The CR-78 uses
analog drum voices that sound very little like real percussion instruments. The unit also incorporates an
NEC UPD8048C-015
microcontroller (a clone of the
Intel 8048) 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; when the CR-78 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. 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. A large cabinet version, the CompuRhythm CR-800, with capabilities between the CR-68 and CR-78, was also produced. At the same time Roland also sold the TR-66, a smaller unit that offered fewer preset rhythms and no programmability. == Sounds and rhythms ==