GB1469838A - Musical instrument rhythm programmer having provision for auto matic pattern variation - Google Patents

Abstract

1469838 Automatic rhythm programmer HAMMOND CORP 9 April 1974 [20 April 1973] 15696/74 Heading G5J An automatic rhythm programmer comprises a semi-conductor read-only memory 18 containing a separate set of signal tracks for each of a number of basic rhythm patterns, the required rhythm being selected by the appropriate pattern switch 27 and the tracks being energized in a predetermined sequence by pulses from the address decoder 13, each track activating certain of the voice generators 19, subject to override by signals from the track variation decoder 31, which enables a number of preprogrammed pattern variations to be introduced. The preferred embodiment incorporates sixteen basic rhythm patterns together with four pattern variations some or all of which are automatically introduced in a predetermined sequence on closing switch 36, the rate at which variations are introduced being controllable by the setting of switch 34. The beat or beats into which any particular variation is introduced depends, in general, on the part of the beat cycle in which switch 36 is closed. The operator can alternatively introduce any of the pattern variations manually by operation of pushbutton variation switches 41. The device is controlled by a regular sequence of square wave pulses from a master oscillator 10 whose tempo can be varied by a variable resistor (58, Fig. 4, not shown), the oscillator supplying pulses to the counter 11. The counter 11 in turn supplies pulses to the address decoder 13, and also to the track variation decoder 31 both directly and via the measure select switch 34, on-off switch 36 and variation counter 38, further details of these units being given in Fig. 4 (not shown). The read-only memory 18, address decoder 13 and track decoder 31 and their interconnections are preferably incorporated into a single integrated chip 14, using MOSFET transistors. Further details of a preferred circuit for the set of tracks corresponding to the dixieland rhythm and the resulting rhythmic patterns for the four proposed pattern variations are given in Figs. 3 and 5 (not shown). The voice generators 19 produce untuned percussion sounds and chords.