Most TMS devices produce a monophasic or biphasic standard pulse that was originally modelled on the narrow (50 ms) electrical pulses commonly used to stimulate large diameter fibres in peripheral nerve. The stimulators allow users to change the amplitude of the stimulus but not the waveform shape or polarity. However, new devices are appearing that allow much more flexible control of the pulse waveform as well as the ability to generate high frequency repetitive stimulation with monophasic as well as biphasic waveforms. Such innovations allow us to probe the characteristics of cortical neurons in much more detail, and improve targeting of different neural populations. The effects are evident in both the MEP and TEP (TMS evoked EEG potentials). For example, the relationship between threshold and pulse duration allows estimation of neural strength-duration time constants. These differ between different types of neuron and are changed by disease (ALS) and anti-epileptic drug therapy. The different time constants of excitatory and inhibitory neurons mean that waveform can be manipulated to improve, for example, short-interval intracortical inhibition (SICI). Repetitive monophasic stimulation can be more effective than the usual biphasic stimulation, and the same stimulator can be used for regular rTMS as well as quadrupulse TMS, which until now has required four separate TMS devices to be linked together. After 40 years of the same TMS, it is surely time to update our machines.