SCANNING_KEYBOARD_ENCODER

Published:2009/7/10 22:30:00 Author:May | From:SeekIC

Uses RCA CA3600 IC for sampling 90 keys and providing parallel ASCII output with parity. Network on pins 1-3 sets clock at 50 kHz. Capacitor on pin 31 sets debouncetime at about 8 ms. Uppercase only or both uppercase and lowercase can be selected by switching between pins 7 and 9.Provides two-key rollover; N-key rollover can be obtained by adding diodes to keys. Each output will drive one TTL load.-D. Lancaster, TV Typewriter Cookbook, Howard W. Sams, Indianapolis, IN, 1976, p 38.



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