Isaac Marino Bavaresco wrote: > If I don't register somewhere each block as it is received, the only > way > to tell if a block was already received would be to scan it from begin > to end to find a value different to 0xff. > Besides being too time-consuming, if a block full of 0xff is received > it > will always be detected as not received. OK, so you use a single erase block somewhere with individual bits corresponding to uploaded blocks. These bits start out as 1 and you flip them to 0 when the corresponding block is received. In any case, you shoul= d checksum the whole uploaded image before attempting to write it to the app area. However, what does this have to do with the bootloader doing word versus page writes? ******************************************************************** Embed Inc, Littleton Massachusetts, http://www.embedinc.com/products (978) 742-9014. Gold level PIC consultants since 2000. --=20 http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .