The MS memory stick is a memory card product launched by Sony in 1999. It looks like chewing gum, is the same length as a normal AA battery, and weighs only 4 grams. Adopt 10 pin interface structure, and built-in write protection switch. Depending on the color of the case, the memory stick can also be blue or white. White stripe memory sticks add MagicGate copyright protection and are often used in media players. As Sony's digital product line is very rich, Memory Stick is very popular. Memory Stick has been widely used in digital cameras, PDAs and digital camcorders. The Secure Digital card, or SD card for short, literally means a Secure card, and it offers better security than the CF card and the earlier SM card. Matsushita, Toshiba and SanDisk jointly developed a new memory card product, the biggest feature is through the encryption function, to ensure the security of data confidentiality. SD cards can be seen as MMC upgrades in many ways. Both look and work the same, with the exception of the slightly thinner MMC card, which can be used by any machine using an SD card device. Its overall dimension is 32mm×24mm×2.1mm. SD card memory card, is used for mobile phones, digital cameras, portable computers, MP3 and other digital products on the independent storage medium, generally in the form of cards, so collectively referred to as "memory card", also known as "digital memory card", "digital memory card", "memory card" and so on. Due to the large size of traditional CF cards, Infineon and SanDisk launched a new memory Card product called MultiMedia Card (MMC) in 1997. The dimensions of the MMC card are 32mm x 24mm x 1.4mm. The MMC card uses a 7-pin interface and does not have a read/write protection switch. Mainly used in digital camera, mobile phone (such as Siemens MP3, mobile phone 6688), and some PDA products. Flash Card [6] is a Memory that uses Flash Memory technology to store electronic information. It is generally used as a storage medium in digital cameras, handheld computers, MP3 and other small digital products, so it is small and like a Card, so it is called Flash Card. Pci-e flash memory card (PCI-Express) is the latest bus and interface standard, its original name is "3GIO", PCIe belongs to the high-speed serial point-to-point dual channel high bandwidth transmission, the connected device allocates exclusive channel bandwidth, does not share resources, mainly supports active power management, error reporting, end-to-end reliability transmission, [7] Such functions as hot swap and quality of service (QOS).