More HN27C301 burning shenannigans

[guitarzombie]

Happy holidays everyone.

So ive been burning some 27c301s without any problems using my Willem g4qx. Only recently ive been getting some weird problems.

At approx. 50%, exactly half way of the burn (address 10000) it always fails. Tried a bunch of chips. Within the same batch i have burned accurately but 2 out of 10.

Chips were blank. So i investigated, so I wanted to read what was burned on the 27c301. Not only did it burn the entire chip, but it seems to have doubled the first 0-FFFF to 10000-1FFFF as well. Im guessing this is a jumper issue some how. And the first bank burned correctly, as did the second bank, if it was doubled. But im not (im using all 128k of the space)

[guitarzombie]

Even tho I didnt get a reply I fixed it by buying a 40 pin socket and wiring it to be used by my willem.

I was more curious why when I read the data and it failed at 50%, why the other half of the chip mirrored the first half, instead of it being all blanks (FF)

[lidnariq]

Sounds like it was confused about which pin was which, causing half the capacity to appear to be missing.