USB Drives, Thumb Drives and Flash technology

 By Lee Brannon

Originally written 1/23/08
Revised - re-posted 1/31/09

Flash drives, USB Flash drives and flash memory technology has fascinated me for the last couple of years.  For the  purpose of this discussion I am just going to give you the general principles. (If you want to know more about the technical issues start by looking up Fowler-Nordheim tunneling.  I suggest www.howstuffworks.com)

There are lots of different types and brands of Flash drives and Flash memory, but the only real distinction is  that the term "USB Flash drive" is used to indicate a mobile device and a "Flash Drive" is basically a hard disk that uses the flash technology instead of a magnetic platter/disk to store data. Mobile Flash drives, USB Flash Drives, Thumb Drives, Memory Sticks, USB Drives , or whatever you call them are becoming cheaper and easier to find every day.  There is some contention as to when the first USB Flash Drive was developed and sold, but somewhere between 1998 and 2000 the first ones hit the market.  Wikipedia has a history section that covers this.

One thing you should be aware of is that not all drives and cards use a common standard.  For example the Sony Memory Sticks can only be used in computers equipped specifically for those storage devices.  If you need to use a storage device such as a memory card you will need to make sure you purchase one that will work with your device. 

We are going to concern ourselves here with the common flash/thumb/USB drive although most of the discussion applies to many of the devices.

The benefits of using a thumb drive are many.

• Fast and easy low cost storage.
• Quick connection to the device or computer.
• Large capacity.
• Easy to carry.

The most common drive and or card readers work with USB connectors and are generally refered to as USB drives or thumb drives.  Nearly all computers built in the last few years have USB ports, but you also need to be aware that older computers will have the slower USB 1.0 ports and not the USB 2.0 standard of today.

So how does a flash/thumb/USB drive or memory card store information?  The first thing you need to know is that they all use a chip technology referred to as NAND.  NAND chips use transistors.  You can think of them as tiny gates or doors that stay open or closed to represent the bits that are on or off .  More exactly there are pairs of these transistors and the electrical flow between them determines the on and of state.  One transistor or gate opens and a sensor determines the number of electrons passing between the transistors.  So you can think of it like one of the transistors opening and thereby reducing the number of electrons.  You can think of it that way but actually there are no moving parts.  The open or closed gate is actually determined by how much current is passing through.  Like I said you may want to read Wikipedia for the general stuff and go to Howstuffworks.com for details.

So, how reliable are they? It is my understanding that the transistors are good for about one million read/writes which sounds like a lot, but considering that the drives read and write in whole "blocks" you could hit that number fairly soon. My personal experience is all that I can attest to.  I have been using an 8GIG SD Cruzer drive for well over a year now on an almost constant basis and it has never failed.  I have also been using an SD micro card in my phone for longer than that and it is used daily.  Some Thumb drives I purchased recently had a 5 year warranty on the package.

Part of my fascination with this is that in that tiny thumb drive (One name for a USB flash drive) is sixteen times more storage than the largest hard disk drive I owned 6 years ago!  I put every installer for every utility that I am currently using onto one and it did not use 1/8th of storage space!

Early affordable USB Flash Drives and Memory Cards came in capacities of MB or megabytes.   The most popular ones came in 128Mb and 256Mb sizes. They were impressive at the time.  After all, storing your camera pictures on a small device or SD card was impossible in the years prior.  However, the estimate was that Flash Drive storage space would double about once every two years.  This has not proved to be true.  Instead it is doubling every year!  My huge 8 GIG from last year has already been surpassed with a 16 GIG (gigabytes) and 32 GIG model

Of course small storage USB Flash drives are already laughable.  Last year I was in a line at a Kmart and I saw some on the candy rack.  They were only $5.99.  Of course, when I looked close I saw that they were only 64MB.  I chuckled out loud.  During this last Christmas I found Kingsington 2GIG drives at WalMart for $5.00 Something that upon reflection seems strange, since just a couple of years ago that drive would have been worth five times that amount!

There are 500GIG Mybooks and other brands of USB external drives for around $100 now. These drives make it cheap and easy to setup a backup for your data or to add more space to your desktop machine.  Keep in mind that those transistors may wear out and that it is best to rotate large drives using this technology,  That way you have a backup.

What does the future hold?  Possibly entire notebook computers that are entirely based on Flash Drive NAND technology or a variation of it.  There are draw backs.  The transistors or gates I talked about are only good for about one million uses before they wear out.  Since data is written and read in blocks of transistors that means they could prove not to be a long lasting storage media for a laptop.  When you read one single character that is stored in the block the entire block gets read.

Concerns:

Thumb drives give you many advantages, but you should be aware of some of the pitfalls of using them. 

• If you work in an area that has sensitive data your employer may not allow thumb drives to be used. always check before bringing one to work. 
• Thumb drives can be setup to launch applications when they are connected to a computer and that could cause a serious issue if the drive contains a virus or spyware or other malicious code.
• Always password protect and or encrypt your drive. Most thumb drives have this ability installed, but if yours does not you can find an application on the web that will take care of the problem.  I know of several local gas stations and convenience stores that have had thumb drives left on the counter. I have found some myself in parking lots.

BTW: Keep your eyes open.  There may be a collectors market for unusual USB Flash Drives someday.  I have already seen a keychain Bible that is a Flash Drive with the entire King James bible on it.  There are others shaped to look like unusual items.

The following links will take you to some unusual USB Flash Drives. 

USB FLASH DRIVES that look like robots, food, .... http://www.quickonlinetips.com/archives/2007/12/strange-usb-flash-drives-on-amazon/

Need to open a bottle?  Just whip out your USB Flash Drive http://designcorner.blinkr.net/OhGizmo_/2007/04/25/Popdrive___USB_Flash_Drive___Bottle_Opener

 Are you a secret agent who needs to hide top secret documents? Check out this watch...

 http://www.yankodesign.com/index.php/2007/03/30/kronos-usb-flash-drive-watch-by-andrew-wilkerson/

A Thumb Drive that looks like a thumb ...

http://www.gearfuse.com/index.php?tag=usb_flash_drive

 Need a classy Ducati?

http://www.ifa-show.com/0061/sandisk/storage/sandisk-extreme-ducati-drive/