>I wrote this test program and simulated with MPLAB Thank you for your effort Tony. Your code does indeed write a block correctly. As did mine, which for some reason came right (at least twice anyway) last evening However, the chip will still not write without the block being blanked by 0000 at programming time. If I can't solve that then anything else is academic Thanks again Joe ----- No virus found in this message. Checked by AVG - www.avg.com Version: 2016.0.7797 / Virus Database: 4656/13181 - Release Date: 10/10/16 --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .