Atari Game Tools: Atari STE game engine - Parallax Regions
This is a straightforward example of 4 parallax scrolling regions at 320x272 with a bunch of sprites on top, on Atari STE, using the AGT engine.
Everything is drawn in 4 bitplanes / 16 colours, no palette trickery involved.
Runs at 50Hz with a decent amount of CPU to spare.
While this example is just a 'rolling' demo, this technique is fully usable in horizontal scrolling games with a configurable number of parallax regions.