An oscilloscope, previously called an oscillograph and informally known as a
scope or o-scope, CRO (for cathode-ray oscilloscope), or DSO (for the more
modern digital storage oscilloscope), is a type of electronic test instrument
that graphically displays varying signal voltages, usually as a calibrated
two-dimensional plot of one or more signals as a function of time. The displayed
waveform can then be analyzed for properties such as amplitude, frequency, rise
time, time interval, distortion, and others.