The Poly800 series (i.e. Poly-800, EX-800, Poly-800II) demonstrates the cost effectiveness of digital vs. analog, being one of the least expensive synthesizers of its era. The analog side is sparse with only a shared filter for all voices, but the digital side boasts dedicated amplifier envelope generators for each oscillator and a sequencer.
The Poly800 series (i.e. Poly-800, EX-800, Poly-800II) starts with a simple "square" waveform (along with noise). At first glance on the front panel, it appears the Poly800 also has a saw waveform, but technically the "WAVEFORM" setting only controls the relative volumes (i.e. flat or decreasing) of the harmonics (16'/8'/4'/2'), allowing a crude version of additive synthesis, using square waves (vs. the typical sine wave harmonics). This concept may be the start of the additive engine later built into the DSS-1. The "square" waveform actually looks more like a saw wave at low octaves transitioning to a square wave as the octaves increase (see pics). The Poly800 series can have 1 or 2 oscillators per voice (8 or 4 notes polyphony, respectively).
All voices are routed through a single Korg NJM2069 4 pole filter. Incidently, the filter chip is capable of 2 pole output, but access isn't granted via the user interface (or wiring). Filter bandwidth tops out at a respectible 25kHz and is 2kHz when cutoff is set to its mid-point (see pics). Two levels of key scaling are provided, the highest level approximately doubling the filter frequency with each octave.
The Poly800 series synths implement 3 dedicated 6 element (ADBSSR) EGs (envelope generators), assigned to each of the two oscillators and the filter. Dedicated oscillator EGs implies pre-filter amplifiers, similar to the Ensoniq ESQ-1 family.
An LFO is routed to oscillators and filter. The waveform isn't programmable, but it does have delay. All keyboard models (Poly800 and Poly800II) offer a joystick to control both LFO destinations and bend.
The Poly800 series synths also have a step sequencer, while the keyboard versions add chord memory too.
The Poly800 and EX-800 have stereo chorus, while the Poly800II has a stereo delay (with dedicated LFO), similar to the DW/EX-8000.
Korg 2069 filter