Three.
1. Main volume
2. Expression - frequently either does rotary/dry/chorus or a 3 or 4 range sound morph with (usually) lead sound at toe-down
3. Wah
There was a fourth, but it got demoted to a big knob - still tweakable with a toe, but generally a set and forget at 50% for less frequent tweakage....
There are also two faders and four switches on MIDI and 7 switches via FC6 stand-in switches and FM9 pedal jacks that all do various things....
FM9 Pedals
1. Amp boost via CS1
2. Various, usually a drive via CS2 or a channel toggle for the lead amp
3. Various, usually a drive via CS3 or a channel toggle for the lead amp
FC6 switches
1. View toggle / Preset +1
2. View Toggle / Preset -1
3. Momentary delay runaway
4. Momentary "Dramamine" flange
MIDI switches
1. Tap tempo
2. Momentary Expression - usually a 20dB mid boost before the amp(s)
3. Momentary Expression - usually rotary speed
4. Latching Expression - usually rotary speed
MIDI faders
1. F/M compensation - helps somewhat un-FUBAR your tone if too middy or too boomy/sizzly
2. Delay wetness