1. CF card
CF card (Compact
Flash) was first introduced by SanDisk in 1994. CF card has PCMCIA-ATA function and is compatible with it; The weight of CF card is only 14g, which is only the size of a cardboard match (43mm
x 36m
x
m3.3mm). It is a solid product, that is, it has no moving parts when working. CF card adopts flash technology, which is a stable storage solution and does not need batteries to maintain the data stored in it. For the stored data, CF card is more secure and protective than the traditional disk drive. It is 5-1 times more reliable than traditional disk drives and type III PC cards, and the power consumption of CF cards is only 5% of that of small disk drives. The CF card works with a voltage between 3.3V and 5V (including 3.3V or 5V). These excellent conditions make most digital cameras choose CF card as their preferred storage medium.
as a worldwide storage industry standard, CF card ensures the compatibility of CF products and the backward compatibility of CF cards; With the more and more extensive application of CF cards, manufacturers actively improve the technology of CF cards, promote the launch of a new generation of advanced mobile devices with small size, light weight and low energy consumption, and thus improve work efficiency. CFA is headquartered in Palo
Alto, Canada, and its members have the right to get CF cards, CF trademarks and CF technical details free of charge. CFA has more than 12 members including 3COM, Canon, Kodak, Hewlett-Packard, Hitachi, IBM, Panasonic, Motorola, NEC, SanDisk, Seiko (Epson) and Socket
Communications. Moreover, the main digital camera manufacturers have set up a special organization to develop CF products.
CF card has the following disadvantages:
1. Limited capacity. Although the capacity is increasing exponentially, it still can't keep up with the pixel development of digital cameras. At present, products with more than 5 million pixels are the minimum specifications of popular high-end products, and the mainstream market for civilian use has reached 3 million pixels. Under the common JPEG compression format, the capacity is acceptable, but the professional TIFF(RAW) format file still can't hold a few image data.
2, the volume is larger. Compared with other kinds of memory cards, the size of CF card is slightly larger, which also limits the size of digital cameras using CF card, so most of the popular ultra-thin digital cameras now give up CF card and switch to smaller SD card.
3. Performance limitations. The working temperature of CF card is generally -4 degrees Celsius. Therefore, in the environment below degrees, digital cameras can basically be said to have become "waste". Even professional machines are not immune. Although the cold resistance of the current military CF card reaches-4 degrees Celsius, it is still unknown when it will be popularized and when the price will fall to the point where ordinary people can afford it.
at present, the capacity of the largest CF card in the world has reached 64M. Common in the general market are 8MB, 16MB, 32MB, 64MB, 128MB, 256MB, etc. (those above 128MB are Type II).
2, SD card
SD card (Secure Digital Memory
Card) is a new generation of memory equipment based on semiconductor flash memory. The SD card was jointly developed by Panasonic, Toshiba and SanDisk Company in August, 1999. The SD memory card, the size of a stamp, weighs only 2 grams, but it has high memory capacity, fast data transmission rate, great mobile flexibility and good security.
the p>SD card combines SanDisk flash memory card control with MLC (multi-level
cell) technology and Toshiba .16u and .13u NAND technology in a volume of 24mm×32mm×2.1mm It is connected with a special driver through a 9-pin interface, and no extra power is needed to keep the information memorized on it. Moreover, it is an integrated solid medium without any moving parts, so there is no need to worry about the damage of mechanical movement.
the structure of SD card can ensure the security of digital file transmission, and it is also easy to reformat, so it has a wide range of applications, and multimedia files such as music, movies and news can be conveniently saved in SD card. Therefore, many digital cameras have begun to support SD cards.