second, ** comparison.

SD card 4G is about twenty or thirty yuan.

USB flash drive 4G is about 40 yuan.

The appearance of the mobile hard disk 500g 300 yuan.

Memory cards with smaller capacities, the slowest speeds, and the smallest size. It's a card the size of a fingernail; It can usually be placed in a mobile phone or a small speaker; If you want to read it, you need to connect it to the computer through the card reader to read;

USB flash drive, the capacity is centered, the speed is centered, and the size is centered. It is usually used for small file copies, with a capacity of less than 100G.

Portable hard disk, the largest capacity, the fastest speed, and the larger size. Typically used for big data or file backups.

USB disk, large memory, easy to carry.

Memory cards are expansion cards that are used for mobile phones, cameras, etc., to increase the data capacity of the device. Everyone needs it. (Additional card reader required) But data is easy to lose.

USB flash drive belongs to mobile devices, which exists independently, and is used for devices A-B, B-A to transfer small data and backup small data. Due to its small size, it is easy to break and lose. (I accidentally broke 2 of them).

Mobile hard disk belongs to mobile devices, U disk upgrade, there are one or more discs in it, the working principle is different, the data transmission speed is fast, and the data capacity is large. Now there are portable SSDs, which are better and more expensive than mechanical. But solid-state data retention is not as good as mechanical data retention.

Nowadays, some electronic devices basically need additional memory cards, you can buy an extra mobile mechanical hard disk in life, remember to back up the data in the memory card, when the memory card data is lost, stomp your feet.

As far as mobile storage devices are concerned, they are all designed for data storage. But there are different uses:

1. Mobile hard disk is mostly used for business, in order to backup, store a large amount of data and generated, it is characterized by fast speed, large capacity (Yijie has more than 1TB mobile hard disk products), the disadvantage is large area, inconvenient to carry, although there are small mobile hard disks on the market, such as business cards, but usually only 20g or 30g, and the price is more expensive.

2. U disk is more used for personal use, although 16G, 32G U disk has been launched, but the speed is still not up to the speed of traditional hard disk. Excellent chip writes can reach 10ms, and reads can reach 20ms.

3. Memory cards are mostly used in mobile devices, such as digital cameras, flash camcorders, MP4 devices and other devices, but the speed is lower (generally only 2m-3m s), and more SD cards (including SDHC) and TF cards are used.

There is no best, only the most suitable.

The mobile hard disk records data through magnetization with alloy materials, which is characterized by transmitting data blocks, large capacity, but large size, and inconvenient to carry. U disks, flash drives, and memory cards all use storage particles to store data, and the quality of storage particles affects the performance of U disks, flash disks, and memory cards. These memories are characterized by relatively small capacity, slow transfer speed, small size, and easy portability.

The difference is that the length is different, and these three are all flash memory!

1.Memory card: A multi-functional memory card jointly developed by Panasonic, Toshiba, and SanDisk, which has the characteristics of large capacity, high performance, and security.

Disk: Plug and play, no physical drive required, storage capacity far exceeds that of floppy disks, and it is extremely convenient to carry.

Second, the characteristics are different.

1.Memory card: The operating voltage is volt-to-volt, and the write and read current is only 27mA and 23mA, so the power consumption is very low.

Disk: The port is connected to the computer, which is the channel for data input and output; The main control chip enables the computer to recognize the USB flash drive as a mobile disk.