Roland CR-78 (1978–1981)

A push-button box with a microprocessor inside and four slots for your own rhythms. It put a computer in the drummer's chair.

Overview

The Roland CR-78 CompuRhythm is a desktop drum machine built around a real microprocessor. That is what separates it from the preset boxes that came before. Roland introduced it in 1978 and built it until 1981. The earlier organ rhythm units could never let a musician write a pattern and get it back later. This one could. The "CR" stands for CompuRhythm, a name Roland tied directly to the internal computer. Owners describe it as an analog rhythm machine with a digital brain - the sounds are analog circuits, but a resident computer running stored programs handles the sequencing.

The service documentation is unusually explicit about the architecture. It describes the CR-78 as "a computerized rhythm machine whose rhythms are controlled by the resident computer through internally stored programs." The central chip is a µPD8048C-015, an 8048-family microcontroller. The manual warns that there are several versions of the 8048 and each carries an exclusive resident program, so a replacement must be the C-015 part specifically. Alongside it sit an AM2708P-023 ROM and a µPD5101C-E RAM. It really is a small computer with drum voices hanging off it.

What that buys the player is programmability. The CR-78 has 34 built-in preset rhythms: Rock 1 through 4, Disco 1 and 2, Waltz, Shuffle, Slow Rock, Swing, Fox Trot, Tango, Boogie, and Enka. On top of the presets sit four programmable memory locations, each pattern spanning two measures with support for four independent tracks. Two measures is not a lot of memory. The survival-guide literature is blunt that writing a rhythm in with the step selector has to be done twice, because the machine only holds two measures' worth. But in 1978 the ability to store anything at all was the point.

It is a compact desktop unit. Sources describe the housing as a sturdy metal chassis suited to studio use, with colour-coded knobs laid out for programming. Reportedly it measures roughly 300 mm wide by 280 mm deep by 205 mm tall and weighs around 5.5 kg. Those are single-source figures, so treat them as approximate. The front panel is a push-button matrix, and the whole thing looks like lab equipment that happens to make drum sounds.

Key Features

µPD8048C-015 Microprocessor and Resident Program

The 8048 is the reason the CR-78 exists in the form it does. The service notes describe the power-on sequence in detail. Two oscillators start when power is applied: a master oscillator that sets tempo across a 5 Hz to 100 Hz range, and a clock generator that produces timing pulses for the 8048 on each step cycle. The computer scans the switch matrix continuously, even while stopped, so a pattern fires the instant START/STOP is pressed. During playback it scans once per measure, which means a switch change made mid-measure takes effect on the next one. The exception is the CANCEL VOICE function, which is scanned every cycle so an unwanted voice drops out immediately.

Four Programmable Patterns, Two Measures Deep

Four user memory locations, each two measures long with four independent tracks. That is the entire user-programmable capacity, and it is small. The CR-78 is not a sequencer in any modern sense. It is a preset machine that lets you overwrite a few slots with your own ideas. Still, it was the first Roland drum machine to store and play back custom patterns.

34 Preset Rhythms Across a Wide Selection

The preset list is a snapshot of what working musicians needed in 1978: four rock variations, two disco patterns, waltz, shuffle, slow rock, swing, fox trot, tango, boogie, and enka. That last one shows Roland was building for a global market, not just an American one. The presets are the backbone of the instrument, and most owners in period use probably never touched the programmable slots. They are also the reason the CR-78 turns up on records where nobody was thinking about drum machines as a compositional tool.

Fourteen Instrument Voices and an Exchangeable Tom Set

The programmer section is described as offering eight individually programmable sounds, including rhythmic elements like clavinet, congas, and shaker alongside the percussion options. The exact voice-by-voice roster is not fully documented in the archive's sources, so treat the 14-voice figure as the reliable number and the individual names as partial.

Separate Outputs and Three Trigger Outs

The rear panel carries separate outputs and three trigger outs. The CR-78 could send a trigger pulse to synthesizers in the studio, and that capability is tied directly to one of the most recognizable keyboard motifs in late-'70s pop, the stuttering line at the center of Blondie's "Heart of Glass." The sync is specific: it allows trigger signals at 48 counts per measure, which works out to 12 pulses per quarter note. That is a proprietary feel, not a general-purpose clock, and anyone trying to sync a CR-78 to modern gear will need to deal with it.

WS-1 Programmer and Step Writing

Step programming was done with the WS-1 box, which was an optional extra and not included. The survival-guide material is clear that writing patterns in with the step selector means entering each rhythm twice, because the memory holds only two measures. Collectors chase the WS-1 separately. A CR-78 without one plays presets fine but is not easy to program. Standard accessories shipped with a 2.5m connection cord and a TS-1. The Pedal Switch DP-2 and Write Switch WS-1 were options.

Historical Context

The CR-78 followed in the lineage of rhythm machines developed by Ace Tone, where Roland founder Ikutaro Kakehashi had previously worked, and it was the first Roland drum machine to use a microprocessor. At first glance it looked like the preset organ rhythm units that preceded it, the CR-68 being the closest comparison. The microprocessor gave it a level of flexibility and control those machines never had. Period coverage of the CompuRhythm line noted that Roland announced updated models to replace the popular CR-68 and CR-78, confirming the CR-78's standing as one of the most popular drum machine lines of its day (Modern Recording, September 1982, p.26).

Phil Collins used the CR-78 on "In the Air Tonight," and its austere, mechanical pulse is inseparable from that track's reputation. Blondie's "Heart of Glass" used its trigger output to drive synths, producing a keyboard figure that became one of the defining sounds of the era. The machine has never had the profile of Roland's later drum machines, though. The TR-808 and TR-606 cast much longer shadows, and period coverage reflects that ambivalence. The CR-78 has always had its fans rather than a mass following.

Collectibility & Value

The CR-78 is described as an iconic and legendary drum machine, and units come up for sale in full working order after servicing. One serviced example cited in the wild noted a new battery among the work done and a 220V configuration. Once relatively affordable, its market value has increased significantly, with recent listings showing prices starting around $2,200. That asking-price figure sits uneasily beside the completed-sales data: an August 2026 snapshot of eBay sold listings puts the high at $2,086, the median at $970, the latest at $700, with a low of $6 and a downward trend at roughly two sales a month. The gap between "$2,200 asking" and "$970 median sold" is the usual one, optimistic listings versus what buyers actually pay. Anyone shopping should weight the sold data.

Parts and accessories trade separately and cheaply relative to the machine. A Compusync 78 MIDI synchronizer for the CR-78 was listed at $305, and a factory firmware EPROM rescue ROM at $23.17. MIDI retrofit is a real path: the CR-78 can be brought under MIDI control via the Tubbutec uniPulse, and the Kenton Pro-KADI Mk2 lists the CR-78 among compatible machines. The Behringer RD-78 is a modern recreation, and its low price has no bearing on what an original costs. Common failure specifics are not well documented beyond battery replacement during servicing. The 8048 replacement warning still applies, since only the C-015 variant carries the correct resident program.