On Thu, 26 Jul 2001 12:30:04 +0200, you wrote:

>> >Very simple:  Allow me to disable ICSP reads no matter what, and =
allow me
>> to
>> >disable internal reads of the flash memory, but allow internal flash =
to
>be
>> >re-written.
>
>Bad idea, how would you VERIFY?
Simple - you have a 'read enable' bit in the hardware, which is set
when a cell is erased, and cleared when the address register is
written to. This allows you to erase, write and read back a location
until it verifies OK, but then doesn't allow any 1-bit-at-a-time type
attack. Should use minimal silicon - one set/reset latch and a few
gates


=20

--
http://www.piclist.com hint: PICList Posts must start with ONE topic:
[PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads