The ROM device has a memory array including memory cells formed by an access element and a data storage element; a high voltage column decoder stage; a high voltage row decoder stage; an analog stage; and a writing stage, wherein the data storage elements are electrically non-programmable and non-modifiable. The memory array is formed by memory cells having a first logic state and by memory cells having a second logic state. The data storage element of the memory cells having the first logic state is formed by a continuous conductive path uninterruptedly connecting the access transistor to the respective bit line, the data storage element of the memory cells having the second logic state is formed by a region of dielectric material insulating the access transistor from the respective bit line.