ZXDS is an emulator of Sinclair ZX Spectrum for Nintendo DS, written by Patrik Rak. It is steadily reaching a mature stage of development, and it already has some noteworthy features, like accurate emulation of Spectrum 48k, 128k and Pentagon models (including sound), or support for TAP/TZX/PZX tape files, TRD/SCL disk files and RZX playback files.

Changes:

+ Proper save requester, including support for basic file management operations.
+ Alternate between two different directories by tapping the save/load file icon again.
+ Quickly switch models in load requester with various L/R+X combinations.
+ Risky operations now use confirmation requesters.
+ It is now possible to step the emulation frame by frame.
+ Added pouet.net and Tipshop pokes library to servers.cfg.
* Implemented HTTP redirects, required by some pouet.net sites.
+ Directly poke decimal, hexadecimal, or binary values in the data dump view.
* Switched to PNG for background and icon graphics. The BMP support remains, but note that some names have changed – check skins/readme.txt for details.
* Augmented the 128k keyboard graphics with symbol characters. Thanks, Paddy.
* The selected keyboard is now saved to the config file.
* Distinguish the load and save slot screens with colored slot frames.
* Disable the keyboard matrix effect during multiplayer session. It is often difficult enough to configure the controls even without it.
* Switching to maximum speed while loading tapes in fast mode now disables the display updates entirely. Handy for slight speed boost if you feel desperate.
* Other subtle changes (nicer boot message, increased cheat poke limit).
* Fixed loading of Pentagon SZX files (ROM paging, step direction).
* Minor bugfixes (libfat mkdir and aliasing, ZIP long name skipping).

Thanks to http://nintendomax.com/viewtopic.php?t=14256&f=19 for the news.

http://zxds.raxoft.cz/