Thanks. I did get it working once I used an average value as suggested and remembering to put it in as a hex number and not a decimal number.

I did read the chip when it was new and there was no value in that position. I'll see what future ones say.

How did you erase only a portion of the chip? I'm using IC-PROG and perhaps that isn't possible. I'm sure the calibration part of that program is off regardless. Even with a value at that address it always tells me that it can't find a calibration value and would I like to use the one at 3FF. Well, duh. I don't know where it is expecting to see it.

Bart