to follow or endeavor to follow as a model or example: to imitate an author's style; to imitate an older brother. to mimic; impersonate: The students imitated the teacher behind her back. to make a copy of; reproduce closely. to have or assume the appearance of; simulate; resemble.
The input device might be a keyboard, the output device might be a monitor, a communication device might be a modem, a secondary storage device might be disk drive, and the processing devices include central processing unit (CPU) and main memory.
The DAC output is one input to a comparator, with the other being the analog signal to be digitized. This input signal is usually pre-conditioned by a sample-and-hold (also called a track/store) amplifier. The S/H amp contains a switch and a capacitor that continuously charges/discharges to the input voltage.