Here's the original Lemmings soundtrack from the Archimedes version (i.e. the machine under discussion). The game probably ran with 1MiB RAM, certainly it would have worked with 2MiB: https://www.youtube.com/watch?v=QwXthGJfHLc

That is the sound from the internal speaker. The computers were also popular for MIDI control, even being chosen by professionals for this, though I can't find a video.