Obsolete data controller from defunct company uses this Philips ucontroller. Units are failing and customer has the option of either throwing out all his infrastructure when these units fail and spending $$$$ to replace everything, or burning new controller ICs as units fail.
It looks like the P87C750 comes with a 16-byte encryption table, optionally used to encrypt the contents of program memory.
The only way, it seems, to know if the memory contents has been encrypted is to read the contents and see if it contains legible code.
Is there another means to know if the memory contents have been encrypted?