Abstract: An inventive semiconductor device includes a semiconductor layer, a source region provided in a surface layer portion of the semiconductor layer, a drain region provided in the surface of the semiconductor layer in spaced relation from the source region, a gate insulation film provided in opposed relation to a portion of the surface of the semiconductor layer present between the source region and the drain region, a gate electrode provided on the gate insulation film, and a drain-gate isolation portion provided between the drain region and the gate insulation film for isolating the drain region and the gate insulation film from each other in non-contact relation.

Abstract: A semiconductor memory incorporates a protecting circuit which causes data, stored in a memory portion, to be output by executing a key canceling sequence from an external apparatus. The data stored in the memory are output only when a key canceling signal is input to the protecting circuit. Thus the data are not output only by inputting an address signal and a reading signal to the memory apparatus. As a result, it is impossible to find out the contents of the program stored in the memory portion without inputting the key canceling signal.