How Do I Choose the Best Cheap SD Cards?

Mobile phone memory card, different brands of mobile phone manufacturers in the production of mobile phones with different processes, hardware facilities are also very different, such as mobile phone memory card slot size specifications are different. And memory card manufacturers have therefore produced different sizes of mobile phone memory cards, The use of mobile phones with different size memory card slots. Name these memory cards (such as TF card, MMC card) to distinguish these different size memory cards.

Phone memory card

Generally speaking, these cards have different sizes and specifications, so there are so many names (the process is slightly different). TF cards, MMC cards, SD cards, etc. are all used as memory cards for mobile phones or digital cameras of different brands. And other digital products.

Chinese name: Phone memory card
Foreign name: Memory card
Big small: Fingernail-like

Use: Store
Features: Low cost and high capacity
On behalf of: SanDisk /

Fingernail-sized memory cards are mainly used in new mobile phones and consumer electronics such as DC and DV. It is a low-cost, high-capacity production process. Can hold files in various formats.

Confirm what type of memory card to buy. The mobile phone manual will indicate which memory cards are supported. Take a look before buying a memory card. If your phone supports more than two types of memory cards, you should choose the one with the fastest and most stable memory card. take

TF card (full name trans flash, also called micro SD card, can be inserted into the SD card converter to use SD card, Motorola mobile phone more commonly used this memory card)

RS-MMC card (also called mobile mmc card, MMC card can be inserted when using MMC card, NOKIA mobile phones are more used)

miniSD card (can also be used as SD card after inserting SD converter)

MS card (also called memory stick, a memory card commonly used by Sony Ericsson mobile phones)

CF card (full name Compact Flash Card, often used in digital cameras)

SD card (full name Secure Digital Memory Card, also used in digital products such as digital cameras / mobile phones)

MMC card (full name MultiMedia Card, also used in digital products such as digital cameras / mobile phones)

M2 card (full name Memory Stick Micro, which is a flash memory card used by Sony digital products. It is only used by Sony and Sony Ericsson products, and is generally not compatible with other brands. MemoryStickMicro is a dual voltage medium that supports both 3.3V and 1.8V Voltage. The size of the MemoryStickDuo is 20 × 31 × 1.6mm (width / length / thickness), its length is only 60 of the standard MemoryStick, the volume is 33, and 21.5 × 50 × 2.8mm (width / length / thickness) ), Weighs 4g (with adapter) / 2g (body weight), compatibility is the same as standard MemoryStick. MemoryStickDuo's working voltage is 2 power is 45mA (working), 130A (standby), the use environment temperature is 0 ~ 60 degrees , Write speed is 1.8MB / sec, read speed is 2.45MB / sec. MemoryStickMicro (M2) memory stick has a breakthrough in storage capacity and volume, its introduction is expected to further promote mobile phone multi-function settings and slim appearance Designed to provide a better mobile phone-based integrated solution. MemoryStickMicro (M2) memory stick is suitable for two voltages: 1.8 volts and 3.3 volts. 1.8 volts is currently commonly used in mobile phones The operating voltage of 3.3V can be matched with other existing MemoryStickPRO compatible products. The converter of this memory stick is the same size as the standard MemoryStickPRO converter, through which data can be exchanged between corresponding products. In line with the multiple trends of mobile phone integrated entertainment functions, large screens, intelligence and control of volume, the storage medium also needs to be slimmer, larger in capacity, and faster in reading and writing. M2 memory cards are not only smaller, but their theoretical maximum capacity is up to 32GB, the theoretical maximum transmission speed is 160Mbps,

Phone memory card unit profile

All information on the network is transmitted in "bit" (bit) units, and a bit represents a 0 or 1.

Every 8 bits constitute a byte. What is byte? An English letter occupies one byte, that is, 8 bits, and a Chinese character occupies two bytes. Generally the bit abbreviation is lowercase "b" and the byte abbreviation is uppercase "B".

