Quoted from G-P-E:Note that devices as small as the 27256's are *still* being made but are no longer considered eraseable. They are now available as OTP or One Time Programmable devices. They are plastic encased rather than the pricey ceramic, windowed case. Program it once - if wrong, toss it, get another and try again.
<RANT>
The one thing that irritates the $#!+ out of me on these is that they are listed and sold as EPROMS...the "E" in the acronym EPROM (Erasable Programmable Read Only Memory) stands for ERASABLE! They should be sold as PROMS as that's what they are...is it only me?
</RANT>
Ok, I'm better now. 
