Re: Okay, now how do I get them talking?

[mjmahon@aol.com (Michael J. Mahon)]

Laine Houghton replied:

>"Michael J. Mahon" <mjmahon@aol.com>
>
>> Not easily.  The USB connection is more like a network than a bus.
>> It requires a microcontroller to implement protocols and buffering.
>
>My thoughts tend to concur on the network metaphor.
>But those little USB keys don't strike me as having too much smarts
>built in.
>I wish I could find more details on working with them.

Appearances can be deceiving--especially in the age of extremely
dense microelectronics.

Those USB "keys" contain substantially more logic than an Apple II.

CompactFlash cards also contain microcontrollers that simulate an
IDE interface to the flash memory chip(s).

SmartMedia cards contain only a flash memory chip, and therefore
require extensive "controller intelligence" to manage them.

All flash memory chips contain "bad sectors" which are rendered
invisible by the controller firmware.  Another requirement is "wear
leveling", or rotating the frequently updated blocks through the
flash memory, so that no single area is "fatigued" by being too
frequently re-written.

Flash memories are not as much like disks as their controllers
would like you to think (although the integral CompactFlash
controller does a good IDE simulation.  ;-)

-michael

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