A remix of Wily Stage 3-4 from Mega Man 3 using the Konami VRC6 and standard NES/Famicom channels. The Konami VRC6 was a chip that, among other things, gave three additional sound channels (two pulse channels and one sawtooth channel). The pulse channels allowed the composer to choose between 8 duty cycles, as opposed to the standard NES/Famicom channels which only had four (one of which is basically an inverted version of another, so only three of them are useful). Unfortunately, hardware differences between Japan's Famicom and the USA's NES made it impossible to use extended audio on the NES (at least not without some hardware modding). Google it if you want more information.
Music made with FamiTracker.