Sorry for OT, but I in big trouble!
From time to time my devices with above mentioned processors corrupt content of internal program memory. Does anyone see this behavior od 80C51ED2?
Dozsa Gyoergy
P.S. Keil C51 user since '91
already answered: (which do not hold the uC in reset during power down)
You keep repeating this without exlaining why it would matter.
Even the magnificent Jack Sprat can not tell what a uC will do when outside the Vcc limits and not in reset.
I'm sorry to disappoint you, but I can.