Hi, all. I need to write some code to allow rev-ing my PIC's main program with a hex file on a PC and via RS-232 (in the final product and w/o ICD programmer help). I have things set up with MPLINK, with code in the first two 2K pages. I use the USART during normal operations too, so how should I partition the: 1. Loader code 2. Regular app (what I'm upgrading) 3. Common code shared by 1. & 2. (USART xmit, its recv in the ISR) Also, I guess special care must be made that the loader code is golden!! :) Thanks! hooch _________________________________________________________________ Get your FREE download of MSN Explorer at http://explorer.msn.com/intl.asp -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads