EPROM erase times and lifespan

On Thu, Jan 29, 2009 at 1:16 PM, Dave McGuire <mcguire at neurotica.com> wrote: I have never seen that either... the ones I've worked with professionally have had a variety of features including timers, conductive plastic rails at 0.6" spacing for ESD reasons and easy loading, but I've never seen any sort of eraser that applies power to the chips in any way. I myself did some experiments a couple of years ago at the South Pole when I didn't have a proper UV-A bulb (I just had a UV inspection lamp)... I could get the chips to superficially erase, but when I built a rig out of sockets and a trim pot to turn down Vcc to the EPROM for testing, I could reliably read the former contents at voltages below 5V even when the chips appeared empty at exactly 5V. In the end, I gave up on trying to use the lamp I had. Fortunately I had a couple of 1MBit FLASH chips and was able to muddle through, but in the future, I'd probably pack some 27F256s or pack a real EPROM eraser and use ordinary EPROMs. -ethan