Thanks for the help guys. Attached is the 'real' block 0. Greg- All your calculations were correct and did get me to block 0. I had some problems initially as the editor I was using (wxHexEditor) was displaying the row offset in decimal not hex. I am familiar with the Intel HEX format (I am an engineer) and expected the offset to be in hex automatically. I couldn't get the offset to display in hex so I had to convert things. I finally realized if I right clicked in the offset column it rotated through the different base systems. I know I'm sounding long winded but my point is these forums are for helping others; if someone is stuck and wants to understand and do this manually, hopefully they have enough cookie crumbs to do so.