Hi I have a AT45DB041B connected to the ICSP of the atmega644 and stores data ok.
I am trying to replace it with the through hole AT45D041 which seems identical to me apart from the 5v requirement, but this one does not work.
Aren't these identical memories, maybe there is something I am missing?
Many programmer's tools check the chip device ID and refuse to download the code if the target differs from the part selected, unless you uncheck this option - when available. Even a bare suffix added on the part number very often is enought to make a change in their ID's. Are you aware of that?