Please login in order to download photos in full size
If you are not registered, please register for free: www.Free-Photos.biz/register
Please note to download premium images you also need to join as a free member..
You can also save the photos without the registration - but only in small and average sizes, and some of them will have the site's watermark. Please simply click your right mouse button and save the image.
Please login in order to like photos
If you are not registered, please register for free:
Sorry, non-members can download up to 100 full-size photos per month.
It looks like you have used up your limit.
Free members can download an unlimited number of full-size photos - including the premium free photos.
Join as a member today for FREE! - and download the images without limitations:
You can also save the images without the membership - but only in small and average sizes, and some of them may have the site's watermark. Please simply click your right mouse button and save the image.
The internal components of a typical keydrive
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:
- A male type-A USB connector.
- 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).
- JP1 and JP2: two unpopulated 10-pin connectors, used for testing during the keydrive's manufacture.
- 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).
- 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.
- A single yellow light-emitting diode (run from a pin on the OTi device) which flashes to indicate activity.
- 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.
- 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.
For a closeup of an area of this keydrive, see this image.
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.
|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.
|This file is licensed under the Creative Commons Attribution-Share Alike 3.0 Unported license.|
|This licensing tag was added to this file as part of the GFDL licensing update.
Originally uploaded by John Fader 17:59, 4 December 2004
GNU Free Documentation License
While the copyright and licensing information supplied for each photo is believed to be accurate, Free-Photos.biz does not provide any warranty regarding the copyright status or correctness of licensing terms. If you decide to reuse the images from Free-Photos.biz, you should verify the copyright status of each image just as you would when obtaining images from other sources.
The use of depictions of living or deceased persons may be restricted in some jurisdictions by laws regarding personality rights. Such images are exhibited at Free-Photos.biz as works of art that serve higher artistic interests.