I have an assembler submitted here on programmersheaven. The Delphi code is there. I can also send you the compiled exe if you don't have Delphi.
The assembler uses a textfile to store the machine code <-> assembly statement conversion data. The file can be useful to other people that want to make assemblers or compilers.
The program isn't finished and neither is the instruction set so if anyone wants to help, I'd be thankful.