The Little Phatty is an analogue monophonic synth with 2 oscillators and the classic Moog filter.
I won’t get into the detailed specifications, but let’s just say that all the usual basic functions are there, plus the very useful Overload knob, that helps you create a most musical and warm overdrive. It’s a 100% analog signal path, but you get some of the comfort a 2008 keyboardist might expect : MIDI and patch storage obviously (it was before Moog Music got into the unhealthy retro fetishism that produced the Voyager Old School), but also a very useful auto-calibration routine.