Roland CR-1000
A six-battery rhythm machine that runs six hours on a set of cells and hides a full diagnostic routine behind two buttons.
Overview
The CR-1000 is a rhythm machine from Roland, dated September 1986 in the service documentation. It runs on 9V DC - either six SUM3 batteries or a BOSS PSA-series AC adaptor - and draws 100mA, which the manual rates at roughly six hours of battery life. It weighs 950 grams with batteries installed and measures 304mm wide, 176mm deep, and 60mm tall. The output stage is spec'd at a maximum level of 3.5Vpp into 100K ohms, with a noise level of -74.5dBm.
The interesting part is under the plastic. The service notes describe a multiplexed sound reproduction system. A single sound ROM is addressed in sequence by a multiplex address counter built around a gate array (MBH63H114) containing eight 13-bit counters, which can generate eight different addresses concurrently. The multiplexed sounds are fetched from the ROM, converted to analog voltages, and sampled into the sample-and-hold capacitor of each individual channel. Roland's service documentation points readers to the TR-505 service notes for a fuller explanation of the circuit, noting that the two machines are "very similar to each other in circuit configuration." That's handy for repairs, since the CR-1000's voicing board follows the same architecture as the TR-505.
The sound set is where the two machines differ. The CR-1000's ROM selector table lists sixteen voices: open hi-hat, closed hi-hat, crash cymbal, ride cymbal, timbal, low tom, hi tom, mid tom, bass drum, low conga, hi conga, snare drum, low cowbell, claves, hand clap, and rim shot. The manual is explicit that only one sound differs from the TR-505, which carries a "HI COWBELL" in place of the CR-1000's claves. The voice ROM sizes vary a lot. The crash cymbal gets 32K, the ride cymbal 16K, and most everything else 8K or 4K. The bass drum, congas, snare, cowbell, claves, hand clap, and rim shot all sit at 4K.
One constraint to know about: the drum voices sharing a channel cannot sound simultaneously. The manual spells this out in both English and Japanese. Low tom, mid tom, and hi tom share one channel. Closed and open hi-hat share another, crash and ride cymbal a third, rim shot and hand clap a fourth, low and hi conga a fifth, and cowbell and claves a sixth. In the MIDI sound module mode, the note assignment is fixed and other note numbers are ignored. So a tom fill and a hi-hat pattern can layer, but two toms can't play at once.
MIDI implementation on the CR-1000 is basic. In normal and MIDI sync modes, the unit recognizes note numbers 0-127 with true voice 0-54, and 35-76 in the alternate mode. Note-on velocity is recognized from 1-127; note-off is not. Aftertouch is not recognized on either key or channel. Pitch bender is not recognized. The default basic channel is 1 in mode I and 10 in mode II, with OMNI ON/OFF behavior documented for both. Two functions get special treatment in the MIDI spec: the KEY START function and the NUANCE function. The manual notes that if power is applied while the INTRO/FILL IN/ENDING PATTERN SELECT KEY 'B' is held down, note velocity will affect the "nuance" of the rhythm. Conversely, a specific message is ignored if power is applied while KEY 'A' is held. Neither behavior shows up anywhere but the service notes.
The CR-1000 also has a built-in test program. Hold BEGUINE (rhythm key 7) and MEMORY MODE together while switching the power on, and the unit enters test mode. From there, START/STOP increments the test number and FILL IN decrements it. Nine tests are available: LED lighting, switch reading, potentiometer checking, tempo display, RAM write/read verification, MIDI IN hardware check, jack operation for START/STOP/FILL IN/RESTART, DAC output verification via oscilloscope at the cathode of D9 on the voicing board, and a sound check. Test 5 erases all user data in RAM, though the manual notes that factory data can be restored via memory initialization. Test 6 requires applying a squarewave (5Vpp, 2KHz-20KHz) to the MIDI IN jack. It's a hardware test, not a MIDI signal test, as the manual clarifies.
The tempo range is documented as more than 240 at maximum and less than 40 at minimum. Setting the tempo knob to EXT CLK displays "Ec" on the seven-segment LEDs. The unit ships with a connection cord (LP-25), and options include the BOSS PSA-100/120/220/240 AC adaptor and a DP-2 pedal switch.
The CR-1000 is not a TR-808 or TR-909. It's a compact, battery-powered rhythm machine with a sound set that overlaps heavily with the TR-505 and a channel-sharing architecture that limits layering. Its service manual reads like it was written for people who intend to open the case. The claves-instead-of-hi-cowbell difference is one for completists. With the manual, you can verify almost every subsystem using the built-in test mode without a scope, except the DAC output test, which does require one. Battery life is six hours on SUM3 cells, and it weighs 950 grams.
The service notes reference the TR-707/727, DDR-30, and TR-505 as predecessors that used the same multiplex address counter approach. That places the CR-1000 in a line of Roland machines built around this gate array technology. The MBH63H114 chip and its eight concurrent 13-bit counters were clearly a workhorse component for Roland in the mid-1980s, and the CR-1000 is a late application of that architecture in a compact, battery-powered form factor.
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