The interval of the gliss corresponds to the D line being switched. D8 causes a two octave gliss, D7 - one octave, D6 - maj 3rd, D5 - maj 2nd, D4 - min 2nd, D3 - quarter tone. Because each voice glisses in a direction independent of other voices, the harmony will shift in a random direction but under a predictable interval. For example, say you two voices, C and G, creating a perfect 5th. Now, switching on D6 causes a major 3rd gliss up, down, or no change. The C can then go up to E, down to Ab, or stay on C. The G can go up to B, down to Eb, or stay on G. Thus we have 9 chords it could possibly shift to: EB, EG, EEb, CB, CG(no change), CEb, AbB, AbG, AbEb.
The synth can have 10 simultaneous stereo voices and the L and R channels also act independently, so a harmony with 20 moving voices is possible. Other intervals can also be glissed if the switches /are activated simultaneously. All of this makes for an interesting control scheme where the musician is only in control of the interval, but not the direction