Phone memory card unit conversion

Each kilobyte is called 1KB. Note that the "thousand" here is not 1000 in our usual sense, but 1024. That is: 1KB = 1024B. However, if strict calculation is not required, 1K can be considered to be 1000. 4) Each thousand KB is 1MB (also K here refers to 1024), that is: 1MB = 1024KB = 1024 × 1024B = 1,048,576B This is an accurate calculation. If it is not precisely required, you can also consider 1MB = 1,000KB = 1,000,000B

It should also be noted that storage product manufacturers will directly calculate the product's capacity in the calculation method of 1GB = 1000MB, 1MB = 1000KB, 1KB = 1000B. This is the main reason why the capacity of purchased storage devices does not reach the nominal capacity ( (Such as a 320G hard drive is only about 300G)

Every 1024MB is 1GB, that is, 1GB = 1024MB. As for how many bytes are equal, do it yourself. Now we have figured out what people often mean by saying that a floppy disk is 1.44MB, a CD is 650MB, and a hard disk is 120GB. For example, if a novel of 100,000 Chinese characters is stored on disk, how much space will it take? 100,000 Chinese characters = 200,000B = 200,000B ÷ 1024195.3KB195.3KB ÷ 10240.19MB

Mobile memory card unit conversion introduction

With the increase in the amount of stored information, there are now larger units representing storage capacity units, which are higher than gigabytes (GB, gigabyte): terabytes (terabytes), PB (Petabyte) , EB (Exabyte), ZB (Zettabyte), YB (yottabyte), etc., where 1PB = 1024TB, 1EB = 1024PB, 1ZB = 1024EB, 1YB = 1024ZB. So, how big are these units? Please look at the expression: Kilobyte (KB) = 1024B is equivalent to the content of a short story.

Megabyte (MB) = l024KB is equivalent to the text content of a short story.

Gigabyte (GB) = 1024MB is equivalent to the score of Beethoven's Fifth Movement Symphony.

Terabyte (TB) = 1024GB is equivalent to the amount of X-ray picture information in a large hospital.

Petabyte (PB) = 1024TB is equivalent to 50% of the information content in the collections of the National Academic Research Library.

Exabyte (EB) = 1024PB; 5EB is equivalent to the words spoken by humans all over the world so far.

Zettabyte (ZB) = 1024EB is like the total amount of sand on the beaches around the world.

Yottabyte (YB) = 1024ZB is equivalent to the sum of microcells in 7000 humans.

Phone memory card commonly used units

Storage capacity refers to the maximum amount of data that the portable storage product can store, and is the most critical parameter for portable storage products. General portable storage capacity is 16MB, 32 MB, 64 MB, 128 MB, 256 MB, 512 MB, 1GB, 2GB, 4GB, 8GB, 16GB, 32GB, 64GB, 128GB, 256GB, 512GB, of which 16MB, 32MB, 128MB, 512MB, 1GB, 2GB, 4GB storage has been basically eliminated by the market; 8GB ~ 128GB products are the mainstream in the market, the price is within the range acceptable to ordinary users, and it is the capacity type with the most product types introduced by manufacturers; 512GB products are expensive, have fewer user groups, and have fewer product types.

Phone storage card disk storage capacity

As mentioned above, a disk usually uses three levels of addressing. Therefore, the storage capacity of the disk memory can be calculated using the following formula:

Storage capacity C = number of cylinders (tracks) T x number of disks (heads) H x number of sectors S

It should be noted that the storage capacity referred to here refers to the effective amount of data that can be stored in the disk storage. Many other information recorded on the disk are not counted in the storage capacity.

Some people may have noticed that the formatted storage capacity of a newly purchased hard disk does not match the actual nominal storage capacity on the disk. The main reason is that the nominal capacity on the disk is given in decimal, while the computer actually uses binary to represent the storage capacity. For example, 1KB = 1024B, 1MB = 1 048 576B, etc. If MB is used to represent the capacity of the disk storage, there is a nearly 5% error between the nominal capacity of the disk and the actual displayed capacity. If it is expressed in GB, then There is an error of 7.4%. If expressed in TB, the error is as high as 10%.