Multiplex chime generator

In an electronic musical instrument having a keyboard with playing keys, a multiplexer for scanning the playing keys to produce a cyclically recurring serial data stream having time slots corresponding to the respective keys of the keyboard and a keydown pulse in a time slot corresponding to an actuated key of the keyboard, a demultiplexer connected to receive the serial data stream, and tone generating and keying circuitry controlled by said multiplexer for producing tones associated with the keys corresponding to time slots in which keydown pulses appear, the improvement being the method of multiple pitch generation comprising the steps of:

• inserting in the serial data stream pulses in predetermined time slots subsequent to the time slot in which the keydown pulse corresponding to the actuated key appears,
• shifting all of the pulses to new time slots subsequent to the respective original time slots in which they appeared wherein the relative spacing between the individual pulses remains unchanged,
• inserting a further pulse in a time slot ahead of the new time slots, and
• subsequently shifting all of the pulses ahead in the data stream so that all of the pulses except said further pulse appear in their original time slots and such that the relative spacing between the individual pulses remains unchanged.

In an electronic musical instrument having a keyboard with playing keys, a multiplexer for scanning the playing keys to produce a cyclically recurring serial data stream having time slots corresponding to the respective keys of the keyboard and a keydown pulse in a time slot corresponding to an actuated key of the keyboard, a demultiplexer connected to receive the serial data stream, and tone generating and keying circuitry controlled by said demultiplexer for producing tones associated with the keys corresponding to time slots in which keydown pulses appear, the improvement being the method of multiple pitch generation comprising the steps of:

• generating a second serial data stream synchronized with the first-mentioned serial data stream and comprising pulses in predetermined time slots subsequent to the time slot in which the keydown pulse corresponding to the actuated key appears,
• shifting all of the pulses in said second serial data stream to new time slots subsequent to the respective original time slots in which they appeared wherein the relative spacing between the individual pulses remains unchanged,
• inserting a further pulse in a time slot in said second data stream ahead of the new time slots, and
• subsequently shifting all the pulses in said second data stream ahead in the data stream so that all of the pulses except said further pulse appear in their original time slots and such that the relative spacing between the individual pulses remains unchanged.

In an electronic musical instrument including a keyboard having playing keys, the improvement being a chime generator comprising:

• multiplex means for scanning said keyboard and producing a cyclically recurring serial data stream having time slots corresponding to respective keys of the keyboard and a keydown signal in a time slot corresponding to an actuated key of the keyboard,
• an input terminal connected to receive said serial data stream,
• means connected to said input terminal for inserting in said serial data stream keydown signals in the fifth, twelfth and twentieth time slots subsequent to said time slot corresponding to an actuated key so as to form a partial chime serial data stream synchronized with said multiplex means,
• means connected to receive said partial chime data stream for delaying said partial chime data stream by five time slots,
• means connected to said means for delaying for combining said first mentioned data stream with the delayed said chime data stream to produce a composite chime data stream,
• demultiplex means synchronized with said multiplex means and having a data input connected to said means for combining for demultiplexing said composite chime data stream, and
• means associated with said demultiplex means for advancing the keydown signals ahead in said composite chime data stream by five time slots.

In an electronic musical instrument including a keyboard having playing keys, multiplex means for scanning said keys and producing a cyclically recurring serial data stream having time slots corresponding to respective keys of the keyboard and a keydown signal in a time slot corresponding to an actuated key of the keyboard, demultiplex means synchronized with said multiplex means and connected to receive said serial data stream for demultiplexing said serial data stream, the improvement being a pitch generator connected between said multiplex and demultiplex means comprising:

• means responsive to said serial data stream for inserting keydown signals in a plurality of selected time slots subsequent to said time slot corresponding to an actuated key so as to form a multiple pitch serial data stream,
• means connected to receive said multiple pitch serial data stream for shifting said keydown signals therein by a given interval of time slots to respective new time slots in said multiple pitch data stream subsequent to the original time slots thereof and wherein the time slot spacing between said keydown signals remains unchanged,
• means responsive to said multiple pitch data stream for inserting a further keydown signal in a time slot in said multiple pitch data stream earlier than said new time slots, said means for inserting having an output at which said multiple pitch serial data stream including said further keydown signal appears, and
• means connected between said last mentioned means for inserting and said demultiplex means for shifting said keydown signals ahead in said serial data stream by said given interval so that all of the keydown signals appear in time slots in said multiple pitch data stream earlier than at the output of said means for inserting.

In an electronic musical instrument including a keyboard having playing keys, the improvement being a pitch generator comprising:

• multiplex means for scanning said keyboard and producing a cyclically recurring signal data stream having time slots corresponding to respective keys of the keyboard and a keydown signal in a time slot corresponding to an actuated key of the keyboard,
• an input terminal connected to receive said data stream,
• means connected to said input terminal for inserting in said serial data stream one or more keydown signals in respective selected time slots subsequent to said time slot corresponding to an actuated key so as to form a multiple-pitch serial data stream synchronized with said multiplex means,
• means connected to receive said multiple pitch data stream for delaying said multiple pitch data stream by a given interval,
• means connected to said means for delaying for combining said first mentioned data stream with the delayed said multiple pitch data stream to produce a composite serial data stream,
• demultiplex means synchronized with said multiplex means and having a data input connected to said means for combining for demultiplexing said composite data stream, and
• means associated with said demultiplex means for advancing the keydown signals ahead in said composite data stream by said given interval prior to demultiplexing thereof.