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Question: CRC Verse Checksum Verification for USB Flash Drives?

Is Checksum or CRC better for checking data written to USB flash drives?

This post is to give the general user an idea of what verification method is better for writing data to a flash drive.  There are reference links at the bottom of this post which dive much deeper into the two methods of verification if this simple overview is not enough.

The short answer is Cyclical Redundancy Check or CRC is the best method for checking data written to a USB flash drive.

Many believe a checksum is the best method to verify data written to a flash drive (most popular is MD5).  I believe this is favored because it is easier to understand how the verification works, and also easier to implement.  However, there are flaws in checksum verification and therefore not suitable for verification of data written to a flash drive.

What is the difference between Checksum and CRC verification?  The checksum method uses addition in its math calculations to check whether all data was written correctly.  CRC uses long division in its math calculations to check whether all data was written correctly.  It is worth noting I am talking about binary long division, not the school-yard long division you so fondly remember.

Checksum methods will calculate the total bits in a packet of data and include that total checksum amount when the data is sent over communication lines.  The receiver will then look at the packet, read the checksum value and then perform the same calculation to make sure everything adds up.  If the calculation on the receiver’s end matches the value passed in the packet, all is good.  The problem is a high probability that somewhere between the sender and receiver the bits of data are changed, corrupted or swapped yet still turn a correct checksum value after calculation on the receiving end.

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Alaska Airlines adds USB Ports with Power

Alaska Airlines passengers will now be able to use their tablets, book readers, and cellphones all the way from the gate to thousands of feet in the air. Starting Nov. 9, passengers will be able to use their electronic devices on board the plane, and even use WiFi, at 10,000 feet in the air.  Alaska Airlines will start flying its first aircraft with 110-volt and USB power outlets at every seat next month. Most of the fleet will be equipped by the end of 2014. Continue Reading

Nexcopy Adds New Standalone SD Duplicators With SD Card Sanitization Features

SD duplicator, stand-alone Press Release:  Lake Forest, CA – November 5, 2013 – Nexcopy Inc., a leading manufacturer and developer of flash memory duplicators, introduces two new standalone SD Duplicator models to Nexcopy’s line of flash memory duplicators and sanitizers.  The 1-15 and 1-31 target systems offer unparalleled copy speeds to Secure Digital media with additional functions for device sanitization. Sanitization features available by the new Nexcopy SD Duplicators include full binary overwrite feature in both single pass and triple pass random write sequencing.  The proprietary triple pass overwrite method developed by Nexcopy insures all data of a secure digital card cannot be recovered or restored through forensic process. These new standalone SD duplicators by Nexcopy can sanitize multiple devices simultaneously saving IT professionals valuable time in flash memory management.  Core functions of these new systems include the binary copy process used in the popular Nexcopy USB duplicators systems.  Binary copy modes include the ability to copy bootable SD media, FAT, FAT32, NTFS, ext2, ext3, ext4 and any other file format system, proprietary or public. “Pivoting from our core binary copy firmware, Nexcopy expands our technology to include Continue Reading

Peddle to the Metal with USB 3.1 Spec

The Universal Serial Buss Implementers Forum or USB-IF has released their new specification, USB 3.1.  The full spec will be available for download off the USB-IF website on Friday Aug 2, 2013.  The new specification allows for 10Gb/s transfer rate.  Of course this is optimal transfer speed without the incurrence of operating system resources trying to regulate bandwidth for multi device transfers, but none-the-less it’s a huge jump in speed for USB.

USB 3.1 cable

USB is the most versatile connector type in the computer market.  Universal Serial Bus (USB) is an industry standard developed in the mid-1990s that defines the cables, connectors and communications protocols used in a bus for connection, communication, and power supply between computers and electronic devices. Originally USB was specific to connect computer peripherals such as keyboards, pointing devices, digital cameras, printers and network adapters.  With the increased need for bandwidth with digital content and the faster speeds of portable storage devices and smartphones the need to increase the speed of USB has been significant. In addition the USB specification incorporated a Power Delivery or PD protocol which can deliver up to 100watts of power over a USB cable.  The PD technology must use a certified cable with the Power Delivery wiring so not all USB cables will have the PD ability.  The intent is to permit uniformly charging laptops, tablets, USB-powered disks and similarly higher power consumer electronics, as a natural extension of existing European and Chinese mobile telephone charging standards. With the increased 3.1 speeds and the power ability of 100watts per cable it appears USB has made a substantial gain in the cable of choice for manufacturers and consumers a like for connecting their peripherals to their host computers. The USB 3.1 specification is just now in development and products should come to market in the next 8-10 months. Continue Reading

