Peter wrote:
snip
Yesterday I got another copy of the U.S. Flying magazine through my
door and looking through it I see loads of vendors selling aviation
related software products (Anywheremap etc etc) on the ls800. I just
cannot believe that this issue has not come up before. It is as if
nobody in the USA flies unpressurised above 14k feet, which I am sure
has to be rubbish.

The reason more EFBs don't support a flash drive is that merely
replacing the hard drive with a big flash drive is not the proper
solution. The problem is compounded by the fact that most EFB vendors
are not embedded systems engineers. They simply want to treat the EFB
platform as a standard PC on which they install the OS (Windows), their
application software (flight planner, etc), and be done with it. If you
want a reliable EFB solution, that is clearly not the answer.

The problem is flash memory excels only as a read-only medium due to its
write cycle limitations (both in terms of speed and number of cycles).
If you're updating your application data on the flash every 28 days (or
even once a week), that's no problem, but if you install the OS such
that it operates directly from the flash drive, the constant writes to
the swap file and other meta data will kill the flash in short order.

The benefits and limitations of flash memory are nicely outlined he

http://en.wikipedia.org/wiki/Flash_memory

In order for a flash drive to effectively replace a hard drive in this
application, you have to do some engineering to load an OS image from
flash and execute it entirely in ram. AFAIK, Windows (the consumer
version at least) cannot do this.

-Doug

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Doug Vetter, ATP/CFI

http://www.dvatp.com
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