> can any one advice me ih how to write a simple compiler? 0. A simple compiler is of little use. 1. If you have to ask, don't. 2. What do you mean by simple? 3. Read the 'dragon book' (aho et al) and a few other books on compiler technology ('a retargetable C compiler' - very good!) 4. Think again. 5. Ask me again (I wrote the Jal compiler for PICs). Wouter van Ooijen -- Van Ooijen Technische Informatica: http://www.voti.nl Jal compiler, Wisp programmer, WLoader bootloader, PICs kopen -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.