The structure of a screen for protect of the memory cells of an ultraviolet radiation and a read-only memory erasing provided with such a structure.

摘要

The object of the invention is a mechanism for changing the functionality of a finished controller controlling the operation of a device is introduced. & br / & the mechanism is programmed to generate signals having the logic levels, and applied to the input of a combinational logic circuit for the implementation of the finished (31) in order to operate with a predetermined number of waiting states (generally 1, 2 or 3) according to the programming of the mechanism. The programming is carried out after the manufacture of the piece, but before the dispatch to a customer who, at its reception, the program the eprom (35) of the usual manner. The eprom programmed can then be withdrawn and then reprogrammed, without being affected, the programming (uprom 43) defining the number of states of the waiting generated. & br / the invention is applicable to the electrically erasable programmable read-only memories and