How does a memory card work? Did something change the memory card that stored the information?

Hard disk (flash chip) ——

The hard disk is to use magnetic materials to record information, the magnetic material on the disk is magnetized to represent 1, and the magnetic material is not magnetized to indicate 0, because the magnetism will not be lost after the power is off, so the disk can still save data after the power is off. The storage form of memory is different, and the memory is not made of magnetic materials, but with RAM chips. Now please draw a "field" on a piece of paper, that is, draw a square and divide it into four equal parts, the word "field" is a memory, so that the four spaces in the "field" are the storage space of the memory, this storage space is very small, can only store electrons.

Look at the U flash drive, ***, their memory chip is a flash chip, which works similarly but differently than a RAM chip. Now you draw another "Tian" character on the paper, this time drawing a circle at the top of each of the four spaces, and this circle represents not an electron, but a substance. Okay, the flash chip is powered on, and this time it is also saving the data of "1010".

The electrons enter the first space of the "field", which is the storage space of the chip. Electrons change the properties of the matter inside, and to indicate that the substance has changed its properties, you can color the first circle in the field. Since the second digit of the data "1010" is 0, there is no electron in the second space of the flash chip, and naturally the substance in it will not change.

The third digit is 1, so the third space of "Tian" is energized, and the fourth is not. Now when you draw the word "Tian", the substance in the first space is colored, which means that the substance has changed its nature, which means 1, and the second one is not colored, which means 0, and so on. When the flash chip is powered off, the properties of the substance will not change unless you erase it with power.

When the flash chip is powered on to view the stored information, the electrons will enter the storage space and then feedback the information, and the computer will know whether the substances in the chip have changed. That's it, the data will be lost after the RAM chip is powered off, the data will not be lost after the flash chip is powered off, and the virtual information is not clear for the time being - but I feel that the information is generally virtual, but in a broad sense, information refers to the data, materials, etc. expressed by language and text symbols, it is a kind of consciousness, not a molecule. When you talk about quality, you should mean the quality of the information carrier, so the information itself should not have quality.

The final interpretation right belongs to me).

A memory card is a thing that is used to store data, and it has many uses. Mostly used in mobile phones.

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.

Memory cards belong to the flash type of flash type of products.

Flash memory, on the other hand, uses a single transistor as a binary signal memory unit, and its structure is very similar to that of ordinary semiconductor transistors, except that the transistors of flash memory add "floating gate" and "control gate". The floating gate is used to store electrons, and the surface is covered by a layer of silica oxide insulator and coupled to the control gate by capacitance. When the negative electrons are injected into the floating gate under the action of the control gate, the storage state of the NAND single transistor changes from 1 to 0. When the negative electrons are removed from the floating gate, the storage state changes from 0 to 1.

The function of the insulator wrapped on the surface of the floating gate is to "trap" the electrons inside to achieve the purpose of saving data. If you want to write data, you must remove all the negative electrons in the floating gate, so that the target storage area is in the 1 state, and the write action will only occur when the data 0 is encountered, but this process takes a long time, resulting in the write speed of both NAND and NOR flash memory being slower than the speed of data reading.

It's the same as a computer hard drive, but it's solid-state, because the data is recorded in the same format

The basic memory unit of memory is a bit, and the user can access the information of any bit at random. The effective capacity per page is in multiples of 512 bytes. The write operation of the flash memory must be carried out in the blank area, and if the target area already has data, it must be erased before writing, so the erase operation is the basic operation of the flash memory.

Generally, each block contains 32 pages of 512 bytes with a capacity of 16KB; In the case of high-capacity flash memory, 2 KB pages are used, and each block contains 64 pages with a capacity of 128KB. The I-O interface of each NAND flash memory is generally 8, and each data line transmits (512+16) bit information each time, and 8 is (512+16) 8bit, that is, the 512 bytes mentioned above.

The capacity of each page determines the amount of data that can be transferred at one time, so large pages have better performance. As mentioned earlier, high-capacity flash memory (4GB) has increased the capacity of a page, from 512 bytes to 2KB. The increase in page capacity not only makes it easy to increase the capacity, but also allows for 8Gbit flash memory.

to improve transmission performance. The 2KB page capacity is about 20% higher than the 512-byte capacity.

Write performance: The write steps of NAND flash memory are divided into: sending addressing information Sending data to the page register Sending command information Data is written from the register to the page. The command cycle is also a one, which we will merge with the addressing cycle below, but the two parts are not continuous.

K9K1G08U0M needs to write a page: 5 commands, addressing period 50ns+(512+16) 50ns+200 s=. K9K1G08U0M Actual Write Transfer Rate:

512 bytes. K9K4G08U0M needs to write a page: 6 commands, addressing period 50ns+(2k+64) 50ns+300 s=.

K9K4G08U0M Actual Write Rate: 2112 bytes. As a result, using a 2KB page size is more than twice as high as a 512-byte page capacity.