The types and features USB and flash drives

Whom are not a secret, what is it? Where where to insert in the phone. On the this theme will be only explanatory. Let's start the subject with flash drives, memory cards and smoothly finished about USB.

Flash drives

Why we need flash memory, memory card? The answer is very simple. It is used in cellphones, digital cameras, navigation devices, MP3 players, etc., without which we cannot live. Their main goal:

  • to Save the information received from the device
  • to Transfer information from PC to device and reverse process
  • because they work with independent power supply (batteries, accumulators), it should have low energy consumption
  • Independent power, that is, must save all the information
  • high-speed (exchange of information) depends on how to work your camera
  • compact
  • There is a great variety, but I'll just talk about running Card, with whom we most often encounter:

    Compact Flash (CF) is a removable media device with a parallel interface. Have a 50-pin connector and communication speed up to 33 MB/s and a volume of 130 GB. Popular digital cameras. Support 2 modes of operation:

  • PCMCIA - standard card input / output
  • the

  • IDE (ATA) interface for use as a hard drive
  • In principle, the most nimble of all the memory cards, but the largest size.

    Compact Flash (CF)

    Memory Stick Duo is the card's flash memory have a serial 10-pin interface. Developed by Sony and are used in this product

    Memory Stick Duo

    miniSD - modern memory card designed for portable devices like mobile telephones, navigation devices, MP3 players, ebooks, etc. that are small in size


    MultiMedia (MMC) - removable flash drive consists of a plastic housing and seven of the contact interface, used only six can run in SPI mode and MMC (data transfer protocols)

    MMC command can be transmitted with frequencies up to 20MHz
    SPI is part of the MMC Protocol defines only the wiring, not the entire data transmission Protocol, through this cheaper option

    MultiMedia (MMC)

    SD - same as MMS, but there are differences:
    1. Two bus data transfer more
    2. There is a protection against overwriting


    SmartMedia - contains on-chip architecture, NAND, can be assembled without soldering on a flexible plastic substrate and contains only the contacts and the memory chip, a small amount to 256 MB. Voltage of power: 5V key area is to the left, 3B on the right.


    xD-Picture - used in modern cameras Olympus/ Fujifilm. Write data rate - 3 MB/s read - 5 MB/s, and size from 256 MB to 2 GB


    Introduced classification of speed characteristics of cards and devices to work with them, the so-called the SD Speed Class.

    SD Class 2 — (writing speed not less 2 MB/s — 13x
    SD Class 4 (write speed of at least 4 MB/s) — 26x
    SD Class 6 (write speed of at least 6MB/s — 40x
    SD Class 10 (write speed of at least 10MB/s — 66x
    SD Class 16 — (write speed minimum of 16 MB/s) — 106x

    SD Speed Class

    Flash memory, memory card (Card) is all built into the device have the characteristics described above and does not interfere with us. But there are external plug - USB is connected to external USB flash drives:

  • Greater capacity
  • More sizes
  • More speed
  • More consumption current
  • USB flash drives

    There are several standards (sockets) to connect them:

    USB A

    USB A - standard four pin connector, which can connect directly a USB stick or other equipment that can work with this connector

    USB B

    USB B is used, usually, peripheral devices (scanner, printer)

    USB mini

    USB - a complete analogue of the USB A, only has a compact appearance, the connection is through a transition cord

    But all this appearance, and USB spent a few cycles of life:

    USB 1.1. - Computers that were released before 2002, provide a USB 1.1 interface. Data transmission according to this standard is rather slow. The theoretical peak throughput is 12 Mbps (or 1.5 MB/s). For input devices – keyboard and mouse – that is enough.

    USB 2.0. - Computers and laptops released after 2003 have USB 2.0 ports. Maximum speed in comparison to standard 1.1 has increased significantly and amounted to 480 Mbps (or 60 MB/s). Although, in practice, to achieve this level of throughput is not possible.

    USB 3.0. - promise to increase bandwidth up to 5GB/sec. It has eight ends and painted blue, so as not to confuse. When connecting the interface USB 2.0., switches automatically to the same standard.

    USB 3.0

    For connecting hardware, you usually use the USB 2.0.. This ultra-fast, super-bulky stick will not go there. We need to see the user manual of the device, usually up to: 2GB, 4Gb, 8Gb. Format should be in FAT 32, as household appliances used for listening, viewing or recording music, speech, pictures, films. Do not ignore the body design since it should be easy to use. Suppose this case:

    USB 2.0

    Like the stick as the stick, looks compact, no sharp corners, but when using there is a lot of problems. If you use USB extension, then no obstacles do not occur, except the additional weight and bulk in your pocket:

  • close to two usbишки - mouse and thumb drive next not intermeddle
  • USB is located in the housing and along comes the wall, you stick in the socket and the holder under the wall and a finger does not climb. In the end, the flash drive in its own housing.
  • I believe that the choice of drives, such nuances need to pay, and that turns out is not a portable option.

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