Introduction: Will understand the structural composition of logistic circuit, function, use through reading circuit manual, also can pass read truth table, between understanding output and input " be " or " blame " logistic relation, master each logistic function of unit module. Digital circuit is the circuit that realizes certain and logistic function, call logistic circuitry, call switch circuitry again. The transistor in this kind of circuit works commonly in switch condition. Digital circuit can be formed by discrete element (like inverter, self-excitation much resonance swings implement etc) , but great majority is now form by integrated circuit (be like with door circuit, or door circuit) . Want to understand digital circuit plan, all sorts of logistic symbols that the basic knowledge; that should master circuit of a few numbers above all is unit of logic of understanding binary system next and output, input concerns; Return the knowledge that should master a few logistic algebra next. Had these basic knowledge, also laid good foundation to understand digital circuit to pursue. Digital circuit knows graph method to be as follows: One, " it is dispute blame sees logic " the structural composition that understands logistic circuit through reading circuit manual, function, utility, also can pass read truth table, between understanding output and input " be " or " blame " logistic relation, master each logistic function of unit module. 2, yuan function of parts of an apparatus sees the integrated circuit that often makes appliance has all sorts of logistic functions in circuit of the number that cite a base, such meetings make whole circuit simpler, reliable. But also bring certain difficulty to remember a picture. Because cannot see integrated circuit is in-house,yuan of parts of an apparatus and circuit comprise a circumstance, can see a lot of external bringing only foot, these bring a foot to have each effect each, these bringing foot and exterior and other yuan of parts of an apparatus or circuit join, in order to realize particular function. Actually a lot of moment do not need to know circuit of integrated circuit interior comprises a circumstance, need to understand only exterior the function that cites a base each can. Integrated circuit brings crural function to try to make clear with the character each, if literal specification or parameter did not give out in circuit, should consult concerned manual, know the logistic function with agglomerate collect and the effect that cite a base each. To a few commonly used integrated circuit, be like commonly used operation amplifier LM324, 4 2 inputs and circuit of the 74LS00 that be not the door, 555 time base, the reader should remember each bring crural function, this is helped somewhat to graph of fast, accurate knowledge. 3, the function is decomposed see circuit of module logarithm word can flow to a system to be divided into by signal a certain number of functional module, every module fulfils relatively independent function, undertake to module each other makes condition analysis, can list when necessary truth table of logic of the input of each module, output. 4, rise integratedly see whole join each module, analytic circuit is over from what input output full employment process, can draw concerned job weaveform to pursue when necessary, in order to help the analysis of logistic to circuit function, understanding. CNC Milling