Page 171 - Robots Androids and Animatrons : 12 Incredible Projects You Can Build

7.2 Keypad wiring to speech-recognition circuit
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7.3 Top view of parts placement on PCB

(see Fig. 7.5) that brings a line high when the digits 5, 6, or 7 appear
in the most significant byte (MSB). This line becomes an enable-
disable line. This circuit brings the line high when the digits 5, 6, or
7 are displayed, so an interface should interpret this line going high
as a disable.
Team LRN
Chapter seven