HM> So, PROM = EPROM without erase ability,
No, the physical storage technology is quite different. PROMs have sections
physically destroyed by programming.

HM> OTP = EPROM with erase ability but with
HM> the window covered by the plastic case?
Yes though there may be other differences. For instance, an erasable EPROM
has tiny metal shields over the addressing logic and other bits of the chip
that don't like UV. An OTP chip could dispense with those.

HM> Surely plastic wouldn't be 
HM> significantly cheaper than ceramic to make this worthwhile?
Well, apparently it is. Also because the ceramic windowed pack is more
complex to manufacture (the window).

-- Lewin A.R.W. Edwards [Team OS/2]  Tel 0419320415 * 0412809805 * 0414927056
@EOT:

--- MsgedSQ/2 3.35