A Look @ voice structure:

The SQ80 can hold 40 patches internally and 80 on a RAM cartridge giving 120 locations in all. Each patch consists of 3 DCOs (Digitally Controlled Oscillator), 3 LFOs (Low frequency Oscillators), 4 Envelope Generators, 4 Digitally Controlled Amplifiers (One for each DCO, and one for the final output ... with pan), and a VCF (Voltage controlled analog filter with variable "Q"). Each DCO, LFO, and DCA has two modulation inputs. There is even an analog control voltage input jack in the back that can be used! DCO 1 can even modulate DCO 2 giving a kind of "ring modulator" effect [it is actually Amplitude Modulation but it sounds close to Ring Modulation] and DCO 2 can sync to DCO 1 which can be used as a sort of "Pulse width modulation" effect ... but that can be used on any of the 75 waveforms. The 75 waveforms for the most part are quite good from a musical and sound design point of view. If you needed more oscillators ... or one going through the filter and one not you could layer two patches... but then you would only have 4 notes.
The modulation sources are LFOs (three) which can do triangle, square, and sawtooth wave, along with a "random" wave, 4 EGs [Envelope Generators or ADSR Attack Decay Sustain Release ... except between key on and sustain there are 3 points not just two, and there is a Second Release (simulated reverb) option as part of the release)], Keyboard Velocity (both linear and exponential), keyboard scaling, the mod wheel, pedal input, any assigned MIDI controller, and channel or key (poly) aftertouch. The LFO's can even modulate themselves (LFO1 is an valid modulator for LFO1 and so on). Modulator values can be assigned positive or negative multipliers so very complex modulation is possible.