eprom is out of a '7747. I like to zero out them out before they go into my eraser. However this one cannot be written to, which leaves me afraid that if after it is erased, it will not be writable. (currently it has has factory 1990 5.0L TBI image)

When flashing these 7747's 27c32, any special voltages needed? Never had this issue before but I know there are some older eproms who require high voltage to burn.

Any thoughts?