> On a different note, is there a circuit diagram of the TI-83 available? You might want to check out the Z80 cpu manual. It has a section which deals with hardware and software implementation. Didn't read it, but it might help you a bit. http://www.zilog.com/docs/z80/z80cpu_um.pdf ----------------------------------------------------- Mail.be, Free WebMail and Virtual Office http://www.mail.be