USB ScanStik with Voice Notes

Planon is known for having pen-sized scanners for mobile scanning of business cards, documents, lecture notes and more.  What Planon continues to do is develop the scanning technology year after year. The company has just released it’s latest pen scanner, the ScanStik SK600V.  The V is for Voice Notes.  It’s now possible to scan from a device the size of a writing pen and include voice memos for the scanned document.  Nice. They have also added bluetooth connectivity, but apparently the “b” didn’t make it into the updated part number. You can scan at 600dpi (dots per inch) and save the file to a microSD card.  Once you are ready for download, you can connect to a host computer via USB and off-load all those trade show business cards (or competitors spec sheets of that product not yet released). Continue Reading

How To: Minecraft on USB Stick

Minecraft has taken on a life of it’s own. From 5 year old kids being obsessed with Minecraft to adults making movie trailers it’s a strange little obsession for digital lego’s that look like CAD drawings. Either way, you might find this post useful for how to make a portable Minecraft USB stick. With a portable version of Minecraft you can now play the game anywhere, school, library, work, you name it. This is how you do it: (Download Portable Minecaft rar now)
  1. Download portabal_minecraft.rar
  2. Extract Minecraft folder to Memory stick  *Need program to extract .rar file, just Google “extract rar”
  3. Open the Run.exe
  4. Log into your Minecraft account and let it update for you
  5. That’s it!
The resultant USB will have several items in the root of the USB.
  • .minecraft folder with all your assets
  • Minecraft exe file which is the program
  • Start.bin file, which generates Minecaft when you start
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(Infograph) History of Portable Storage Devices

The history of portable storage is an interesting one and starts earlier then you probably think.  Starting in 1928 the punch card is what started it all.  Like the punch music you probably remember on your grandmothers piano where the piano played automatically from the punch roll. History of Portable Storage (Infograph) – An infographic by the team at History of Portable Storage (Infograph) Continue Reading

ECCN and HS Code for USB Flash Drives

When importing or exporting USB flash drives in the United States you will want to use these ECCN and HS Codes to help with customs paperwork. The ECCN Code for a USB flash drive is:  EAR99 The HS Code for a USB flash drive is:  8523.51.0000 In the event your freight forwarder or delivery service tells you that an ECCN is needed to ship USB flash drives and is required to complete the Automated Export System (AES) or other documentation then please give them the above information and it should all work out. ECCN stands for Export Control Classification Number.  An ECCN is an alpha-numeric classification used in the Commerce Control List to identify items for export control purposes. HS Code is the  “Harmonized System” which is a 6-digit standardized numerical method of classifying traded products developed and maintained by the World Customs Organization.  The Harmonized System system (HS) forms the basis of all countries’ tariff Schedule all over the world.  Or it helps countries asses value to a product in a standardized way and by definitions all countries can agree and interpret. Continue Reading

8 Technology Gadgets To Boost Your Business

SmallBizBee posted a nice article today about eight tech gadgets which can help boost your busines in either profit, production, efficiency or exposure.  Click for the full article and how these items can impact your business.  For a quick read we have the summary:
  • ConnectMe Home Phone Adapter
  • USB Duplicator for data loading by Nexcopy
  • Wireless Solar Keyboard
  • Noise Canceling Headphones
  • MIFI Liberate
  • HDMI Pocket Projector
  • Absolutepower Charger
  • Touch Mouse T620
Source:  SmallBizBee.com Continue Reading

