Yes, you'll need to be running the EC version of the target emulator in
order to use the "ec" command. The ideal way to test your program is to
compile the program for EC (error-checking) and run it on the EC target
emulator (on a second PC, not a PDA). When you've completely finished the
program and you feel it is ready for release, then you compile it for NC
(non-error checking) and test it on the actual target device, whether that
may be a PC, PDA or smart phone.
The reason you want to develop under the error-checking version of the
emulator is that you'll find a lot more bugs that way. The EC version of GEOS
checks nearly every parameter to every function, and gives better error
messages than the NC version (or standard version). Thus, you're more likely
to find the bugs before you release the product to the public.
Nathan