How can I add chip tone instruments into Anvil Studio?
You can't add any new instruments to MIDI, no matter what program you use. MIDI has its own set of instruments and you cannot change it.
Almost.
MIDI doesn't have its own instruments. The instruments are in a file on the computer.
When a computer plays MIDI, it runs it through a VSTi that interprets and plays the notes. However, because .midi files are always played by a standard VSTi built into the computer (for Windows, this is the MS Wavetable Synth), .midi files themselves always use those default instruments.
Many MIDI-editing programs allow you to set up a VSTi synth in your project so that your music can be played by other instruments. Perhaps you can find a good chiptone VSTi online?
Like minmay said, an actual
MIDI file cannot include the instruments from that synth. The way you make MIDI use different instruments is by using MIDI software that allows you to select a synth. But the program you use will either need to have its own special native save format that isn't MIDI, or it will need to be able to render your file to mp3/ogg.
If all the program can do is compose MIDI, play MIDI, and save to MIDI format (and I believe this is the case with Anvil), you're stuck with the standard VSTi.
EDIT: Yup, Anvil Studio cannot load third-party VSTi unless you purchase the
Pro Mix accessory.