How did studies of the crab nebula pin down the explanation of pulsars?

A pulsar is a neutron star that gives off pulses of radio waves. The Crab Nebula, which is one of millions of gas and dust clouds in space, was found to house a pulsar in the system as is the central object present. Astronomers observing the nebula noticed that it released pulses of radiation that span the electromagnetic spectrum, pulsing radio, gamma and xrays.