Reply 100 of 110, by Scali
Rasterbars in 64 colours in 640x350 sounds nice 😀
A 286 should have no problems with that. An 8088 at 4.77 MHz might show a bit of noise on the left side of the screen if you implement it with polling (even the original CGADEMO suffered from that, and 350 lines require 75% faster processing than 200 lines).
Cycle-counting would work, but is far more difficult, and requires a fixed platform (so only one type of CPU, chipset and EGA card, much like 8088 MPH).
Combining a mod player with time-critical effects like rasterbars is going to be difficult, unless you synchronize the two. Eg, output one sample at every scanline. You have 350 visible scanlines, but also a bunch of invisible ones. CGA/EGA for example has 262 scanlines in 200-line mode, so you'd get 60*262 = ~15.7 KHz if you do a sample per scanline.
In 350 line mode you probably have around 400 total scanlines, so you'd get around 60*400 = 24 KHz that way.