Hi guys, lfsr 0,0x010 _iloop2 clrf POSTINC0 ; btfss FSR0H,1 ; bra _iloop2 ; gets nut when POSTINC0 overflows FSR0L and carryes to FSROH !! It seems that mchip fixed lfsr but added troubles somewhere else. Now, to clear the blocks I do clearing block by block. Anyway, I do not need to clear very often.. just a delay line for a signal interferometer. If you declare variables with CBLOCK (and program in ASM), do not start from 0. I start from 0x10. Have some debug with ICD2 to discover the reason ! Stefano Curtarolo -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.