See Oscillator Waveforms

How it works:
This examples generates many different waveforms ansd displays them using the oscilloscope. Uncheck Auto to stop automatic capture. Hit "Capture" to record and display waveforms. Select a waveform using radio buttons at the bottom. Waveforms include:

Sawtooth - Shaped like the edge of a saw. Contains all harmonics. At negative frequency, it slopes backwards.
Sine - Single sine wave.
Triangle - Looks like a sine wave but with pointy corners. Contains all even harmonics.
Square - Alternates between -1 and +1. Contains all odd harmonics.
RedNoise - Linear ramps between random values.

Note that the waveforms with the "BL" suffix are band-limited. Sweep the frequency up and down and compare their smooth sound with the non-band-limited versions. Band limiting eliminates high frequency partials above the Nyquist rate which cause aliasing.

Visit the JSyn or SoftSynth home pages.