He was a solid metronome with atomic clock precision that played so loud he cost early Zeppelin many a gig at many-a-pub for waking the "old folk", and did it with ONLY one tom-tom that showed how modest he truly was.
That beat is actually very complex, falling in between the typical 1/4, 1/8, 1/16th, etc,.. fractions of conventional rhythm, in fact, his most impressive stuff were his off-key, "out of time", beats rather than his solos.