digital electronics is a part of the electronica that is responsible for electronic systems in which information is encoded in only two states. Those statements can be called “true” or “false”, or more commonly 1 and 0, referring to an electronic circuit that is (1 – True) tension voltage is no tension or voltage (0 – False) . Electronically are assigned to each voltage or voltage range specified, which are called logic levels, typically in any digital signal. Usually the values of voltage in electronic circuits ranging from 1.5, 3, 5, 9 and 18 volts depending on the application, for example, in a conventional transistor voltage stresses are usually 5 to 12 Volts As used in computer hard disks IDE. Boolean algebras Boolean algebra believe that bears his name in the first quarter of the nineteenth century.