My oldest 8751 has a copyright year of 1980, and, IIRC, it was in '80 that Intel published a series of marketing posters which were, in fact enlarged photomicrographs of the layers of their then-popular chips, with indications of where certain features were located on the chip.

One story that went around quite a bit in the context of that Soviet cruise-missile controller chip that was an obvious copy of one of these popular CPU's, presumably the 80186, was that the Soviets created it using these posters.

I learned where the security bit in the 8751 was located, with enough precision to allow me to erase it by means of a precision stepper and a UV laser, much to the chagrin of some NSA fellows who insisted we use that in an encryption device they'd specified as a proposed replacement for DES encryptors commonly used in electronic funds transfers. They clearly wanted something easier for them to "crack."

After going to all that trouble, I also learned that there was a simple scheme using a little external hardware that enabled the code in an external ROM to access the "protected" code within the 8751. <sigh>

I lobbied for the MOT 68HC11 in that app, but they (NSA)wouldn't go for it.

RE