REV2 is perfect for emulating this patch. It is harmonica, not sax, although some tracks on the ost do feature sax. I recon you are looking for the famous lead patch from the main theme and tears in rain.
I usually do this on Prophet 10, but REV2 has that brassy filter, as well as 2 pole mode that makes it slightly closer to CS-80.
What it is is two oscillator layers:
- square with pwm
- CS 80 shark fin saw - you can mod shape of the saw or go for saw-triangle osc. Normal saw will do too, these are really nuances.
Vangelis has used this patch in many other pieces, altering the envelope and modulation, but the core sound is the same - find the right blend between these two sound sources, you can have fairly short envelope attack to be able to play harmonica - style stuff over string machine layer like Blade Runner Blues does, or increase attack to have it almost as a pad. What makes this sound so special is also the manner of playing and the poly aftertouch of the CS-80, but you can get close on REV2. If you have a nice chorus and reverb pedals or plugins, ofc, these are essential part to that vibe. I will post a video soon showing this patch, will attach it here too.