I am trying to monitor whether a register value drops below zero when a subtraction is carried out. Is this possible and how? I understand how the carry bit is used to show a register going over 0xFF, I thought the zero bit would have a similar effect in the other = direction but this is only set when the value is exactly zero. can anyone help me thanks chris -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.