Hi DomDevl,
I used a program called Famitracker to make these songs. Another tracker program you may consider is called Deflemask, which allows you to make songs in the style of a bunch of consoles like NES and Genesis.
There is a bit of a learning curve to using these, so if you are already familiar with working in a DAW, another option for you would be the C700 vst. You can use this one to make SNES style tunes as well.
All 3 are free, but I suggest looking these up on Youtube and getting an idea of what the work flow is like before diving in.
Best of luck to you! :D
-Bert