The history of the oscilloscope reaches back to the first recordings of waveforms with a galvanometer coupled to a mechanical drawing system in the second decade of the 19th century. The invention of the cathode ray tube and vacuum tubes allowed the development of oscilloscopes of the modern form. Vacuum-tube based oscilloscopes were critical to the development of radar during the Second World War, and development of electronic digital computers. The modern day digital oscilloscope is a consequence of multiple generations of development of the oscillograph, cathode-ray tubes, analog oscilloscopes, and digital electronics.

The earliest method of creating an image of a waveform was through a laborious and painstaking process of measuring the voltage or current of a spinning rotor at specific points around the axis of the rotor, and noting the measurements taken with a galvanometer. By slowly advancing around the rotor, a general standing wave can be drawn on graphing paper by recording the degrees of rotation and the meter strength at each position.

This process was first partially automated by Jules François Joubert [fr] with his step-by-step method of wave form measurement. This consisted of a special single-contact commutator attached to the shaft of a spinning rotor. The contact point could be moved around the rotor following a precise degree indicator scale and the output appearing on a galvanometer, to be hand-graphed by the technician. This process could only produce a very rough waveform approximation since it was formed over a period of several thousand wave cycles, but it was the first step in the science of waveform imaging.

The first automated oscillographs used a galvanometer to move a pen across a scroll or drum of paper, capturing wave patterns onto a continuously moving scroll. Due to the relatively high-frequency speed of the waveforms compared to the slow reaction time of the mechanical components, the waveform image was not drawn directly but instead built up over a period of time by combining small pieces of many different waveforms, to create an averaged shape.

The device known as the Hospitalier Ondograph was based on this method of wave form measurement. It automatically charged a capacitor from each 100th wave, and discharged the stored energy through a recording galvanometer, with each successive charge of the capacitor being taken from a point a little farther along the wave. (Such wave-form measurements were still averaged over many hundreds of wave cycles but were more accurate than hand-drawn oscillograms.)

In order to permit direct measurement of waveforms it was necessary for the recording device to use a very low-mass measurement system that can move with sufficient speed to match the motion of the actual waves being measured. This reduced the measurement device to a small mirror that could move at high speeds to match the waveform.

The term "oscillograph" was coined by André Blondel in 1893 to refer to his instrument based on the earlier-known mirror galvanometer but adapted to recording high-frequency oscillations. William Duddell also developed a similar instrument few years later.

To perform a waveform measurement, a photographic slide would be dropped past a window where the light beam emerges, or a continuous roll of motion picture film would be scrolled across the aperture to record the waveform over time. Although the measurements were much more precise than the built-up paper recorders, there was still room for improvement due to having to develop the exposed images before they could be examined.