The Roland CompuRhythm CR-78 is a drum machine launched in 1978.

Although primitive by today's standards, the CR-78 represented an important advance in drum machine technology at the time, in particular by allowing users to program and store their own drum patterns. The wood effect cabinet and preset rhythms of the CR-78 such as Waltz, Bossa Nova and Rhumba suggest that it was seen by its designers as primarily an accompaniment for an electric organ, but the CR-78 became one of the favorite instruments of Pop and electronic musicians in the late 1970s and early 1980s. Famous songs that make prominent use of the Roland CR-78 include "Vienna" by Ultravox, "Heart of Glass" by Blondie and "In the Air Tonight" by Phil Collins.

The machine and its controls
The CR-78 used analog drum voices, which sounded very little like real percussion instruments, but they instead had their own distinctive sounds. The unit also incorporated an early Intel microprocessor to provide digital control of its functions.

Previous Roland drum machines had offered only a selection of preset rhythms. The CR-78's key new feature was that in addition to offering 34 preset rhythms, it provided four programmable memory locations for storing patterns created by the user. These could be created by using step programming with the WS-1 box, which was available as an optional extra. The four user patterns were stored in RAM memory; when the CR78 was switched off, the contents of the RAM was maintained by a NiCd rechargeable battery.

The CR-78's front panel allowed the user to customize the preset rhythms by altering the volume balance between bass and treble sounds, canceling some sounds altogether, and adding ring modulation ("metallic beat") to the cymbal sounds. Many of the preset rhythms have a memorable character, and the ability to manipulate them further made the CR-78 a versatile instrument.

No digital control of tempo was provided on the front panel, with only an analog knob for the function. However, the CR-78 would also accept an external V-trig clock, allowing a control voltage to be fed in from another device such as a music sequencer.

A selection of preset fills and rhythm variations were also available, either to trigger manually, or automatically every 2, 4, 8 or 16 bars. Some of these fills were used in synth-pop songs such as "Enola Gay" by Orchestral Manoeuvres in the Dark, "Underpass" by John Foxx.

Roland also produced a simpler drum machine, the CompuRhythm CR-68. This was essentially the same as the CR-78, but without programmable patterns or the ability to fade drum sounds in and out. At the same time Roland also sold the TR-66, a smaller unit which offered fewer preset rhythms and no programmability.

Sounds and rhythms
The CR-78's built-in rhythm sounds were a further development of those available on the earlier Roland Rhythm 33, 55 and 77 machines.

The analog percussion voices consisted of bass drum, snare drum, rim shot, hi-hat, cymbal, maracas, claves, cowbell, high bongo, low bongo, low conga, tambourine, guiro, and "metallic beat" (a ring modulated accent that could be overlaid on the hi-hat voice). The CR-78 had an accent control, which increased the loudness of certain steps in a pattern.

The rhythm patterns were Rock 1, Rock 2, Rock 3, Rock 4, Disco 1 and Disco 2 (all available in 'A' or 'B' variations); Waltz, Shuffle, Slow Rock, Swing, Foxtrot, Tango, Boogie, Enka, Bossa Nova, Samba, Mambo and Chacha, Beguine and Rhumba. It was possible to select more than one rhythm at a time, and also mute drum sounds from a pattern using the balance knob and dedicated cancel buttons.

Notable recordings
Ultravox — "Vienna"
Landscape — "From the Tea-rooms of Mars .... to the Hell-holes of Uranus"
John Foxx — "Burning Car"
Blondie — "Heart of Glass", "Atomic"
Gary Numan — "Remind Me To Smile", "On Broadway (live)"
Genesis — "Duchess" and "Me And Sarah Jane"
Hall & Oates — "Kiss On My List" and "I Can't Go For That (No Can Do)"
Orchestral Manoeuvres in the Dark — "Enola Gay"
Phil Collins — "In The Air Tonight"
Roxy Music — "Same Old Scene"
Modest Mouse — "Missed the Boat"
Maze feat. Frankie Beverly — "Joy and Pain"