On the design of easily testable sequential machines

In order to obtain a short fault-detection sequence for a sequential machine, the concept of an easily testable machine is introduced. Such a machine is one which possesses a minimal-length homogeneous distinguishing sequence and requires no transfer sequences in the fault-detection sequence. A design procedure is presented in which an arbitrary machine is embedded in an easily testable machine by adding input lines to the original machine. The procedure also derives a fault-detection sequence for the easily testable machine.