Hi Henk,

if I remember right, some time ago I read a question about 7851 in the Philips forum.
But the subject was, how can locked devices be reprogrammed. The answer was, never. It seems, that the lock bits can newer be erased also in windowed devices.
Maybe, they are made like fuses in old PLD devices, which are blowed by high current.
Please read the older Philips forum to find this guy.

But I think also, you save real money and time if you buy new CMOS (and Flash)devices.


Peter