Why can USB flash drives and memory cards store a large amount of information, and what is the princ

The memory card is regarded as a mesh structure, that is, a matrix structure, which is called a flash storage matrix, which is composed of small storage units in the grid, relying on the memory chip flash, which stores binary information, and the specific situation can refer to the following content.

1. The memory card relies on the flash chip to store information, and its storage principle should start from EPROM and EEPROM, EPROM means that the content can be erased by special means and then re-written. Its basic unit circuit often adopts a floating gate avalanche injection MOS circuit, which is referred to as FAMOS. It is similar to the MOS circuit in that two highly concentrated p-type regions are grown on an N-type substrate, and the source S and drain D are elicited by the ohmic contact.

2. Secondly, there is a polysilicon gate floating in the SiO2 insulation layer between the source and the drain, and there is no direct electrical connection with the surrounding area. This kind of circuit is represented by whether the floating gate is charged or not, and after the floating gate is charged (such as a negative charge), just below it, a positive conductive channel is induced between the source and the drain, so that the MOS tube is conducted, that is, it is deposited to 0. If the floating gate is not charged, the conductive channel is not formed, and the MOS tube is not conducted, that is, it is deposited in 1.

3. In addition, the EEPROM basic memory unit circuit is similar to EPROM, it is to generate a floating gate on top of the floating gate of the EPROM basic unit circuit, the former is called the first-stage floating grid, and the latter is called the second-stage floating grid. An electrode can be drawn out for the second stage floating gate, so that the second stage floating gate can be connected to a certain voltage VG. If VG is a positive voltage, a tunneling effect occurs between the first floating gate and the drain, so that electrons are injected into the first floating gate, that is, programmed and written.

If the VG is negative, the electrons of the first stage floating gate will be lost, that is, erased, and can be rewritten after erasure.

4. SD card memory card is an independent storage medium used in mobile phones, digital cameras, portable computers, *** and other digital products, generally in the form of cards, so it is collectively referred to as "memory card". Memory cards have the advantages of small size, easy to carry, and simple to use. At the same time, since most memory cards have good compatibility, it is easy to exchange data between different digital products.

In recent years, with the continuous development of digital products, the storage capacity of memory cards has been continuously improved, and the application has also become rapidly popular.

What is the storage principle of a USB flash drive? How does flash memory store data?

To be precise, it is the number of reads and writes per sector.

Intel gives the claim that MLC's SSD hard drive writes 129TB of data per day and can be used continuously for 20 years.

I can't remember a little, but it's too expensive) general SLC

SSDs don't meet this requirement. The chip of the USB flash drive and the SSD cannot be compared with the specific number of reads and writes.

Officials generally do not give accurate data.

A Kingston merchant in Computer City told me.

The longevity of the USB flash drive has a lot to do with the scheme he uses.

If all the same chips in order to achieve faster speeds.

A different approach had to be taken.

Each faster solution is to sacrifice not necessarily the number of reads and writes.

The regular number of times is 2W-3W times) The memory card is about the same as the USB flash drive. HDD I just said SSD

If it's a traditional hard drive, I really don't know about this, it should be much higher than the previous 2 products.

I've read a lot, and most of them talk about performance, and no one talks about the principle. I only know that hard disks store data through the presence or absence of magnetism, just like the reading and writing of the gramophone in the past, all of which require magnetic tracks, but the material has changed and the volume is smaller.

I haven't understood the data principle of memory cards and USB flash drives.