There are many types of flash memory, including AND, NAND, NOR, DiNOR, and so on, among which NAND and NOR are the most common types at present. NOR-type flash memory is the most common type of flash memory that we come across nowadays, which is similar to the commonly used memory in terms of storage format and read/write method, supports random read/write, and has a higher speed, which also makes it It is very suitable for storing programs and related data, and cell phones are where it is used. However, the biggest drawback of NOR-type is the small capacity, Intel has only recently released a 64Mb chip produced using a 0.13μm process. Compared with NOR type, NAND type flash memory has the advantage of large capacity, in the last year 512Mb chip is not uncommon. However, NAND type is slower because it has only 8 I/O ports, much less than NOR type. The 8 ports need to complete the address and data transfer will have to let these signals take turns to transmit, obviously, this time serial transmission is much slower than the parallel transmission of NOR-type, memory and other chips. However, NAND-type storage and transmission is based on page and block units (a page contains a number of bytes, a number of pages to form a block), relatively suitable for continuous transmission of large data, which can also partially compensate for the disadvantages of serial transmission. Therefore, the most suitable job for NAND-type flash memory is to save large-capacity data and to be used as an electronic hard disk, a mobile storage medium, and so on.
In order to be used in a variety of devices, flash memory must be connected to the device through a variety of interfaces: the most commonly used interfaces for connecting to computers are USB, PCMCIA, etc.; for connecting to digital devices, there are special interfaces and specifications for the form factor, such as CF, SM, MMC, SD, Memory Stick, etc., of which the most widely used and the ones with strong expansion capabilities are CF and Memory Stick.
This is why NAND type flash memory is most suitable for the job of saving high-capacity data as an electronic hard disk and as a mobile storage medium.
Portable storage (USB Flash Disk), also known as flash disk. It is a portable memory with USB interface and Flash Memory technology that is easy to carry and has a beautiful and fashionable appearance. Flash Disk is Flash Memory as a medium, so it has the advantages of multiple erasable, fast speed and anti-magnetic, shockproof, moisture-proof. Flash disk generally includes flash memory (Flash Memory), control chip and shell. Flash drive using the popular USB interface, the volume is only the size of a thumb, weighing about 20 grams, no drive, no external power supply, plug and play, to achieve the exchange of files between different computers, storage capacity from 16MB ~ 2GB ranging to meet different needs. Flash disk products are through the integration of flash memory chips, USB I / O control chip into the product, its product characteristics are mostly similar, only the shell design, bundled software and additional features on the difference. There are many types of additional features on flash drives, such as data encryption, system boot functions, built-in e-mail and chat tools, and more
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