The triangle channel is one octave lower. Pulse and noise channels have 16 volume levels. Triangle and digital channels have no volume control. The triangle waveform is synthesized by modulating 16 volume steps, hence the lack of volume control and subtle metallic resonance-type sound noticable at low frequencies. Noise channel has 4-bit frequency control, and is capable of producing 16 frequencies.
Noise channel has a special 'looped noise' setting that allows it to produce a metallic sound.
Digital channel's DMA method allows access to only 16k of sample data, but by using external bankswitching hardware you can overcome this limitation. Pulse channels have a built-in primitive volume envelope function. Dance of the Sugarplum Fairies by Tchaikovsky, covered by Doppelganger, code by Doppelganger. Nuclear Power medly by Mankeli, code by Bananmos. Resident Koopa .IT format by Lysander Lapine.