I have a TMS 27C512 right now that has a stuck bit that won't erase. I put the thing in the eraser for 15 minutes. Blank check, and all ones except that bit. Back in for another 15. No change. And another 20 minutes. No change. Must be kaput. On 12/27/2011 10:28 AM, Douglas Goodall wrote:
Bill, Around the same time, I was working at a startup using quite a few 2716's. We were having quite a lot of trouble with them. I came up with a technique for doing quality assurance on them based on checking the content of the EPROM over time while erasing. It seems that some cells take longer than others, and the later portions of the erasing time is spent clearing the recalcitrant bits.