for $8D definition file, i am using starting address of 8000hex. Should the buffer address be the same? Using a Moates BURN1. I normally burn the 29C256 chips with a 16k bin, and start at 4000hex. So i know the BURN1 is good.
when i read the chip back, it does not verify, and shows FF for the first half and 00 for the second half.
Need help!

WEnt to that site and did everything correctly. The PROM I/O succeeds, but when i verify chip to buffer, it does not. Says not matched. i can look at the buffer, and there seems tobe code there, then it goes to all 0s after a while. i might just try this chip in my ECM.

Dont have a spare 512 chip to try do you? Perhaps reinstalling the moates driver and reinstalling your tuning program?
Just throwing some things out there.

Yea i did the driver thing, and got the latest version of flash and burn. Tried several of 256k and 512 chips, same result, it would burn but not verify. i been talking with Moates support, they think my burner is bad, thus i think i gotta send it back.

sorry to hear that,
just burned a couple of 27SF512 chips today without problem
Not sure if the Burn1 is the same as the Burn2 but it was giving me weird problems like you are describing because I had the chip in the wrong end of the burner. Facing the right way but in the wrong slots in the burner.
A noob mistake but these are my first ones.