
468 Model-Based Testing for Embedded Systems
16.4.2 Passive testing and verification of clocked circuits
At the time of this writing, the vast majority of digital chips are clocked circuits. Such
circuits consist of several mutually dependent functional units (e.g., in a microprocessor this
includes the register file, the adder, multiplier, memory management, instruction decoder,
and so on). Their communication is carefully synchronized (this style of chip is thus called
synchronous). Ideally, the synchronicity is driven by a chip-wide clock that is usually a
square-wave electrical signal. Operations as well as data movements through gates only
occur ...