Description of digital systems by various construction schemes

The article discusses ways of describing digital systems with various schemes, provides a comparative characteristic of these schemes, indicates the advantages and disadvantages of different schemes. The four schemes for constructing digital systems described in the article are equivalent, since with the same input signal, the output signal for all circuits will be the same, although different signals will circulate inside these circuits. To build adaptive digital systems, preference should be given to state-space circuits, since in them it is easier to adjust the parameters of the digital system. When choosing between serial and parallel circuits, preference should be given to the parallel circuit if the coefficients in it are valid. With complex coefficients, the implementation of the parallel scheme becomes more complicated, therefore, in this case, one should choose a sequential scheme in the state space, all the coefficients are real.