On Wed, 25 Jul 2001 19:57:30 -0400, Ron Anthony wrote:

>David, with all due respect, and to be perfectly and objectively factual,
>with no reasonable debate about it, Microchip TOTALLY BLEW IT on the flash
>part.  Case closed.  They blew it so badly that between the 77 and 77A, they
>completely revamped their fundamentally flawed design.  They made some
>horrendous design decisions and committed them to silicon with the 77.  It's
>a flash part, but if you want it flashable, it must be naked.  If you want
>it secure, you must turn the flash into OTP.  This couldn't be a worse
>situation.



your thinking is fundamentally flawed already. it's perfectly secure as a part you can reprogram as many times as
you like. i know this, because i've done it, hundreds of times already.

flash the chip / erase the chip / flash the chip / erase the chip . . . ad infinitum

there is nowhere in that cycle that anybody can get to your code. it's secure.

when the write protect is on, you can't flash the chip, it must first be erased, which means the chip is perfectly
secure, and perfectly reusable, as many times as you like. i simply can't understand why you can't see this; it's
not even close to a OTP part.

somewhere along the line you've gotten a poor understanding of how the flash / code protect works together.  i
don't know where you got this bad info but i think you need to step back and look at it anew.



>
>Now don't get me wrong, it is a great chip.  As far as designing for the
>wrong part, this could not be further from the truth.  It is what was
>available, and we designed for it.  However, to overcome the chip's
>weakness, I'm at this very moment spending hour after hour on a
>mind-numbingly complex kernel that every thread must jump into code
>protected space and out again, to keep the code secure.  And the encrypted
>bootloader?  Unbelievably complex.  All this wasted effort to overcome a
>very bad design decision by Microchip. And that the 77A was slated for
>release more than 7 months ago?  Inexcusable.  Basically, Microchip was
>aware of the code protect flaw but determined that a part that was selling
>well (the 77) didn't have pressure on the revision A to come out, what's the
>big deal if it slipped and people's code gets whacked by their respective
>mortal enemies?  By the time the 77A ships, AFTER the 18F series, it will
>have been more than a year late.  Why??  For a die shrink?  Come on.


again, this is all based on your presumption that the part is flawed, which it clearly is not.  the bottom line is
that you designed for a part that doesn't exist. period.

your mistake, not microchip's.

again, i appreciate your dilemma, and i hope you find a solution, but i think you are out of line blaming microchip
for a part that works just fine, exactly as it was intended to, and is being used by thousands every day with no
problems whatsoever.


david dunn

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