The Wurlitzer Swingin’ Rhythm was a drum machine that was released as an accessory to Wurlitzer organs. There are two versions: a standalone unit, and an internal version that was built-in to certain Wurlitzer organ models. It was intended to supersede the earlier Side Man drum machine.

The standalone Swingin’ Rhythm was small enough to fit on top of Wurlitzer organs. This can be attributed to the internal electronics, which featured a densely populated integrated circuit topology. According to the patent for the Swingin’ Rhythm’s electronics (3,585,891, granted in 1971), the ability to put the drum machine on top of the organ was an explicit design objective:

Since electronic organs and pianos are customarily designed for compactness, a relatively large generator is not only inconvenient but also unsightly. Accordingly, one object of this invention is to provide an electronic rhythm generator which can be packaged in a relatively small housing that will be inconspicuous when used with a small electronic organ and which will fit in the limited space that is available on top of the smallest electronic organ within easy reach of the musician’s hand.

The Swingin’ Rhythm’s integrated circuit topology was emphasized in marketing materials. As written on the back cover of Swingin’ Rhythm / Glenn Derringer, a 1968 promotional record released by Wurlitzer:

This electronic miracle of sound…the wide diversity of this orchestral unit…is produced through the use of integrated circuits. Pioneer in the use of integrated circuits in musical instruments, Wurlitzer now offers the most authentic and most exciting rhythm effects ever, to accompany whatever instrument is being played!

Swingin’ Rhythm / Glenn Derringer was released to demonstrate the Swingin’ Rhythm’s features. Derringer was a musical prodigy who started his career in the 1950s performing on television programs like The Ed Sullivan Show, The Bob Hope Show, and Stage Show, a CBS variety show hosted by Tommy and Jimmy Dorsey. (In the Stage Show appearance, Elvis was Derringer’s opening act.) In the 1960s, Derringer was closely associated with Wurlitzer, and frequently recorded organ demos for the company. In Swingin’ Rhythm, Derringer plays fourteen songs on an unnamed Wurlitzer organ, using the Swingin’ Rhythm drum machine as accompaniment. Derringer’s settings on the Swingin’ Rhythm were included in the track listing on the back cover, so that home organists could play along. The album can be listened to here.