  The paper is concerned with defining the electrical signals and their models.
The delays are discussed, the asynchronous automata - which are the models of
the asynchronous circuits - and the examples of the clock generator and of the
R-S latch are given. We write the equations of the asynchronous automata, which
combine the pure delay model and the inertial delay model; the simple gate
model and the complex gate model; the fixed, bounded and unbounded delay model.
We give the solutions of these equations, which are written on R->{0,1}
functions, where R is the time set. The connection between the real time and
the discrete time is discussed. The stability, the fundamental mode of
operation, the combinational automata, the semi-modularity are defined and
characterized. Some connections are suggested with the linear time and the
branching time temporal logic of the propositions.
