The figure shows how to use an 8080 in a digital to analog converter. The circuit is from a Radio Electronics from February 1978. The other components are from that time, except for the TTL.
This circuit detects the presence of a pilot flame in heating systems by the presence of infrared...
In the figure we have a circuit that uses unusual components, being indicated for low frequency...
Found in older Signetics documentation, this circuit generates signals from 30 Hz to 25 kHz....