Latest (and of course best) version of an assembler I play with as a hobby.

http://www.home.earthlink.net/~hxa

Added Motorola SRecord output along with a way to suppress a couple of the record types if they're not wanted. Added a pseudo op that evaluates its argument as a string expression and then pushes it back onto the input (there are also a couple of demos that show how to use this to simulate high-level control structures). Incremental improvement of expression evaluation (if you've ever wanted to apply a unary operator to a string, well, now you can). Bugs both blatantly obvious and sneakily subtle fixed.[/url]

and it'll even run under DOS