Image:Usbkey internals.jpg

From Wikipedia, the free encyclopedia

Wikimedia Commons logo This is a file from the Wikimedia Commons. The description on its description page there is shown below.
Commons is a freely licensed media file repository. You can help.
Former featured picture star This image was previously a featured picture, but community consensus determined that it no longer meets our featured picture criteria. If you have a high quality image that you believe meets the criteria, be sure to upload it, using the proper free license tag, then add it to a relevant article and nominate it.
Wikipedia logo This image was selected as picture of the day on the English Wikipedia for July 31, 2005.

[edit] The internal components of a typical keydrive

This photograph shows both sides of the printed circuit board inside a typical keydrive (circa 2004), in this case an inexpensive 64 Mbyte USB2.0 device. The plastic clamshell case has been removed.

In practice the keydrive consists of only two significant components. The first is the flash memory part (item 4 in the diagram), a generic device that might as easily be found in a digital camera's memory card. The second (item 2 in the diagram) is a device which implements the USB networking and mass-storage interface, and which knows how to make a chunk of generic flash memory appear like a normal disk drive. The high degree of integration in this latter part makes small, inexpensive keydrives possible.

The parts of the device are as follows:

  1. A male type-A USB connector.
  2. An Ours Technology Inc. OTi-2168 USB 2.0 mass storage controller. This implements the USB 2.0 host controller, and provides a seamless linear interface to block-oriented serial flash devices, while hiding the complexities of block-orientation, block erasure, and wear balancing. It contains a small RISC microprocessor and a small amount of ROM and RAM. This communicates with the Hynix device over an 8-line unified address/data bus. This version is a 7x7mm 48-pin LQFP (Low Profile Quad Flat Pack) surface-mount device (info).
  3. JP1 and JP2: two unpopulated 10-pin connectors, used for testing during the keydrive's manufacture.
  4. A Hynix Semiconductor HY27USxx121M series NAND Flash memory device, featuring 4096 independently erasable blocks each providing 16 Kbytes of storage, yielding a total of 64 Mbytes of usable storage. The version used in this keydrive is a 20x12mm 48-pin TSOP1 (Thin Small Outline Package) surface-mount package (info) (datasheet).
  5. An SKC Shin Chang Electronics 12.000 MHz crystal oscillator (XTAL). The OTi device runs the output of this through a phase-locked loop to produce its main 12 MHz clock signal.
  6. A single yellow light-emitting diode (run from a pin on the OTi device) which flashes to indicate activity.
  7. A simple two-position switch, used to indicate whether the device should be in "write-protect" mode. It is shown here in the make position, indicating write-protect is off.
  8. An unpopulated space for a second TSOP1 memory package. The OTi device is capable of driving up to eight such devices. Having this second space allows the manufacturer to choose (generally on a cost basis) whether to use one or two TSOP flash parts.

Surrounding these main components are a number of tiny surface-mount resistors (many of them serving as pull-ups) and capacitors.

For a closeup of an area of this keydrive, see this image.

[edit] Information and licensing

Photographs taken and annotated by John Fader in December 2004 using Adobe Photoshop and Inkscape. This image is (C) Copyright 2004 and (with the exception of its use under the GFDL) all rights are reserved.


GNU head Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation license, Version 1.2 or any later version published by the Free Software Foundation; with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts. A copy of the license is included in the section entitled "GNU Free Documentation license".

Aragonés | العربية | Asturianu | Български | বাংলা | ইমার ঠার/বিষ্ণুপ্রিয়া মণিপুরী | Brezhoneg | Bosanski | Català | Cebuano | Česky | Dansk | Deutsch | Ελληνικά | English | Esperanto | Español | Eesti | Euskara | فارسی | Suomi | Français | Gaeilge | Galego | עברית | Hrvatski | Magyar | Bahasa Indonesia | Ido | Íslenska | Italiano | 日本語 | ქართული | ភាសាខ្មែរ | 한국어 | Kurdî / كوردی | Latina | Lëtzebuergesch | Lietuvių | Bahasa Melayu | Nnapulitano | Nederlands | ‪Norsk (nynorsk)‬ | ‪Norsk (bokmål)‬ | Occitan | Polski | Português | Română | Русский | Slovenčina | Slovenščina | Shqip | Српски / Srpski | Svenska | తెలుగు | ไทย | Türkçe | Українська | اردو | Tiếng Việt | Volapük | Yorùbá | ‪中文(中国大陆)‬ | ‪中文(台灣)‬ | +/-

Originally uploaded by John Fader 17:59, 4 December 2004

File history

Click on a date/time to view the file as it appeared at that time.

Date/TimeDimensionsUserComment
current13:43, 5 April 20081,000×902 (219 KB)Talgraf777 ({{Information |Description= |Source= |Date= |Author= |Permission= |other_versions= }} )
19:32, 18 July 20051,000×959 (490 KB)Solipsist ( ==The internal components of a typical keydrive== This photograph shows both sides of the printed circuit board inside a typical keydrive (circa 2004), in this case an inexpensive 64 Mbyte USB2.0 device. The plastic clamshell case has been remov)

Metadata

This file contains additional information, probably added from the digital camera or scanner used to create or digitize it. If the file has been modified from its original state, some details may not fully reflect the modified file.

Orientation Normal
Horizontal resolution 72 dpi
Vertical resolution 72 dpi
Software used Adobe Photoshop CS Windows
File change date and time 16:41, 5 April 2008
Color space sRGB