Craig Lee wrote:
>
> So what you are saying is that the OTP devices are the most in-vulnerable?

At some point of view, yes.  The erasable devices, as E2prom, Windowed
Eprom and Flash, has the block bits also erasable, they make part of the
regular memory bits, what means, if the device is protected, you can
turn off the protection bits if you erase the whole device, than by some
way one could erase just the protection bits, or part of the code too,
but it means the device *is not* totally protected.

By the other side, it is very difficult to flip a bit in a non windowed
eprom device as OTP, probably a strong electromagnetic pulse could do
it, and probably also destroy the device, but it is more difficult than
the others above.  The masked ROM version (and PROM if any), apparently
are the ones with best protection, since they have no programmable way
to be able to read back the programmed code, or because its "unprotected
bits" doesn't exist, or because they are fused as a PROM device is, so,
once the fuse is burnt, there is no possible way to rebuild it, thus,
reading the code contents.

So, Imagine you are a company not so much honest, trying to do some
piracy, you would buy a thousand units from your competitor, and start
to do pre-erasing, or fast erasing pulses, until by any luck, you got
the protection bits erased first, perhaps with part of the code, but the
rest of the code would be exposed.  Now, windowed eprom devices, looks
to be easier, since one could focus UV light in tinny spots over the
silicon die, and trying to find exactly the location of the protection
bits, erasing them only!!!  UV is a high frequency and could be focused
in very tinny spots.  I would not trust windowed eprom devices so easily
as to be highly protected.

Somebody said that piracy is a bad thing, yesssss it is!  Even worse
when you make money selling what is not yours by right.  I may be
confused a bit, and I apologize if I am wrong, but it was not Microsoft
who sold (without Steve Jobs's permission and profit) Apple "Windows" (a
free gift from HP?NCR? to S.Jobs) to NEC many years ago? ahaaaam, why
crack a chip if you can have somebody else's source code?

Hey Bill, is that right? or they lied about it too?

Wagner.