Introduction to the basic concept and classification of memory (3)

Source:   Editor: Jessie Update Time :2019-03-12

A digital camera memory can be either a card or a floppy disk, and either active or fixed for saving images.


CF card short for compact flash card is a pocket card inserted in digital camera like a PC card. It can be considered as the adapter (also known as adapter card) to match with standard PC card reader or other PC card devices. Part of CF card structure is made of reinforced glass and metal shell. The CF card uses standard ata/ide interface equipped with a special pcm-cia adapter so that laptop users can use it directly by the pcmcia slot, transferring data easily between digital camera and computer.

SM flash card is smart media card, a storage medium. SM card uses ssfdg/flash memory card, with the characteristics of ultra-small, ultra-thin and ultra-light. Its volume is 37 (length) x 45 (width) x 0.76 (thickness) mm, and its weight is 1.8g. In addition, it is easy to upgrade with low power consumption. Similarly, SM card also has pcmcia interface, convenient for users to transmit data.

Memory stick duo is a miniature memory stick whose volume and weight are about one third of ordinary memory stick. At present, the maximum storage capacity can reach 128mb.

SD card means Secure Digital card, with volume of 32 x 24 x 2.11. It’s fast and very compact, same as MMC in appearance. The majority of digital cameras on the market use these types of memory cards, the first of market share.

XD card, also known as XD-Picture card jointly launched by Fuji film and OLYMPUS, is small in size, fast in transmission, but very expensive in price.

MMC card short for MultiMedia Card has the same appearance as SD card, and both of them are common in many cases.

Micro-hard disk is a relatively high-end storage product. At present, both IBM (Hitachi) and Chinese South Huiton have launched their own micro-hard disk products. Micro-hard disk is exactly the same as CF card in appearance, using the same type of interface.

Yoka is a digital camera storage medium produced by Lexar, same as CF card in appearance. It can be used in digital cameras, pda, MP3 and other digital devices that use CF card. In addition, it is also used as mobile memory which can be directly connected with computer system through USB interface.

Digital film is a digital camera storage medium produced by Lexar. It belongs to the same kind of digital storage media as Hitachi SM card, Panasonic SD card and Sony memory stick.

PC card converter is a kind of connector, into which you can insert CF card or SM card, and then, as a whole, all of them can be thought as a pcmica interface for PC card in computer. This is a general extended interface commonly used in portable computers, and can be connected to pcmica memory card, pcmica hard disk, pcmica modem and so on.

Skills of selecting memory types in embedded applications

The type of memory will determine the operation and performance of the whole embedded system, so the choice of memory is a very important decision. Whether the system is battery-powered or municipal-powered, application requirements will determine the type of memory (volatile or non-volatile) and the purpose of use (store code, data or both). In addition, the size and cost of memory are also important factors to be considered in the selection process. For smaller systems, the memory provided by microcontrollers may meet the system requirements. But larger systems may require additional external memory. When choosing memory type for embedded system, some design parameters need to be considered, including the microcontroller, voltage range, battery life, read-write speed, memory size, memory characteristics, erase/write durability and total system cost.

 

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