thumb|300px|right|Watch this video to hear what a typical 45 sounds like. Video by WABC77 (YouTube Account)45 RPM. The poly-vinyl chloride 45 rpm microgroove single was invented by RCA in 1948. It has one song per side, and was in a "format war" in the late 1940s with the LP, invented by Columbia Records. Both "won" and replaced the shellac 78 RPM record. The 45 rpm single along with the LP got eliminated by the CD, and cassette in the late 80s, yet enjoyed a re-surge in popularity as of 2007.