Protecting IP on USB

The above InfoGraph was provided by Nexcopy Company and highlights the current and services available for protecting intellectual property on USB flash media, or USB Copy Protection.  The concept behind this USB copy protection solution is the ability to share digital files on a flash drive with others, but restrict their ability to pass along that information. With the above solution a user can protect different file types which are the most popular multimedia files such as PDF, MP3, QuickTime, MP4, M4V, html, flash and some other listed.  This post is not intended as advertising, but a share of products and services about USB copy protection available on the market today. Continue Reading

Longevity of USB Flash and Wear Leveling

I think we have all heard a USB can only be used so many times.  Some say the number is 1,000 writes – some say the number is 100,000 writes.  One thing I do know for sure, it’s impossible to tell on any one specific device.  The life cycle of a USB is directly related to the flash memory…and from model to model or style to style, who knows what quality of flash is used.  With that said, we can still explain the theory behind making USB drives last longer.  For the most part it boils down to several elements  A)  the memory type and quality and B) the wear leveling technique. As a quick summary the NAND flash in USB can be either SLC, MLC or TLC (single cell, multi-layer cell or triple-layer cell memory).  Typically you will find MLC and now mostly TLC in USB sticks.  SLC can be found but typically on the very high end devices. Wear leveling is a technique to prolong the life of the erasable flash memory.  To summarize, flash memory has individual, erasable segments that can be set as zero’s or ones (set as either positive or negative charge).  However, after a certain number of erase and write cycles the segment (cell) becomes too unstable for reliable use. Wear leveling is the algorithm used by the controller on the device which attempts to arrange the erase and writes evenly across the flash medium.  Typically flash can have a cycle between 3,000 and 5,000 erase/writes.  In addition to the usable area, the flash also has some cells with specific blocks for extended live which can handle up to 100,000 writes.  This is the area where the controller makes not of the segments previously used and maps out the next best cells to use during an erase/write cycle. There are three types of wear leveling. No wear leveling – A Flash memory storage system with no wear leveling will not last very long if it is writing data to the flash. Without wear leveling, the Flash controller must permanently assign the logical addresses from the host computer to the physical addresses of the Flash memory. This means that every write to a previously written block must first be read, erased, modified, and re-written to the same location. This is very time consuming and highly written locations will wear out quickly with other locations even being completely unused. Once a few blocks reach their end of life the drive is no longer operable. Dynamic wear leveling – The first developed type of leveling is called dynamic wear leveling and it uses a map to linklogicl block addresses from the host to the physical Flash memory. Each time the host writes replacement data, the map is updated so the original physical block is marked as invalid data, and a new block is linked to that map entry. Each time a block of data is re-written to the Flash memory it is written to a new location. Static wear leveling – The other type of wear leveling is called static wear leveling which also uses a map to link the block addresses to physical memory addresses. Static wear leveling works the same as dynamic wear leveling except the static blocks that do not change are periodically moved so that these low usage cells are able to be used by other data. This rotational effect of block addressing enables an SSD to operate until most of the blocks are near their end of life. The above are three types of wear leveling and there are three types of techniques used to extend the life of a USB drive. Error correction – Code which is kept and logs bad blocks so they cannot be used again in future writes. Pool reserve – Where if a write fails to a block it can be re-routed to the pool of reserved blocks and written there. Track usage  – Blocks on the media can be tracked in a least recently used queue of some sort. The data structures for the queue itself must be wear leveled as well as this queue information is constantly changing. Source:  Wikipedia and Nexcopy Inc. duplicator manufacturer. Continue Reading

Rip and Tear Gigabytes To Go

Burning CDs is slow and impractical when at a clients site.  In addition, who wants to leave behind their 16GB flash drive with a mix of personal and professional information?  With that said, we designed a small pack of drives we could tear and use when needed.  Since we travel and present files to clients this gives us an easy, inexpensive and creative way to leave files with the client. The design lends itself to the old-school flyers you’d see around town for a local band playing at a pub or someone looking to offer odd-job services.  The physical form factor says it all…quick, easy, here-ya-go. Each pack of four is recycled paper used as it’s chassis/case and COB memory and USB connector (Chip On Board) for the memory.  Each tab is perforated for easy tear and use functionality. The designer Kurt Rampton of Bolt Group offers the drives in a couple different Continue Reading

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