Purchase Midines by wayfar from their website (see Resources). Midines is a cartridge which allows an outside MIDI source to control the five synthesizers built into the NES hardware. The Midines cartridge is the only one of its kind.
Set up your NES for optimal performance with Midines. Use a power supply of 1000mA or greater and insert a game controller into port 1 of your NES. Turn your NES system on.
Insert the Midines cartridge into your NES system as you would a normal game cartridge.
Connect the MIDI out port of your MIDI device or sequencer to the Midines' MIDI DIN port. The Midnes can process data from a single MIDI controller, a multi-channel MIDI sequencer or the MIDI out port of your computer.
Set up the Midines MIDI options by selecting Mode. Press "Select" on the game controller to toggle between Mode 1 and Mode 2 on the Midines interface. Mode 1 provides a graphic interface but results in inferior sound quality. Use Mode 1 to change the MIDI channels (1-5) associated with the five audio synthesizers built into the NES. Press the "up" and "down" buttons to select a synthesizer and "left" and "right" to change MIDI channels. Mode 2 has no graphic interface but provides a cleaner sound. It is best to set up your MIDI channels in Mode 1 then press "Select" to switch to Mode 2 for playback.