The Roland Rhythm 77 drum machine was Roland's first product (formerly Ace electronics) - released in 1972. It is actually an updated and relabelled Rhythm Ace FR-8L
It was one of a trio of drum machines released by Roland that year, offering features intermediate between those of Rhythm 33 (TR-33) and Rhythm 55 (TR-55).
It comes in a flat wooden case with a metal base and has a holding for scorebooks - was dedicated to put at top of an organ for rhythm accompaniment.