Dynamic one finger chording system

TLDR: In this paper, a dynamic one finger chording system with memory is connected in parallel relationship to the d.c. level voltage signal corresponding to a manually depressed key is detected, and an identification of the detected line is used as the address to a read only memory.

Abstract: A dynamic one finger chording system with memory is connected in parallel relationship to the d.c. keying lines connecting a select number of keys of the manual to a standard keyer circuit of an electronic organ. The one finger chording system scans each keying line until a line with a d.c. level voltage signal corresponding to a manually depressed key is detected. An identification of the detected line is used as the address to a read only memory. In response to the address, the read only memory provides a preselected d.c. level output signal which through appropriate output circuits drives respective keying lines. Thus one keying line has a d.c. level signal due to the manual depression of a key and a predetermined number of keying lines have a d.c. level signal due to the output signal from the one finger chording read only memory. The same keyer circuit that is used during normal playing now provides a chord output signal. When the key is released by the instrument player, the one finger chording system begins to scan the keying lines for the next key depressed. If a new key is depressed without releasing the previously depressed key, the one finger chording system removes itself from the respective keying line of the previously depressed key before beginning the scan for the new keying line with a d.c. level signal. Furthermore, upon depression of a key the system receives a load pulse of finite duration which momentarily disables the scanning and clears the one finger read only memory output so that when the scanning is resumed for the new d.c. level signal it is not confused by the previous d.c. level signal output from the read only memory. The one finger chording system has a memory mode actuatable by the instrument player and which electrically sustains the selected one finger chord after the instrument player releases the depressed key and until a new key is depressed or the memory feature deactivated.