[CCWoody]

A idiot proof system that worked under any foul up or failure of any individual component. ~ wirestripper

Yeah, right! You obviously needed to find better idiots. Besides, if you truly had an idiot proof system, only an idiot would want to use it. hehehe!

The memory was permanent, but could be modified if you had the program to do it. ~ wirestripper

Most PLC's or ASICs (Application Specific IC's) that I have built (Opps, there goes my engineering expertise) use either a EEPROM (Electrically erasable programable read only memory) or a UV erase type. I was even part of a group once who made chips that were put onto the shuttle, though, I think none of them were the PLC's.

Woody.

[Cold Heat]

use either a EEPROM (Electrically erasable programable read only memory)

Yes, EEprom and PROM,s were used. However, a basic computer that was off the shelf at the time could do the same. It was much too expensive compared to the 500 dollar price of a PLC.

[Zavien Doombringer]

peel back the foil wrapper ,expose litle window and "poof" no more data!