[1][2] For example, cell phones coming off of an assembly line may be given a final test in the same way as the individual chips were earlier tested.
Each cell phone under test is, briefly, the DUT.
For circuit boards, the DUT is often connected to the test equipment using a bed of nails tester of pogo pins.
The test equipment then applies power to the part, supplies stimulus signals, then measures and evaluates the resulting outputs from the device.
While packaged as a wafer, automatic test equipment (ATE) can connect to the individual units using a set of microscopic needles.