Disco — the late-70s dance-floor groove reduced to its machine: kick on every beat, snare on 2 and 4, hi-hat closed on the beat and open on every "and" ("boom-tss"), and the bass playing **octaves in straight eighths** — low root on the beat, high root on the "and" — for the whole bar (Chic, Bee Gees, the Salsoul Orchestra). Keyboards and strings stab on the "and"s on top of the open hat; the guitar scratches sixteenths (down, mute, up, mute) so the top of the texture is a continuous hiss.
The harmony moves between two minor sevenths a fourth apart, which is often all a disco verse does.
Listen for the three layers of the off-beat: open hat, bass octave and keyboard stab all landing on the "and" while the kick holds the beat. That interlock is why four-on-the-floor sounds like dancing rather than marching. Practice: bass alone with the kick, octaves dead even — the high note must not be louder than the low one. Then add the stabs. Compare motown-bass (the same drum pattern with a melodic bass) and reggae-steppers, which opens the hat on the off-beats at half the tempo.