Yes, the chord-like sound is fast arpeggiator, with default arpg. settings. Then chords for arpeggiator were sequenced on one track (track 2). The sound is 1 oscilator with relatively short decay, and signal run slightly through delay (to achieve falling sound of each chord hits) - normally on 8-bit computer I’d do this using two track (second one for silent repetitions).
Lead is done also on 1 osc with modulated PWM by LFO. The problem I had here is that A4 sequencer didn’t record pitch bend (even if CC&NRPN receive set to ON) and I was too lazy to do note slides ;).