HM>>> Well, theoretically you could put a PROM (== OTP?) in a plastic case?
HM>>> Plastic would surely be cheaper than ceramic.

>> PROMs are not OTP EPROMs. PROMs are programmed in a different manner. OTP
>> EPROM is just an ordinary EPROM in a plastic case. If you bombarded it with
>> X-rays for long enough, you could probably erase it without a window.

HM> So, PROM = EPROM without erase ability, OTP = EPROM with erase ability but 
HM> with
HM> the window covered by the plastic case? Surely plastic wouldn't be 
HM> significantly cheaper than ceramic to make this worthwhile?

Yep.  The ceramic case with window was over a dollar quite a few years ago
- it's more now.  The plastic molded version has a case value in fractional
cents.  (A RAM chip has a bit extra of fancy conformal coating that puts it
up a tad - but it's still in the order of a cent or two for the whole
casing.)

When the markups come marching in, it tends to peg eraseables at 3 or 4
times the cost of OTP.  Or did last time I priced some.

Regards,
Dave Hatch.

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