They're memory cards (smaller and more expensive than compact flash) used
by other handhelds such as the new palms.

http://www.sdcard.org/

-alex


On Wed, 14 Nov 2001, Warner Losh wrote:

> In message <Pine.SOL.4.21.0111141226550.11740-100000@clarkbar.cs.umd.edu> Alex Chan writes:
> : http://www.neccomp.com/product_leaf.asp?prod_special_no=246
> 
> So what are these secure digital cards?
> 
> Warner
>