The Roland CR-78 CompuRhythm is considered a classic analog rhythm machine as the first of its kind to use integrated circuits. An important development in the history of drum machines. This allowed for the introduction of a Programmer section, which provided 4 programmable memory locations for pattern storage. Now users could program and store their own drum patterns, as well as adjust tempo, accents, and fade ins and outs. Individual mute controls for each of the four voices were featured on the front panel, allowing the user to create breakdowns.
Although primitive by today's standards, the CR-78 represented an important advance in drum machine technology at the time, 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, Duchess by Genesis, and "In the Air Tonight" by Phil Collins.
The CR-78 uses analog drum voices, which sound very little like real percussion instruments. The unit also incorporates an NEC 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 at the time of its introduction was that in addition to offering 34 preset rhythms, it provided four programmable memory locations for storing patterns created by the user. These can be created by using step programming with the WS-1 box, which was available as an optional extra. The four user patterns are stored in RAM memory; when the CR78 is switched off, the contents of the RAM are maintained by a NiCd rechargeable battery.
The CR-78's front panel allows the user to customize the preset rhythms by altering the volume balance between bass and treble sounds, canceling some sounds altogether, and adding "metallic beat" (three filtered square waves that create a distinctive chime timbre). 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 is provided on the front panel, with only an analog knob for tempo control. However, the CR-78 accepts 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 are 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, and "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.
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 consist of bass drum, snare drum, rim shot, hi-hat, cymbal, maracas, claves, cowbell, high bongo, low bongo, low conga, tambourine, guiro, and "metallic beat" (an accent that could be overlaid on the hi-hat voice). The CR-78 has an accent control, which increases the loudness of certain steps in a pattern.
There are four patterns named "Rock" and two named "Disco". Other patterns are named "Waltz", "Shuffle", "Slow Rock", "Swing", "Foxtrot", "Tango", "Boogie", "Enka", "Bossa Nova", "Samba", "Mambo", "Chacha", "Beguine" and "Rhumba". Each pattern is available in two variations, labelled "A" and "B". It is 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.
The CR-78 could also be programmed using the standard TS-1 Memory Write Switch or the rather hard-to-find WS-1 programming switch. They allow for pattern programming via a step-programming method similar to that on the TR-808. You program 2 bar patterns one voice at a time and up to 4 voices can be simultaneously played. Each of the four voices can be independently muted from the front-panel allowing for building up and breaking down your rhythm patterns. Patterns can also be set to fade-in/out. User patterns are stored to battery-backed memory.